A method and device for detecting heat resistance of polyurethane material

Abstract

The present invention discloses a method and device for detecting heat resistance of polyurethane materials, including pre-embedding a temperature-responsive metal wire in the polyurethane material, causing the metal wire to undergo phase change through current stimulation to form an inner and outer double-layer spiral channel structure; collecting temperature-strain correlation data on the surface of the detection sample and internal sound wave propagation attenuation characteristic data; establishing a temperature field distribution map based on the temperature-strain correlation data, and determining the material phase separation area in combination with the sound wave attenuation data; implementing a counter-thermal scan through an adjustable-focus laser beam to record transient temperature response data; analyzing the time constant difference of the temperature response based on the microscopic thermal field distribution characteristic data and the transient temperature response data, and determining the heat conduction characteristics caused by the microscopic phase separation of the hard segment and the soft segment. The technical solution of the present invention realizes the accurate characterization of the local heat conduction characteristics of the material through the synergistic effect of the inner and outer double-layer spiral channel structure and the dual heat sources, and effectively solves the problem that the traditional method cannot distinguish the temperature non-uniformity caused by the microphase separation.

Description

Technical Field

[0001] The present invention relates to the technical field of polyurethane material detection, and in particular to a method and device for detecting the heat resistance of a polyurethane material. Background Art

[0002] Polyurethane material is a high molecular polymer generated by the reaction of isocyanate and polyol. Its molecular structure is usually composed of two types of functional units: one is the hard segment generated by the reaction of diisocyanate and short-chain diol or diamine, which has high polarity, high glass transition temperature and partial crystallinity; the other is the soft segment mainly composed of long-chain polyether or polyester polyol, which has good molecular chain flexibility, low polarity and obvious amorphous characteristics. Due to this unique molecular structure design, polyurethane materials have been widely used in building insulation, automotive parts, industrial sealing and other fields. However, in actual application, polyurethane materials often need to serve for a long time in a high temperature environment, which requires accurate evaluation of their heat resistance to ensure the safety and durability of the product.

[0003] At present, the evaluation of the heat resistance of polyurethane materials mainly adopts traditional detection methods such as thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). However, these methods have a fundamental technical problem: due to the significant differences between the hard segment and the soft segment of polyurethane materials in terms of polarity, chain flexibility and hydrogen bonding, it is difficult to form a uniform miscibility from a thermodynamic point of view. Therefore, microphase structures with different physical properties will spontaneously form during the curing and use of the material. This microphase separation phenomenon causes the material to have different local heat conduction efficiencies during the heating process, resulting in obvious temperature gradients in local areas, and may cause the hard segment and the soft segment to undergo thermal decomposition or structural reorganization under different temperature conditions. However, traditional detection methods focus on measuring the thermal response of the overall sample and cannot effectively distinguish the local temperature unevenness caused by phase separation at the microscale. This leads to systematic errors in the evaluation of the heat resistance of polyurethane materials and makes it difficult to accurately predict the performance of the material in the actual service environment. Summary of the invention

[0004] The main purpose of the present invention is to solve the technical problem that in the existing polyurethane material heat resistance detection method, traditional detection means cannot effectively distinguish the local temperature non-uniformity caused by material microphase separation, resulting in systematic errors in the evaluation of heat resistance performance.

[0005] A first aspect of the present invention provides a method for detecting the heat resistance of a polyurethane material, the method comprising:

[0006] A temperature-responsive metal wire is embedded in a polyurethane material, and an electric current is applied to the metal wire to cause a phase change of the metal wire, thereby driving the polyurethane material to form an inner and outer double-layer spiral channel structure to obtain a test sample;

[0007] Collecting temperature-strain correlation data on the surface of the test sample, and acquiring sound wave propagation attenuation characteristic data inside the test sample;

[0008] An initial temperature field distribution diagram is established based on the temperature-strain correlation data, a mesh optimization process is performed on the area where the temperature change rate exceeds a set threshold, and a material phase separation area is determined in combination with the acoustic wave propagation attenuation characteristic data to generate microscopic thermal field distribution characteristic data;

[0009] Performing counter-directional thermal scanning on the test sample by using a focusable laser beam, including an inward scanning process from the outer surface to the center of the sample and an outward scanning process from the center of the sample to the outer surface, and recording transient temperature response data in the two scanning processes;

[0010] Based on the microscopic thermal field distribution characteristic data and the transient temperature response data, the difference in time constants of temperature responses in two scanning directions is analyzed to determine the heat conduction characteristics caused by the microscopic phase separation of hard segments and soft segments inside the test sample.

[0011] Optionally, pre-embedding a temperature-responsive metal wire in the polyurethane material, applying current stimulation to the metal wire to cause the metal wire to undergo a phase change, and driving the polyurethane material to form an inner and outer double-layer spiral channel structure to obtain a test sample, comprising:

[0012] Performing temperature-controlled annealing treatment on the polyurethane material to eliminate residual stress in the polyurethane material and obtain a polyurethane matrix with uniform internal stress field distribution;

[0013] Determining the spatial distribution structure of the temperature-responsive metal wire, the temperature-responsive metal wire comprises an outer spiral metal wire located in the peripheral area of ​​the polyurethane matrix and an inner spiral metal wire located in the inner area of ​​the polyurethane matrix, and the spacing ratio between the outer spiral metal wire and the inner spiral metal wire is determined according to the phase separation area distribution of the polyurethane matrix;

[0014] Pre-embedded channels are fabricated in the polyurethane matrix according to the spatial distribution structure, and the temperature-responsive metal wires are embedded in the pre-embedded channels so that the spatial distribution of the temperature-responsive metal wires corresponds to the heat conduction path of the polyurethane matrix;

[0015] Applying increasing current to the temperature-responsive metal wire in order from outside to inside, so that the temperature-responsive metal wire undergoes a martensitic phase transformation in sequence, and an inner and outer double-layer spiral channel structure with a cross-sectional area decreasing from outside to inside is formed in the polyurethane matrix;

[0016] The inner and outer double-layer spiral channel structure is subjected to a constant temperature and pressure treatment so that the inner and outer double-layer spiral channel structure forms a stable configuration in the polyurethane matrix to obtain a test sample.

[0017] Optionally, the spatial distribution structure of the temperature-responsive metal wire is determined, wherein the temperature-responsive metal wire comprises an outer spiral metal wire located in the peripheral area of ​​the polyurethane matrix and an inner spiral metal wire located in the inner area of ​​the polyurethane matrix, and the spacing ratio between the outer spiral metal wire and the inner spiral metal wire is determined according to the phase separation region distribution of the polyurethane matrix, including:

[0018] Obtaining distribution density data of hard segments and soft segments in the polyurethane matrix;

[0019] Divide the polyurethane matrix into regions according to the distribution density data to determine the spatial distribution diagrams of hard segment-rich regions and soft segment-rich regions;

[0020] Calculating the volume ratio of the hard segment-rich region to the soft segment-rich region based on the spatial distribution diagram to obtain a phase separation degree parameter;

[0021] Setting a spacing ratio between the outer spiral metal wire and the inner spiral metal wire according to the phase separation degree parameter, wherein the spacing ratio increases as the phase separation degree parameter increases;

[0022] The outer layer spiral metal wires and the inner layer spiral metal wires are arranged according to the spacing ratio to obtain a spatial distribution structure.

[0023] Optionally, collecting the temperature-strain correlation data on the surface of the test sample and obtaining the acoustic wave propagation attenuation characteristic data inside the test sample includes:

[0024] Preheating the test sample so that the surface temperature of the test sample reaches a preset initial temperature to obtain a thermal equilibrium state test sample;

[0025] Acquiring temperature data points along the spiral channel direction of the thermal equilibrium state detection sample according to an equidistant distribution, and recording radial strain data at each data point and performing normalization processing to generate temperature-strain correlation data;

[0026] Transmitting an ultrasonic signal to the thermal equilibrium state detection sample, and collecting attenuation data of the ultrasonic signal during the propagation process in the detection sample;

[0027] The sound wave attenuation coefficients of different propagation paths are calculated according to the attenuation data to obtain the sound wave propagation attenuation characteristic data.

[0028] Optionally, the initial temperature field distribution map is established based on the temperature-strain correlation data, a grid optimization process is performed on the area where the temperature change rate exceeds a set threshold, the material phase separation area is determined in combination with the sound wave propagation attenuation characteristic data, and microscopic thermal field distribution characteristic data is generated, including:

[0029] According to the temperature-strain correlation data, a temperature field scanning path is established along the radial and circumferential directions of the inner and outer double-layer spiral channel structures, and a radial temperature distribution diagram is constructed with the intersection of the inner and outer double-layer spiral channel structures as a reference point to obtain an initial temperature field distribution diagram;

[0030] Determine a temperature mutation region in the initial temperature field distribution map, compare the temperature change rate of the temperature mutation region with the phase transition temperature threshold of the polyurethane material, divide the key monitoring region, and perform grid refinement processing on the key monitoring region;

[0031] Using the acoustic wave propagation attenuation characteristic data, acoustic analysis is performed on the key monitoring area, and according to the difference in attenuation characteristics of the hard segment and the soft segment in acoustic propagation, the spatial distribution characteristics of the phase separation area are determined;

[0032] The spatial distribution characteristics of the phase separation region are fused with the grid refinement processing result to establish microscopic thermal field distribution characteristic data reflecting the local heat conduction heterogeneity.

[0033] Optionally, determining a temperature mutation region in the initial temperature field distribution map, comparing the temperature change rate of the temperature mutation region with the phase transition temperature threshold of the polyurethane material, dividing a key monitoring region, and performing grid refinement processing on the key monitoring region includes:

[0034] Performing temperature gradient analysis on the initial temperature field distribution diagram in the radial and circumferential directions of the inner and outer double-layer spiral channel structures, marking points where the temperature gradient exceeds a first preset threshold as temperature mutation points;

[0035] Comparing the spatial distribution of the temperature mutation points with the positions of the inner and outer double-layer spiral channel structures to determine the temperature mutation area;

[0036] Calculating the instantaneous temperature change rate in the temperature mutation region, comparing the instantaneous temperature change rate with the phase transition temperature threshold of the hard segment and the soft segment of the polyurethane material, and obtaining the phase transition sensitive region;

[0037] Adaptively grid the phase change sensitive area and set the phase change sensitive area as the key monitoring area.

[0038] Optionally, the detection sample is subjected to counter-thermal scanning by a focusable laser beam, including an inward scanning process from the outer surface to the center of the sample and an outward scanning process from the center of the sample to the outer surface, and transient temperature response data in the two scanning processes are recorded, including:

[0039] The focal position and power density of the adjustable focus laser beam are adjusted, and the partition is performed according to the pre-embedded position of the temperature-responsive metal wire in the inner and outer double-layer spiral channel structure to generate a sequence of opposite scanning paths;

[0040] Performing an inward scan according to the opposite scanning path sequence, applying a first current sequence increasing from outside to inside to the temperature-responsive metal wire pre-buried in the inner and outer double-layer spiral channel structure, recording the composite thermal field temperature distribution during the inward scan, and obtaining inward temperature response data;

[0041] Performing an outward scan according to the opposing scanning path sequence, applying a second current sequence increasing from inside to outside to the temperature-responsive metal wire pre-buried in the inner and outer double-layer spiral channel structure, recording the composite thermal field temperature distribution during the outward scan, and obtaining outward temperature response data;

[0042] The inward temperature response data and the outward temperature response data are time-series aligned and compared to each other to determine the temperature response difference in the inner and outer double-layer spiral channel structure, thereby obtaining transient temperature response data.

[0043] Optionally, the inward scanning is performed according to the opposite scanning path sequence, and a first current sequence increasing from outside to inside is applied to the temperature-responsive metal wire pre-buried in the inner and outer double-layer spiral channel structure, and the composite thermal field temperature distribution during the inward scanning process is recorded to obtain the inward temperature response data, including:

[0044] Dividing the opposing scanning path sequence into a plurality of continuous spiral detection units, and determining a starting position and an ending position of each of the spiral detection units;

[0045] Applying a first current sequence to the temperature-responsive metal wire, so that the metal wire in each of the spiral detection units reaches a phase transition temperature in sequence from outside to inside, forming a radially progressive first thermal field;

[0046] Aligning the focus of the adjustable focus laser beam to each of the spiral detection units in sequence, and moving from outside to inside according to the opposite scanning path sequence to form a radially focused second thermal field;

[0047] The composite temperature distribution of the first thermal field and the second thermal field is collected along the axial direction and the circumferential direction of the inner and outer double-layer spiral channel structure to obtain inward temperature response data.

[0048] Optionally, the method of analyzing the time constant difference of the temperature response in two scanning directions based on the microscopic thermal field distribution characteristic data and the transient temperature response data to determine the heat conduction characteristics caused by the microscopic phase separation of the hard segment and the soft segment inside the test sample includes:

[0049] Performing temperature gradient calculation on the microscopic thermal field distribution characteristic data, determining a temperature gradient threshold according to the partition characteristics of the inner and outer double-layer spiral channel structure, marking an area exceeding the temperature gradient threshold as a heat conduction abnormality area, and spatially registering the heat conduction abnormality area with a collection point of the transient temperature response data;

[0050] Calculating the temperature response characteristic parameters of the abnormal heat conduction region during the inward scanning and outward scanning processes, including the temperature rise time and the temperature decay time, respectively, and generating a time constant distribution diagram reflecting the local thermal response characteristics of the material;

[0051] Determine the temperature response rate distribution characteristics in the inner and outer double-layer spiral channel structure according to the time constant distribution diagram, classify different regions in combination with the phase change characteristics of the polyurethane material, and divide them into hard segment-dominated regions and soft segment-dominated regions;

[0052] The temperature variation characteristics of the hard segment-dominated region and the soft segment-dominated region are analyzed to generate a thermal conductivity characteristic spectrum reflecting the degree of phase separation of the polyurethane material.

[0053] A second aspect of the present invention provides a polyurethane material heat resistance detection device, the polyurethane material heat resistance detection device comprising:

[0054] A sample preparation module is used to embed a temperature-responsive metal wire in a polyurethane material, apply current stimulation to the metal wire to cause a phase change of the metal wire, and drive the polyurethane material to form an inner and outer double-layer spiral channel structure to obtain a test sample;

[0055] A data acquisition module, used to acquire temperature-strain correlation data on the surface of the test sample and obtain sound wave propagation attenuation characteristic data inside the test sample;

[0056] A temperature field analysis module is used to establish an initial temperature field distribution diagram based on the temperature-strain correlation data, perform grid optimization processing on the area where the temperature change rate exceeds the set threshold, determine the material phase separation area in combination with the sound wave propagation attenuation characteristic data, and generate microscopic thermal field distribution characteristic data;

[0057] A thermal scanning control module, used for performing a counter-directional thermal scanning on the test sample by means of a focusable laser beam, including an inward scanning process from the outer surface to the center of the sample and an outward scanning process from the center of the sample to the outer surface, and recording transient temperature response data in the two scanning processes;

[0058] The characteristic analysis module is used to analyze the time constant difference of the temperature response in two scanning directions based on the microscopic thermal field distribution characteristic data and the transient temperature response data, and determine the heat conduction characteristics caused by the microscopic phase separation of the hard segment and the soft segment inside the test sample.

[0059] The technical solution provided by the embodiments of the present application has at least the following advantages:

[0060] By embedding a temperature-responsive metal wire in the polyurethane material and utilizing its phase change characteristics, a unique inner and outer double-layer spiral channel structure is formed. This utilizes the characteristics of the metal wire undergoing a martensitic phase transformation when powered on, allowing it to form a directional channel path in the polyurethane material. Since the spatial distribution of the spiral channel corresponds to the distribution of the hard and soft segments of the material, this lays the foundation for subsequent precise detection.

[0061] In the data collection phase, temperature-strain correlation data and sound wave propagation attenuation characteristic data are obtained simultaneously. Temperature-strain correlation data reflects the macroscopic response of the material during the heating process, while sound wave propagation attenuation characteristic data can reveal the changes in the internal microstructure of the material. This is because the hard segment and soft segment of the polyurethane material will show different acoustic impedances due to differences in their chemical structure and physical properties, resulting in characteristic attenuation of sound waves during propagation.

[0062] By conducting an in-depth analysis of the collected data, an initial temperature field distribution map was established, and areas with abnormal temperature change rates were monitored in detail. This analysis method fully considers the microphase separation characteristics of the hard and soft segments in the polyurethane material and can accurately capture local areas of abnormal heat conduction. In particular, during the grid optimization process, combined with the acoustic wave propagation attenuation characteristic data, the material phase separation area can be accurately identified, thereby obtaining the true microscopic thermal field distribution characteristics.

[0063] By implementing bidirectional scanning from outside to inside and from inside to outside with an adjustable focus laser beam, not only can the thermal response characteristics of the material in different directions be obtained, but also the distribution characteristics of the hard segment and the soft segment can be revealed through differential analysis of the time constant. This is because the hard segment and the soft segment will show different response rates during the heat conduction process due to their different molecular structures and arrangements.

[0064] Finally, by analyzing the time constant difference of temperature response in two scanning directions, this method can accurately determine the thermal conductivity characteristics caused by the microscopic phase separation of hard and soft segments inside the material. This analysis method not only overcomes the limitation of traditional detection methods that can only obtain overall thermal response, but also provides the correlation information between the microstructure of the material and the thermal conductivity performance, providing reliable technical support for the performance evaluation and quality control of polyurethane materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0066] Figure 1 A schematic diagram of an embodiment of a method for detecting heat resistance of polyurethane materials in an embodiment of the present invention;

[0067] Figure 2 Schematic diagram of an embodiment of a polyurethane material heat resistance detection device in an embodiment of the present invention.

[0068] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0069] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0070] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0071] In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, "and / or" in the full text includes three solutions. Taking A and / or B as an example, it includes technical solution A, technical solution B, and technical solution that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, which must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0072] An embodiment of the present application provides a method for detecting the heat resistance of a polyurethane material. Figure 1A flow chart of a polyurethane material heat resistance detection method provided in an embodiment of the present application. In this embodiment, the method includes:

[0073] See also Figure 1 , pre-embed a temperature-responsive metal wire in a polyurethane material, apply current stimulation to the metal wire to cause a phase change of the metal wire, drive the polyurethane material to form an inner and outer double-layer spiral channel structure, and obtain a test sample;

[0074] In one embodiment of the present invention, a temperature-responsive metal wire is embedded in a polyurethane material, and current stimulation is applied to the metal wire to cause the metal wire to undergo a phase change, thereby driving the polyurethane material to form an inner and outer double-layer spiral channel structure to obtain a test sample, including:

[0075] Performing temperature-controlled annealing treatment on the polyurethane material to eliminate residual stress in the polyurethane material and obtain a polyurethane matrix with uniform internal stress field distribution;

[0076] Determining the spatial distribution structure of the temperature-responsive metal wire, the temperature-responsive metal wire comprises an outer spiral metal wire located in the peripheral area of ​​the polyurethane matrix and an inner spiral metal wire located in the inner area of ​​the polyurethane matrix, and the spacing ratio between the outer spiral metal wire and the inner spiral metal wire is determined according to the phase separation area distribution of the polyurethane matrix;

[0077] Pre-embedded channels are fabricated in the polyurethane matrix according to the spatial distribution structure, and the temperature-responsive metal wires are embedded in the pre-embedded channels so that the spatial distribution of the temperature-responsive metal wires corresponds to the heat conduction path of the polyurethane matrix;

[0078] Applying increasing current to the temperature-responsive metal wire in order from outside to inside, so that the temperature-responsive metal wire undergoes a martensitic phase transformation in sequence, and an inner and outer double-layer spiral channel structure with a cross-sectional area decreasing from outside to inside is formed in the polyurethane matrix;

[0079] The inner and outer double-layer spiral channel structure is subjected to a constant temperature and pressure treatment so that the inner and outer double-layer spiral channel structure forms a stable configuration in the polyurethane matrix to obtain a test sample.

[0080] It should be specifically noted that when the polyurethane material is subjected to temperature-controlled annealing treatment, a program-controlled temperature annealing furnace is used to heat the material to a range of 20 to 30°C below the glass transition temperature and maintain it for 4 to 6 hours, so that the molecular chains can fully move and rearrange at an appropriate temperature, release the internal residual stress, and thus obtain a polyurethane matrix with a uniform internal stress field distribution. During the entire process, the temperature rise and fall rate is strictly controlled at 1 to 2°C / min to ensure that the material obtains sufficient stress balance in each area. For example, when the glass transition temperature is 120°C, the annealing temperature is set to 95°C. After being kept at this temperature for 5 hours, the stress detection instrument (such as a strain gauge) confirms that the internal stress distribution of the material has become uniform, which provides a stable physical basis for the subsequent embedded channel production and metal wire embedding. The use of this temperature-controlled annealing treatment method, on the one hand, prevents the polyurethane material from deforming due to local stress concentration during subsequent processing, and on the other hand, makes the thermal conduction path of the material more repeatable and comparable in subsequent testing.

[0081] When determining the spatial distribution structure of the temperature-responsive metal wire, the annealed polyurethane matrix was tested by an infrared spectrometer to obtain the distribution density data of the hard segment and the soft segment, and the distribution map of the microphase separation area inside the material was generated by image processing software. Taking a polyurethane sample with a size of 100mm×100mm×10mm as an example, the analysis results showed that the distribution ratio of the hard segment and the soft segment in the outer area of ​​the sample was significantly different from that in the inner area. Based on these quantitative data, the volume distribution parameters of the phase separation area were calculated using a pre-set mathematical model, so as to determine that the spacing ratio between the outer spiral metal wire and the inner spiral metal wire was 2:1, that is, the outer metal wire was arranged at 2 to 3mm from the sample surface, and the spiral spacing was set to 4mm, while the inner metal wire was arranged at 2 to 3mm from the center of the sample, and the spiral spacing was set to 2mm. This design fully reflects the spatial characteristics of the microphase separation phenomenon in the polyurethane matrix. By accurately matching the arrangement of the metal wire with the internal heat conduction path of the material, the subsequent temperature response data can better reflect the actual thermal conductivity characteristics of the material, rather than artificial interference.

[0082] Next, when making the embedded channel in the polyurethane matrix according to the determined spatial distribution structure, a precision CNC machining center or laser cutting equipment is used to process the embedded channel with a diameter of 0.3mm inside the material. The diameter of the channel is slightly larger than the size of the temperature-responsive metal wire (diameter 0.2mm) to ensure that the metal wire can be smoothly embedded and in close contact with the matrix, while ensuring the smoothness of the channel wall, and the feed speed is controlled at 100-200mm / min to ensure machining accuracy. Taking a polyurethane board as an example, a continuous embedded channel is cut along a pre-calculated spiral trajectory using CNC laser cutting equipment. The layout of these channels is strictly designed according to the previously calculated spatial distribution structure and the characteristics of the phase separation area, so that the embedded channel is completely corresponding to the heat conduction path in the polyurethane matrix, ensuring that after the subsequent metal wire is embedded, the heat conduction guide is accurately matched with the microphase separation of the material.

[0083] After the pre-embedded channel is made, a micro-manipulator or manual operation is used to embed the selected temperature-responsive metal wire (nickel-titanium shape memory alloy wire) into the pre-embedded channel section by section, ensuring that each metal wire is neatly arranged along the designed double-layer spiral path. Here, the temperature-responsive metal wire can quickly change its shape after being stimulated due to its unique shape memory effect, thereby forming a preset spiral channel structure in the polyurethane matrix. This pre-embedding method not only ensures good contact between the metal wire and the polyurethane material, but also enables the embedded metal wire to respond in a predetermined manner when current is subsequently applied, forming a spiral channel with an inner and outer double-layer structure.

[0084] Subsequently, increasing current was applied to the temperature-responsive metal wire embedded in the polyurethane matrix in an order from outside to inside, and a DC regulated power supply control system was used for precise current control. The initial current was set to 0.5A, and increased by 0.1A every 5 minutes until it reached 1.5A. As the current increased, the outer spiral metal wire first reached the martensitic phase transition temperature (about 55-60°C), underwent phase transition and deformation, and formed a spiral channel with a larger diameter; the inner spiral metal wire subsequently reached the phase transition temperature under the action of a slightly higher current, and its deformation amplitude was smaller, forming a spiral channel with a smaller diameter. This sequential design of gradually activating the metal wire from outside to inside mainly takes into account that the polyurethane material itself will show local temperature gradient differences when heated due to the uneven distribution of hard segments and soft segments; the outer metal wire is located at the periphery of the sample, and due to better heat dissipation conditions, it reaches the phase transition temperature faster, while the inner metal wire is located inside the matrix and is heated more slowly, thus achieving the goal of forming a larger channel in the outer layer and a smaller channel in the inner layer. The use of this inner and outer double-layer spiral channel structure can not only simulate the actual state of the heat conduction path inside the material, but also improve the resolution of temperature response through differentiated channel structure, thereby accurately capturing the local thermal conduction heterogeneity caused by microphase separation of polyurethane materials.

[0085] Finally, after completing the temperature-responsive metal wire phase change, the sample is placed in a constant temperature and pressure box for constant temperature and pressure treatment. The temperature is set to 40°C, the pressure is maintained at 0.2MPa, and the treatment time is 24 hours. During this treatment process, the temperature and pressure in the constant temperature and pressure box are precisely controlled to ensure that the sample maintains structural stability under fixed conditions. Through this treatment, the inner and outer double-layer spiral channel structure forms a stable configuration in the polyurethane matrix, further releasing the residual stress and stabilizing the internal structure of the material, thereby obtaining a test sample with a stable structure and a predetermined heat conduction channel. This constant temperature and constant pressure treatment not only ensures that the channel structure of the test sample will not change due to external interference in subsequent thermal scanning tests, but also enables the sample to maintain high repeatability and high stability during repeated testing.

[0086] The design of the inner and outer double-layer spiral channel structure is that it not only makes full use of the martensitic phase transformation characteristics of the shape memory alloy, but also realizes the construction of a differentiated channel structure from the outside to the inside through hierarchical and regional current increment control. This structure can accurately simulate the local temperature gradient caused by microphase separation of polyurethane materials. At the same time, in thermal conductivity detection, the size difference of different channels can finely distinguish the differences in thermal conductivity speed and temperature response time caused by the different distribution of hard segments and soft segments. For example, in actual tests, when laser scanning is heated, the outer channel has a better thermal conductivity, which will produce a faster temperature rise, while the inner channel has a slower temperature rise due to its smaller channel diameter, thus forming an obvious time constant difference in the transient temperature response data, which provides an important basis for the subsequent quantitative analysis of the internal thermal conductivity heterogeneity of polyurethane materials.

[0087] In one embodiment of the present invention, the spatial distribution structure of the temperature-responsive metal wire is determined, wherein the temperature-responsive metal wire comprises an outer spiral metal wire located in the peripheral area of ​​the polyurethane matrix and an inner spiral metal wire located in the inner area of ​​the polyurethane matrix, and the spacing ratio between the outer spiral metal wire and the inner spiral metal wire is determined according to the phase separation area distribution of the polyurethane matrix, including:

[0088] Obtaining distribution density data of hard segments and soft segments in the polyurethane matrix;

[0089] Divide the polyurethane matrix into regions according to the distribution density data to determine the spatial distribution diagrams of hard segment-rich regions and soft segment-rich regions;

[0090] Calculating the volume ratio of the hard segment-rich region to the soft segment-rich region based on the spatial distribution diagram to obtain a phase separation degree parameter;

[0091] Setting a spacing ratio between the outer spiral metal wire and the inner spiral metal wire according to the phase separation degree parameter, wherein the spacing ratio increases as the phase separation degree parameter increases;

[0092] The outer layer spiral metal wires and the inner layer spiral metal wires are arranged according to the spacing ratio to obtain a spatial distribution structure.

[0093] It should be specifically explained that, in the specific implementation, a high-resolution infrared spectrometer is used to detect the polyurethane matrix after temperature-controlled annealing treatment, and the distribution density data of the hard segment and soft segment in the matrix are first obtained. By detecting the infrared absorption peak of the sample at a specific wavelength, the absorption intensity is converted into concentration data, thereby constructing a matrix of hard segment and soft segment concentrations in each local area of ​​the polyurethane matrix. Taking a sample with a size of 100mm×100mm×10mm as an example, the data output by the detection instrument is processed by image processing software to form a distribution map, which clearly shows that the hard segment concentration in the peripheral area of ​​the sample is higher, while the soft segment concentration in the central area is higher.

[0094] Next, the polyurethane matrix is ​​divided into regions based on the obtained distribution density data, and the sample surface is divided into several regions through data analysis software. Based on the concentration ratio of hard segments to soft segments in each region, the hard segment-enriched region and the soft segment-enriched region are clearly distinguished. In the specific operation, by setting a certain concentration threshold, the region with a concentration exceeding the threshold is classified as a hard segment-enriched region, and the region below the threshold is classified as a soft segment-enriched region. For example, in the above sample, after data processing, it is shown that the hard segment concentration in the peripheral area reaches the set high value, while the central area is below this threshold. The generated spatial distribution map intuitively reflects the distribution of hard segments and soft segments inside the material.

[0095] Based on the obtained spatial distribution map, the volume of the hard segment-rich area and the soft segment-rich area is quantitatively calculated. Using digital integration or image processing algorithms, the concentration data in each divided area is accumulated to calculate the volume ratio of the hard segment and the soft segment in the sample, and then a numerical parameter is obtained, which quantitatively reflects the degree of microphase separation in the polyurethane matrix. Taking the actual test data as an example, if the calculated volume ratio of the hard segment-rich area to the soft segment-rich area is 1.8, this value is used as the phase separation degree parameter to ensure that the subsequent metal wire arrangement can accurately reflect the microphase separation characteristics inside the material.

[0096] According to the obtained phase separation degree parameter, the spacing ratio between the outer spiral wire and the inner spiral wire is set. This setting follows a clear principle, that is, the spacing ratio increases with the increase of the phase separation degree parameter, so that the arrangement of the wires can completely correspond to the distribution of the hard segment and the soft segment inside the material. For example, in a sample, if the detected phase separation degree parameter is 1.8, the spacing ratio between the outer and inner wires can be set to 2:1. At this time, the outer wire is arranged at 2 to 3 mm from the sample surface, and the spiral spacing is set to 4 mm; while the inner wire is arranged at 2 to 3 mm from the center of the sample, and the spiral spacing is set to 2 mm. This arrangement ensures that the outer wire mainly covers the hard segment-rich area, while the inner wire mainly corresponds to the soft segment-rich area, so that the overall wire arrangement is highly consistent with the heat conduction path and microphase separation area inside the material.

[0097] Finally, the outer spiral wire and the inner spiral wire are arranged according to a preset spacing ratio to form the final spatial distribution structure. The wire is embedded in the pre-embedded channel made in the polyurethane matrix according to the set spiral structure through a CNC machining center or a precision mechanical device to ensure that each wire is accurately positioned according to the design requirements. To illustrate with a specific example, in the above-mentioned 100mm×100mm×10mm sample, a continuous pre-embedded channel with a diameter of 0.3mm is processed inside the matrix by a CNC laser cutting device, and then the outer layer wire and the inner layer wire are sequentially embedded in the pre-embedded channel at a ratio of 2:1 according to the calculated spacing ratio, thereby obtaining an inner and outer double-layer spiral wire structure that can accurately reflect the distribution state of the hard segment and soft segment inside the polyurethane. In the subsequent temperature response test, this structure will serve as a guide for the heat conduction path, so that the thermal response data stimulated by laser scanning heating directly reflects the local heat conduction differences caused by microphase separation in the material, thereby improving the sensitivity and accuracy of the detection.

[0098] This operating process ensures a high degree of match between the metal wire arrangement and the microphase separation characteristics of the matrix through quantitative analysis, area division and volume calculation of the distribution of hard and soft segments in the polyurethane matrix, combined with a pre-set metal wire spacing ratio. This not only achieves precise guidance of the heat conduction path inside the material, but also ensures the reliability and repeatability of the data during the detection process.

[0099] Please continue reading Figure 1 , collecting temperature-strain correlation data on the surface of the test sample, and obtaining sound wave propagation attenuation characteristic data inside the test sample;

[0100] In one embodiment of the present invention, collecting the temperature-strain correlation data on the surface of the test sample and obtaining the acoustic wave propagation attenuation characteristic data inside the test sample includes:

[0101] Preheating the test sample so that the surface temperature of the test sample reaches a preset initial temperature to obtain a thermal equilibrium state test sample;

[0102] Acquiring temperature data points along the spiral channel direction of the thermal equilibrium state detection sample according to an equidistant distribution, and recording radial strain data at each data point and performing normalization processing to generate temperature-strain correlation data;

[0103] Transmitting an ultrasonic signal to the thermal equilibrium state detection sample, and collecting attenuation data of the ultrasonic signal during the propagation process in the detection sample;

[0104] The sound wave attenuation coefficients of different propagation paths are calculated according to the attenuation data to obtain the sound wave propagation attenuation characteristic data.

[0105] It should be specifically noted that, in the specific implementation, first, the test sample is preheated and a precision temperature-controlled furnace is used to uniformly heat the sample, and the surface temperature of the sample is strictly controlled to a preset initial temperature, so that the sample reaches a thermal equilibrium state. This process requires that the sample be placed in a temperature-stable heating environment, and the surface temperature is monitored in real time using a thermocouple until the entire sample reaches the set temperature and is maintained for a certain period of time to ensure a thermal equilibrium state.

[0106] Next, temperature data points are obtained at equal intervals along the spiral channel direction on the thermal equilibrium test sample, and high-precision micro-thermocouples or infrared thermal imagers are used as temperature measurement tools to ensure that temperature values ​​can be accurately recorded at certain distances on the sample surface. At the same time, radial strain data at each data point is recorded along the same path, and the micro-deformation of the sample surface is monitored by using fiber grating sensors or strain gauges. The obtained strain data is normalized and combined with the temperature data to form temperature-strain correlation data. Taking an actual test as an example, a temperature data point is collected every 2 mm along the spiral channel, and radial strain data at the corresponding position is collected at the same time. After normalization by data processing software, a series of accurate temperature and strain values ​​are obtained. These data form the basis for describing the local thermodynamic and mechanical response state of the sample, and provide detailed local feature information for subsequent heat conduction analysis.

[0107] Subsequently, an ultrasonic signal is emitted to the thermal equilibrium test sample, and the sample is scanned using an ultrasonic transmitter and receiver. The ultrasonic signal is emitted at a fixed frequency, and after passing through the interior of the sample, it is attenuated on different propagation paths, and the receiver is used to collect the attenuation data of the signal. The acquisition process is recorded in real time by a digital oscilloscope or ultrasonic detector to ensure high accuracy and high resolution of the data. Taking the detection of a certain sample as an example, the ultrasonic signal is emitted from one side of the sample, transmitted through the interior of the sample to the other side for reception, and the attenuation data of the signal amplitude on different paths is obtained during the recording process, thereby reflecting the influence of the internal structure of the sample on the propagation of sound waves. The design of this step aims to utilize the ultrasonic propagation characteristics to directly correlate the relationship between the internal microstructure changes of the material and the local thermal conductivity characteristics by measuring the attenuation coefficient, thereby providing another independent data source for analyzing the distribution characteristics of hard segments and soft segments in the polyurethane matrix.

[0108] Finally, according to the collected attenuation data, the sound wave attenuation coefficients of different propagation paths are calculated through mathematical models and digital signal processing algorithms to obtain the sound wave propagation attenuation characteristic data. Here, a common numerical calculation method is used to compare the amplitude value of the ultrasonic wave attenuation on each path with the propagation distance to obtain the attenuation coefficient of each path. This coefficient has a quantitative relationship with the internal microstructure of the sample. To illustrate with a specific example, if the ultrasonic signal of a certain path passes through a 50mm path from the transmitting end to the receiving end, the ratio of its initial amplitude to the received amplitude is logarithmically calculated to obtain an attenuation coefficient of 0.02dB / mm. This value constitutes the sound wave attenuation characteristic data after multi-path calculation, which can intuitively reflect the local sound wave propagation differences caused by microphase separation in polyurethane materials. This data is combined with the aforementioned temperature-strain correlation data to facilitate further analysis of the local thermal conductivity characteristics of the material.

[0109] The whole process uses preheating to ensure that the sample reaches thermal equilibrium. The temperature and strain data are collected uniformly along the spiral channel to build temperature-strain correlation data. The ultrasonic signal emission and its attenuation data are collected and calculated to form a multimodal data acquisition system. This design not only ensures the stability and accuracy of the test data, but also through the joint analysis of multiple physical parameters, it can more comprehensively reflect the structural characteristics caused by local heat conduction and microphase separation inside the polyurethane material, providing strong support for the subsequent accurate determination of abnormal heat conduction areas.

[0110] Please continue reading Figure 1 , establishing an initial temperature field distribution diagram based on the temperature-strain correlation data, performing grid optimization processing on the area where the temperature change rate exceeds the set threshold, determining the material phase separation area in combination with the acoustic wave propagation attenuation characteristic data, and generating microscopic thermal field distribution characteristic data;

[0111] In one embodiment of the present invention, the initial temperature field distribution diagram is established based on the temperature-strain correlation data, a grid optimization process is performed on the area where the temperature change rate exceeds the set threshold, the material phase separation area is determined in combination with the acoustic wave propagation attenuation characteristic data, and microscopic thermal field distribution characteristic data is generated, including:

[0112] According to the temperature-strain correlation data, a temperature field scanning path is established along the radial and circumferential directions of the inner and outer double-layer spiral channel structures, and a radial temperature distribution diagram is constructed with the intersection of the inner and outer double-layer spiral channel structures as a reference point to obtain an initial temperature field distribution diagram;

[0113] Determine a temperature mutation region in the initial temperature field distribution map, compare the temperature change rate of the temperature mutation region with the phase transition temperature threshold of the polyurethane material, divide the key monitoring region, and perform grid refinement processing on the key monitoring region;

[0114] Using the acoustic wave propagation attenuation characteristic data, acoustic analysis is performed on the key monitoring area, and according to the difference in attenuation characteristics of the hard segment and the soft segment in acoustic propagation, the spatial distribution characteristics of the phase separation area are determined;

[0115] The spatial distribution characteristics of the phase separation region are fused with the mesh refinement processing result to establish microscopic thermal field distribution characteristic data reflecting the local heat conduction heterogeneity.

[0116] It should be specifically noted that after preliminary processing of the temperature-strain correlation data using a high-resolution infrared thermal imager and digital mapping software, a temperature field scanning path is constructed along the radial and circumferential directions of the inner and outer double-layer spiral channel structure. The design of this scanning path is based on the geometric characteristics of the inner and outer spiral channel structure of the sample, and the intersection of the structure is used as a fixed reference coordinate to form a set of regular scanning grids on the entire sample surface. During the scanning process, each intersection and the measurement points around it record temperature data through precision sensors. The data is mainly acquired by high-precision micro-thermocouples or infrared thermal imagers, and the temperature data is stored and visualized according to spatial coordinates in combination with digital processing methods to form a preliminary temperature field distribution map. Taking a polyurethane sample with an inner and outer double-layer spiral channel structure as an example, the intersection is determined as the reference point of the coordinate system. The data collected along the radial direction reflects the trend of temperature change from the center of the sample to the periphery, while the data along the circumferential direction shows the local distribution difference of temperature at the same radial position. All data are summarized to form an initial temperature field distribution map, which intuitively shows the temperature gradient distribution on the sample surface and provides an accurate basis for subsequent analysis.

[0117] In the initial temperature field distribution diagram, the temperature gradient of each area is differentially calculated based on the digital processing results to identify the area where the temperature mutation occurs. This step uses a mathematical algorithm to calculate the temperature change rate between adjacent sampling points, and strictly compares the calculation results with the phase transition temperature threshold of the polyurethane material to divide the temperature mutation area. Taking a specific example, when the detection data shows that the temperature change rate of a certain area exceeds the known phase transition temperature threshold of the material (for example, set to 10°C / cm), the area is divided into a key monitoring area. Subsequently, an adaptive grid refinement processing algorithm is applied in these key monitoring areas to further refine the original coarse grid segmentation into smaller grid units, such as from a spacing of 5mm to a spacing of 1mm. This process is automated through numerical simulation software to ensure that the resolution of the temperature field data in high-gradient areas is greatly improved, so that the details of local heat conduction changes can be captured more accurately, and a more refined temperature distribution basis is provided for subsequent acoustic analysis.

[0118] At the same time, during the acquisition of the acoustic wave propagation attenuation characteristic data, a standard ultrasonic detection device is used to transmit an ultrasonic signal of a fixed frequency to the thermal equilibrium state detection sample, and a digital oscilloscope is used to record the transmission attenuation of the ultrasonic wave inside the sample. After calculation by the signal processing algorithm, the attenuation coefficient data on different propagation paths are obtained. These data reflect the local density and rigidity changes caused by microphase separation inside the sample, because the attenuation characteristics of the hard segment and the soft segment during the acoustic wave propagation process are significantly different. Taking a specific case as an example, in a key monitoring area, it is calculated that the attenuation coefficient on the propagation path presents a high value, which can be inferred that the area is mainly a hard segment-enriched area; and if the attenuation coefficient is low, it indicates that the soft segment is dominant in this area. Therefore, the analysis results based on the acoustic wave data and the temperature field scanning data form two independent information reflecting the microphase separation state inside the material.

[0119] In the next data fusion stage, the temperature field distribution data after adaptive grid refinement and the acoustic wave propagation attenuation characteristic data will be spatially aligned and jointly analyzed by data processing software. All data are normalized according to the same coordinate system to ensure that the temperature change rate of each grid unit matches the corresponding acoustic wave attenuation coefficient one by one. Finally, the two data are organically fused using numerical integration or data fitting algorithms to establish a microscopic thermal field distribution characteristic data reflecting the local thermal conduction heterogeneity. For example, in a certain area, if the grid data indicates that there is a temperature mutation, and the acoustic wave data also shows a high attenuation coefficient, then after fusion, it can be clearly indicated that the area is a hard segment-enriched area, and its thermal conduction characteristics are significantly different from those of the soft segment area. The fused data is presented graphically to form a color-coded thermal field distribution map, which intuitively shows the coupling effect of local temperature gradient and acoustic characteristics. This data set provides a quantitative description of the effect of microphase separation inside the material on local thermal conduction, which can be used for further material performance evaluation and structural optimization analysis.

[0120] In one embodiment of the present invention, determining a temperature mutation region in the initial temperature field distribution map, comparing the temperature change rate of the temperature mutation region with the phase transition temperature threshold of the polyurethane material, dividing a key monitoring region, and performing grid refinement processing on the key monitoring region include:

[0121] Performing temperature gradient analysis on the initial temperature field distribution diagram in the radial and circumferential directions of the inner and outer double-layer spiral channel structures, marking points where the temperature gradient exceeds a first preset threshold as temperature mutation points;

[0122] Comparing the spatial distribution of the temperature mutation points with the positions of the inner and outer double-layer spiral channel structures to determine the temperature mutation area;

[0123] Calculating the instantaneous temperature change rate in the temperature mutation region, comparing the instantaneous temperature change rate with the phase transition temperature threshold of the hard segment and the soft segment of the polyurethane material, and obtaining the phase transition sensitive region;

[0124] Adaptively grid the phase change sensitive area and set the phase change sensitive area as the key monitoring area.

[0125] It should be specifically stated that, in the specific implementation, first, by performing temperature gradient analysis on the initial temperature field distribution map, data extraction and differential calculation are performed on the radial and circumferential directions of the inner and outer double-layer spiral channel structures, and the temperature difference between each sampling point and its adjacent point is divided by the spatial distance using the numerical differentiation method, so as to obtain the temperature gradient value at each position. This process is processed using common data processing software, and combined with the digital image processing algorithm, the continuous temperature change in the temperature field is converted into discrete gradient data, and based on the geometric characteristics of the inner and outer double-layer spiral channel structure, the points where the temperature gradient exceeds the first preset threshold are clearly marked in the temperature field scanning path. These points show significant gradient characteristics due to the rapid change in temperature and are called temperature mutation points. For example, in the radial scanning data of a certain test sample, if the temperature difference between two adjacent points is greater than the set threshold of 10°C / cm, the position is automatically marked as a temperature mutation point, thereby realizing the preliminary identification of the area of ​​abnormal temperature change.

[0126] Next, the spatial distribution of the temperature mutation points is compared with the position of the inner and outer double-layer spiral channel structures. By overlapping the coordinate information of the temperature mutation points with the geometric coordinates of the channel structure, the distribution of the temperature mutation points in the entire channel structure is clearly displayed using CNC drawing software. Through comparative analysis, it is possible to determine which areas have obvious clustering trends in the distribution of temperature mutation points and spiral channels, and then divide these clustered temperature mutation points into temperature mutation areas. Taking a specific sample as an example, when the density of temperature mutation points in a certain area along the spiral channel is much higher than that in other areas, it can be considered that there is a local temperature drastic change phenomenon in this area, and it is defined as a temperature mutation area. This step not only ensures the accurate extraction of the temperature mutation points, but also further determines the location and range of the temperature anomaly through spatial comparison with the channel structure, thereby providing an intuitive spatial reference for subsequent processing.

[0127] After determining the temperature mutation area, the temperature data in the area is further processed to calculate the instantaneous temperature change rate. Using numerical differentiation technology, the temperature change of each sampling point in the area at the moment of temperature mutation is calculated in the time dimension, that is, the change in temperature in a very short time interval is divided by the time interval to obtain the instantaneous temperature change rate. This value can directly reflect the phase change sensitivity of the material in the area by comparing it with the phase transition temperature threshold of the hard segment and the soft segment in the polyurethane material. For example, if the instantaneous temperature change rate in a temperature mutation area reaches 15℃ / s, and the phase transition temperature threshold of the hard segment or the soft segment in the known polyurethane material is 12℃ / s, then the area is identified as a phase change sensitive area. In this process, the calculation method used ensures high-resolution measurement of the temperature change rate, so that the correlation between local temperature anomalies and the phase change characteristics of the material can be accurately reflected, thereby distinguishing the phase change sensitive area from the ordinary area at the data level.

[0128] After the phase change sensitive area is identified, the area is then subjected to adaptive meshing. The adaptive meshing technology uses a software algorithm to refine the mesh in the phase change sensitive area in the initial temperature field distribution map, and divides the original coarse mesh into more and smaller mesh units to improve the acquisition accuracy of temperature and strain data in the area. This process uses an adaptive meshing algorithm to first partition the entire temperature field in a coarse mesh manner, and then automatically adjust the mesh size according to the local change rate of the temperature gradient data in the identified phase change sensitive area, so that the area with significant temperature changes obtains a higher spatial resolution. For example, in a phase change sensitive area, the original 5mm spacing grid is refined to a 1mm grid, so that more detailed temperature fluctuation information can be captured in this area. Through this adaptive meshing, the entire phase change sensitive area is defined as a key monitoring area, and the resolution and accuracy of its temperature field data in this area are significantly improved.

[0129] Please continue reading Figure 1 , performing a counter-directional thermal scan on the test sample by means of a focusable laser beam, including an inward scanning process from the outer surface to the center of the sample and an outward scanning process from the center of the sample to the outer surface, and recording transient temperature response data in the two scanning processes;

[0130] In one embodiment of the present invention, the detection sample is subjected to counter-thermal scanning by a focusable laser beam, including an inward scanning process from the outer surface to the center of the sample and an outward scanning process from the center of the sample to the outer surface, and transient temperature response data in the two scanning processes are recorded, including:

[0131] The focal position and power density of the adjustable focus laser beam are adjusted, and the partition is performed according to the pre-embedded position of the temperature-responsive metal wire in the inner and outer double-layer spiral channel structure to generate a sequence of opposite scanning paths;

[0132] Performing an inward scan according to the opposite scanning path sequence, applying a first current sequence increasing from outside to inside to the temperature-responsive metal wire pre-buried in the inner and outer double-layer spiral channel structure, recording the composite thermal field temperature distribution during the inward scan, and obtaining inward temperature response data;

[0133] Performing an outward scan according to the opposing scanning path sequence, applying a second current sequence increasing from inside to outside to the temperature-responsive metal wire pre-buried in the inner and outer double-layer spiral channel structure, recording the composite thermal field temperature distribution during the outward scan, and obtaining outward temperature response data;

[0134] The inward temperature response data and the outward temperature response data are time-series aligned and compared to each other to determine the temperature response difference in the inner and outer double-layer spiral channel structure, thereby obtaining transient temperature response data.

[0135] It should be specifically stated that, in the specific implementation, first, by adjusting the focal position and power density of the adjustable focus laser beam, ensure that the laser beam can be accurately focused on the pre-set scanning path during the entire scanning process. Using an electric focusing mechanism and a digital control system, the focal position of the laser beam is aligned with the position of the temperature-responsive metal wire embedded in the inner and outer double-layer spiral channel structure, thereby generating a set of partitions based on the channel structure. According to the position of the temperature-responsive metal wire in the polyurethane matrix, the sample is divided into a plurality of different scanning areas, each of which corresponds to a specific scanning path. The main consideration for using an adjustable focus laser beam instead of hot air blowing in this method is that the laser beam has extremely high directionality and focus stability, and its laser energy can be concentrated and transferred to a local area in a very short time, while hot air blowing will introduce airflow disturbance and diffusion effects during the heat transfer process, resulting in blurred thermal excitation areas and uneven temperature distribution.

[0136] After the sequence of opposite scanning paths is generated, the inward scanning process is started first. In this process, along the pre-defined scanning path, a DC regulated power supply is used to apply a first current sequence that increases from the outside to the inside to the temperature-responsive metal wire embedded in the inner and outer double-layer spiral channel structure. This increasing current excitation causes the metal wire in the outer layer of the sample to reach its martensitic phase transition temperature first, rapidly deform, and stimulate the local area to generate a composite thermal field. At this time, a high-precision temperature sensor (such as a micro-thermocouple or infrared thermal imager) records the temperature distribution changes caused by laser focused heating during the scanning process in real time, thereby forming a set of inward temperature response data. Taking a certain test sample as an example, when the outer metal wire first completes the phase transition under the 0.5A current excitation, its surrounding temperature rises rapidly, and the data recording system uses this temperature change as part of the inward scanning data to ensure the synchronization and accuracy of laser heating and metal wire activation.

[0137] Next, the outward scanning process is carried out according to the same sequence of opposite scanning paths, but the order of the applied current is opposite to that of the inward scanning, that is, a second current sequence that increases from the inside to the outside is adopted. In this process, the temperature rise rate of the inner metal wire is slow because it is inside a relatively closed matrix, but under the action of the gradual increase in current, the inner metal wire gradually reaches the phase change temperature and deforms, thereby stimulating the thermal field response of the corresponding area. During the recording process, a high-precision temperature sensor is also used to monitor the temperature changes on the scanning path in real time, and the data is collected to form the outward temperature response data. In this way, the outward scanning data can supplement the inward scanning data, and together form a complete thermal field distribution map, showing the dynamic changes of the temperature response from the inside to the outside or from the outside to the inside.

[0138] Subsequently, the inward temperature response data and the outward temperature response data are time-series aligned and compared by digital signal processing technology. This step uses a commonly used time synchronization algorithm to align the temperature data in the two scanning modes according to a unified time reference, ensuring that the temperature value corresponding to each moment can be accurately compared in the inward and outward scanning data. Through comparative analysis, the temperature response differences caused by the sequential activation of the temperature-responsive metal wires in the inner and outer double-layer spiral channel structure can be identified. These differences are reflected in the data in different forms of parameters such as temperature rise rate, peak temperature and decay time, thereby forming a set of detailed data records reflecting local thermal conduction heterogeneity and transient temperature response characteristics. For example, in a certain test sample, the temperature response rise time recorded by the inward scan is 2.5 seconds, while the temperature response rise time recorded by the outward scan is 3.0 seconds. After comparative analysis, this data difference forms transient temperature response data, which provides a reliable basis for the subsequent evaluation of the thermal conductivity performance of the material.

[0139] In one embodiment of the present invention, the inward scanning is performed according to the opposite scanning path sequence, and a first current sequence increasing from outside to inside is applied to the temperature-responsive metal wire pre-buried in the inner and outer double-layer spiral channel structure, and the composite thermal field temperature distribution during the inward scanning process is recorded to obtain the inward temperature response data, including:

[0140] Dividing the opposing scanning path sequence into a plurality of continuous spiral detection units, and determining a starting position and an ending position of each of the spiral detection units;

[0141] Applying a first current sequence to the temperature-responsive metal wire, so that the metal wire in each of the spiral detection units reaches a phase transition temperature in sequence from outside to inside, forming a radially progressive first thermal field;

[0142] Aligning the focus of the adjustable focus laser beam to each of the spiral detection units in sequence, and moving from outside to inside according to the opposite scanning path sequence to form a radially focused second thermal field;

[0143] The composite temperature distribution of the first thermal field and the second thermal field is collected along the axial direction and the circumferential direction of the inner and outer double-layer spiral channel structure to obtain inward temperature response data.

[0144] It should be specifically explained that, in the specific implementation, the scanning heating method of the adjustable focus laser beam is used to further subdivide the pre-generated opposite scanning path sequence into multiple continuous spiral detection units in order to achieve fine monitoring of the temperature-responsive metal wire activation process. First, the laser scanning system is used to divide the entire scanning path sequence into multiple continuous detection units based on the geometric characteristics of the inner and outer double-layer spiral channel structure, and the starting position and end position of each detection unit are clearly defined through the digital coordinate system. This process uses image processing and data segmentation algorithms, and takes each intersection and its adjacent area on the laser scanning path as the basis for segmentation, thereby forming independent and continuous spiral detection units. Taking a polyurethane test sample with embedded metal wire as an example, the scanning path of the outer spiral channel is divided into several detection units with a length of about 10 mm through the CNC system. The starting and ending positions of each detection unit are accurately defined in the CNC program to ensure the consistency and repeatability of the time and space coordinates of subsequent data acquisition.

[0145] After the spiral detection unit is divided, a DC regulated power supply is used to apply current excitation to the temperature-responsive metal wire embedded in each spiral detection unit according to a preset first current sequence. During this process, the outer metal wire first reaches its martensitic phase transition temperature in an order from the outside to the inside, and then rapidly deforms to form a radially progressive first thermal field. During the activation process, the DC current increases in fixed steps. For example, the initial current is 0.5 amperes, and it increases by 0.1 amperes at regular intervals until the outer metal wire is activated and the inner metal wire reaches the phase transition temperature in turn. This method uses current step control technology to ensure that the metal wires in each detection unit are activated in sequence according to a predetermined order, thereby forming a thermal field with a significant gradient change in each unit, which presents a spatial characteristic of decreasing from the outside to the inside. Taking a certain test sample as an example, the outer metal wire in the first test unit quickly reaches the phase change temperature of 55°C under 0.5 amperes, forming a thermal field with a larger diameter, while the inner metal wire in the same unit reaches the phase change temperature under 0.9 amperes of excitation, forming a thermal field with a smaller diameter, thus forming an obvious radial progressive thermal field structure.

[0146] Subsequently, the focus of the adjustable laser beam is aligned with each spiral detection unit in turn, and moves from the outside to the inside according to the sequence of opposite scanning paths to form a radially focused second thermal field. This process uses the high-speed galvanometer device and digital control technology of the laser system to ensure that the laser focus is accurately placed in each detection unit. The high directivity and local high power density of the laser beam allow an additional layer of local thermal field to be formed in each detection unit in addition to the first thermal field formed by the metal wire excitation. This thermal field can further heat the sample and amplify the local temperature change signal.

[0147] After the second thermal field with radial focusing is formed, the composite temperature distribution of the first thermal field and the second thermal field is collected along the axial and circumferential directions of the inner and outer double-layer spiral channel structures using high-resolution temperature sensors. The sensor records the dynamic changes of temperature in each detection unit in real time and generates inward temperature response data. These data are synchronously recorded by a digital acquisition system to ensure the timing consistency of temperature response under laser scanning and current excitation. After data acquisition, the temperature distribution information in each detection unit is spliced ​​and integrated using data processing software to obtain a complete inward temperature response data map. This map can intuitively reflect the temperature response differences of the sample caused by the sequential activation of the metal wire and laser heating in different detection units, and provide detailed dynamic data support for the analysis of local thermal conductivity characteristics and thermal conductivity heterogeneity of the material.

[0148] Please continue reading Figure 1 Based on the microscopic thermal field distribution characteristic data and the transient temperature response data, the difference in time constants of temperature response in the two scanning directions is analyzed to determine the heat conduction characteristics caused by the microscopic phase separation of hard segments and soft segments inside the test sample.

[0149] In one embodiment of the present invention, the method of analyzing the time constant difference of the temperature response in two scanning directions based on the microscopic thermal field distribution characteristic data and the transient temperature response data to determine the heat conduction characteristics caused by the microscopic phase separation of the hard segment and the soft segment inside the test sample includes:

[0150] Performing temperature gradient calculation on the microscopic thermal field distribution characteristic data, determining a temperature gradient threshold according to the partition characteristics of the inner and outer double-layer spiral channel structure, marking an area exceeding the temperature gradient threshold as a heat conduction abnormality area, and spatially registering the heat conduction abnormality area with a collection point of the transient temperature response data;

[0151] Calculating the temperature response characteristic parameters of the abnormal heat conduction region during the inward scanning and outward scanning processes, including the temperature rise time and the temperature decay time, respectively, and generating a time constant distribution diagram reflecting the local thermal response characteristics of the material;

[0152] Determine the temperature response rate distribution characteristics in the inner and outer double-layer spiral channel structure according to the time constant distribution diagram, classify different regions in combination with the phase change characteristics of the polyurethane material, and divide them into hard segment-dominated regions and soft segment-dominated regions;

[0153] The temperature variation characteristics of the hard segment-dominated region and the soft segment-dominated region are analyzed to generate a thermal conductivity characteristic spectrum reflecting the degree of phase separation of the polyurethane material.

[0154] It should be specifically explained that, in the specific implementation, first, when the temperature gradient is calculated for the microscopic thermal field distribution characteristic data, the pre-collected temperature field distribution map is numerically differentiated using high-precision data processing software, and the temperature change between each data point and its adjacent data point is divided by its corresponding spatial distance, thereby obtaining the local temperature gradient value. This step converts the continuous temperature field into a discrete temperature gradient distribution map through a digital algorithm, clearly showing the area where the local temperature changes dramatically. This method can not only quantify the overall distribution of the temperature field, but also accurately reflect the local heat conduction anomaly caused by the microphase separation inside the polyurethane material. Taking a sample with an inner and outer double-layer spiral channel structure as an example, by performing point-by-point differentiation on its temperature distribution data, it can be clearly seen in the temperature field map that the temperature gradient of some areas rises sharply. When the data value of this area exceeds the preset temperature gradient threshold, it is marked as a heat conduction abnormal area. This marking operation relies on the pre-defined partition features in the inner and outer double-layer spiral channel structure, which provides an accurate geometric boundary for data division, so that the determination of the abnormal area has a clear spatial positioning and numerical basis.

[0155] Next, the marked thermal conduction anomaly area is spatially registered with the acquisition points of the transient temperature response data to ensure that the temperature gradient anomaly area strictly corresponds to the actual thermal response data in space. Using digital map registration technology, the temperature field data and transient temperature response data are corrected according to the same coordinate system, and the acquisition points of the temperature response data in the area are matched corresponding to the center position and boundary of each abnormal area to ensure spatial consistency during the data fusion process. This step uses precise digital processing and image registration algorithms to enable the temperature response data used in subsequent analysis to directly reflect the dynamic characteristics of the previously marked thermal conduction anomaly area, thereby providing sufficient basis for the quantitative study of local thermal conduction behavior inside the material.

[0156] Subsequently, after the spatial registration is completed, the characteristic parameters of the temperature response of the abnormal heat conduction area during the inward scanning and outward scanning processes are calculated respectively. By performing time series analysis on the temperature data in each abnormal area, key parameters such as temperature rise time and temperature decay time are extracted. The digital signal processing method is used to fit the slope of the temperature response curve in the rising stage and the decay stage to obtain the transient temperature response time constant of each area. This time constant distribution diagram not only intuitively shows the difference in thermal response speed in different areas, but also provides an effective indicator for quantitatively evaluating the internal thermal conduction characteristics of the material. Taking the actual detection as an example, in a certain abnormal area, the calculated temperature rise time constant is 2.8 seconds, while in another abnormal area it is 3.2 seconds. This numerical difference can reflect the difference in thermal conduction efficiency within the area and provide a reliable numerical basis for subsequent regional classification.

[0157] Furthermore, based on the obtained time constant distribution diagram, the temperature response rate distribution characteristics in the inner and outer double-layer spiral channel structure are determined by statistical analysis methods. By comparing the rise and decay time constants of the temperature response in each detection unit, the local temperature response is classified in detail according to the inherent phase change characteristics of the material. The hard segment and soft segment in the polyurethane material show obvious differences in the rate of response to heat conduction due to different molecular chain structures and phase separation characteristics. Using the known phase transition temperature threshold, the area with a faster response rate is classified as the hard segment-dominated area, while the area with a slower response rate is classified as the soft segment-dominated area. This classification basis is not only based on the accurate calculation of the time constant, but also combined with the material phase change theory, and the specific behavior of the hard segment and the soft segment in the temperature response process is determined by comparing experimental data. Taking a set of detection data as an example, when the temperature rise time constant of a certain area during the inward scanning process is significantly lower than the average value, accompanied by a faster temperature decay rate, the area is judged to be a hard segment-dominated area; conversely, when the temperature rise and decay time constants are both long, the area is judged to be a soft segment-dominated area.

[0158] Finally, the temperature change characteristics of the hard segment-dominated area and the soft segment-dominated area are comprehensively analyzed to generate a thermal conductivity characteristic spectrum reflecting the degree of phase separation of the polyurethane material. Through the detailed analysis of the temperature response curve in each area, the temperature response parameters of each area (such as rise time, decay time, peak temperature, etc.) are fused and statistically processed to form a color-coded spectrum, which intuitively shows the differences in thermal conductivity characteristics caused by microphase separation in different areas of the material. The color and numerical distribution in the spectrum directly reflect the relative proportion of the hard segment and soft segment distribution and the degree of phase separation, thus providing a solid data basis for the quantitative evaluation of the thermal properties of the material. The entire operation process has been carefully designed. First, the abnormal heat conduction area is accurately identified through temperature gradient calculation, and then spatial registration is used to ensure data consistency. Then, the quantitative indicators of the temperature response characteristics in the area are obtained through detailed transient temperature response parameter calculation. Finally, the area is classified and the spectrum is generated in combination with the phase change characteristics. This process not only makes full use of common methods such as digital image processing, signal processing and statistical analysis, but also ensures the data accuracy and spatial matching of each step, providing a complete, repeatable and scientifically rigorous experimental plan for the analysis of local thermal conductivity heterogeneity caused by microphase separation inside polyurethane materials.

[0159] The above describes the polyurethane material heat resistance detection method in the embodiment of the present invention. The following describes the polyurethane material heat resistance detection device in the embodiment of the present invention. Figure 2 In one embodiment of the present invention, a device for detecting heat resistance of polyurethane material comprises:

[0160] The sample preparation module 101 is used to embed a temperature-responsive metal wire in a polyurethane material, apply current stimulation to the metal wire to cause the metal wire to undergo a phase change, and drive the polyurethane material to form an inner and outer double-layer spiral channel structure to obtain a test sample;

[0161] The data acquisition module 102 is used to acquire temperature-strain correlation data on the surface of the test sample and obtain sound wave propagation attenuation characteristic data inside the test sample;

[0162] The temperature field analysis module 103 is used to establish an initial temperature field distribution diagram based on the temperature-strain correlation data, perform grid optimization processing on the area where the temperature change rate exceeds the set threshold, determine the material phase separation area in combination with the sound wave propagation attenuation characteristic data, and generate microscopic thermal field distribution characteristic data;

[0163] The thermal scanning control module 104 is used to perform a counter-directional thermal scanning on the test sample by using a focusable laser beam, including an inward scanning process from the outer surface to the center of the sample and an outward scanning process from the center of the sample to the outer surface, and record transient temperature response data in the two scanning processes;

[0164] The characteristic analysis module 105 is used to analyze the time constant difference of the temperature response in two scanning directions based on the microscopic thermal field distribution characteristic data and the transient temperature response data, and determine the heat conduction characteristics caused by the microscopic phase separation of the hard segment and the soft segment inside the test sample.

[0165] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for detecting heat resistance of polyurethane materials, characterized in that: include: A temperature-responsive metal wire is embedded in a polyurethane material, and an electric current is applied to the metal wire to cause a phase change of the metal wire, thereby driving the polyurethane material to form an inner and outer double-layer spiral channel structure to obtain a test sample; Collecting temperature-strain correlation data on the surface of the test sample, and acquiring sound wave propagation attenuation characteristic data inside the test sample; An initial temperature field distribution diagram is established based on the temperature-strain correlation data, a mesh optimization process is performed on the area where the temperature change rate exceeds a set threshold, and a material phase separation area is determined in combination with the acoustic wave propagation attenuation characteristic data to generate microscopic thermal field distribution characteristic data; Performing counter-directional thermal scanning on the test sample by using a focusable laser beam, including an inward scanning process from the outer surface to the center of the sample and an outward scanning process from the center of the sample to the outer surface, and recording transient temperature response data in the two scanning processes; Based on the microscopic thermal field distribution characteristic data and the transient temperature response data, the difference in time constants of temperature responses in two scanning directions is analyzed to determine the heat conduction characteristics caused by the microscopic phase separation of hard segments and soft segments inside the test sample.

2. The polyurethane material heat resistance detection method according to claim 1, characterized in that: The method includes pre-embedding a temperature-responsive metal wire in a polyurethane material, applying an electric current to the metal wire to cause the metal wire to undergo a phase change, and driving the polyurethane material to form an inner and outer double-layer spiral channel structure to obtain a test sample, including: Performing temperature-controlled annealing treatment on the polyurethane material to eliminate residual stress in the polyurethane material and obtain a polyurethane matrix with uniform internal stress field distribution; Determining the spatial distribution structure of the temperature-responsive metal wire, the temperature-responsive metal wire comprises an outer spiral metal wire located in the peripheral area of ​​the polyurethane matrix and an inner spiral metal wire located in the inner area of ​​the polyurethane matrix, and the spacing ratio between the outer spiral metal wire and the inner spiral metal wire is determined according to the phase separation area distribution of the polyurethane matrix; Pre-embedded channels are fabricated in the polyurethane matrix according to the spatial distribution structure, and the temperature-responsive metal wires are embedded in the pre-embedded channels so that the spatial distribution of the temperature-responsive metal wires corresponds to the heat conduction path of the polyurethane matrix; Applying increasing current to the temperature-responsive metal wire in order from outside to inside, so that the temperature-responsive metal wire undergoes a martensitic phase transformation in sequence, and an inner and outer double-layer spiral channel structure with a cross-sectional area decreasing from outside to inside is formed in the polyurethane matrix; The inner and outer double-layer spiral channel structure is subjected to a constant temperature and pressure treatment so that the inner and outer double-layer spiral channel structure forms a stable configuration in the polyurethane matrix to obtain a test sample.

3. The polyurethane material heat resistance detection method according to claim 2, characterized in that: The determining of the spatial distribution structure of the temperature-responsive metal wire, wherein the temperature-responsive metal wire comprises an outer spiral metal wire located in the peripheral area of ​​the polyurethane matrix and an inner spiral metal wire located in the inner area of ​​the polyurethane matrix, and the spacing ratio between the outer spiral metal wire and the inner spiral metal wire is determined according to the phase separation area distribution of the polyurethane matrix, comprises: Obtaining distribution density data of hard segments and soft segments in the polyurethane matrix; Divide the polyurethane matrix into regions according to the distribution density data to determine the spatial distribution diagrams of hard segment-rich regions and soft segment-rich regions; Calculating the volume ratio of the hard segment-rich region to the soft segment-rich region based on the spatial distribution diagram to obtain a phase separation degree parameter; Setting a spacing ratio between the outer spiral metal wire and the inner spiral metal wire according to the phase separation degree parameter, wherein the spacing ratio increases as the phase separation degree parameter increases; The outer layer spiral metal wires and the inner layer spiral metal wires are arranged according to the spacing ratio to obtain a spatial distribution structure.

4. The polyurethane material heat resistance detection method according to claim 1, characterized in that: The collecting of the temperature-strain correlation data on the surface of the test sample and the acquisition of the acoustic wave propagation attenuation characteristic data inside the test sample include: Preheating the test sample so that the surface temperature of the test sample reaches a preset initial temperature to obtain a thermal equilibrium state test sample; Acquiring temperature data points along the spiral channel direction of the thermal equilibrium state detection sample according to an equidistant distribution, and recording radial strain data at each data point and performing normalization processing to generate temperature-strain correlation data; Transmitting an ultrasonic signal to the thermal equilibrium state detection sample, and collecting attenuation data of the ultrasonic signal during the propagation process in the detection sample; The sound wave attenuation coefficients of different propagation paths are calculated according to the attenuation data to obtain the sound wave propagation attenuation characteristic data.

5. The polyurethane material heat resistance detection method according to claim 1, characterized in that: The initial temperature field distribution diagram is established based on the temperature-strain correlation data, a grid optimization process is performed on the area where the temperature change rate exceeds the set threshold, the material phase separation area is determined in combination with the sound wave propagation attenuation characteristic data, and microscopic thermal field distribution characteristic data is generated, including: According to the temperature-strain correlation data, a temperature field scanning path is established along the radial and circumferential directions of the inner and outer double-layer spiral channel structures, and a radial temperature distribution diagram is constructed with the intersection of the inner and outer double-layer spiral channel structures as a reference point to obtain an initial temperature field distribution diagram; Determine a temperature mutation region in the initial temperature field distribution map, compare the temperature change rate of the temperature mutation region with the phase transition temperature threshold of the polyurethane material, divide the key monitoring region, and perform grid refinement processing on the key monitoring region; Using the acoustic wave propagation attenuation characteristic data, acoustic analysis is performed on the key monitoring area, and according to the difference in attenuation characteristics of the hard segment and the soft segment in acoustic propagation, the spatial distribution characteristics of the phase separation area are determined; The spatial distribution characteristics of the phase separation region are fused with the grid refinement processing result to establish microscopic thermal field distribution characteristic data reflecting the local heat conduction heterogeneity.

6. The polyurethane material heat resistance detection method according to claim 5, characterized in that: Determining a temperature mutation region in the initial temperature field distribution map, comparing the temperature change rate of the temperature mutation region with the phase transition temperature threshold of the polyurethane material, dividing a key monitoring region, and performing grid refinement processing on the key monitoring region, includes: Performing temperature gradient analysis on the initial temperature field distribution diagram in the radial and circumferential directions of the inner and outer double-layer spiral channel structures, marking points where the temperature gradient exceeds a first preset threshold as temperature mutation points; Comparing the spatial distribution of the temperature mutation points with the positions of the inner and outer double-layer spiral channel structures to determine the temperature mutation area; Calculating the instantaneous temperature change rate in the temperature mutation region, comparing the instantaneous temperature change rate with the phase transition temperature threshold of the hard segment and the soft segment of the polyurethane material, and obtaining the phase transition sensitive region; Adaptively grid the phase change sensitive area and set the phase change sensitive area as the key monitoring area.

7. The polyurethane material heat resistance detection method according to claim 1, characterized in that: The detection sample is subjected to opposite thermal scanning by using a focusable laser beam, including an inward scanning process from the outer surface to the center of the sample and an outward scanning process from the center of the sample to the outer surface, and transient temperature response data in the two scanning processes are recorded, including: The focal position and power density of the adjustable focus laser beam are adjusted, and the partition is performed according to the pre-embedded position of the temperature-responsive metal wire in the inner and outer double-layer spiral channel structure to generate a sequence of opposite scanning paths; Performing an inward scan according to the opposite scanning path sequence, applying a first current sequence increasing from outside to inside to the temperature-responsive metal wire pre-buried in the inner and outer double-layer spiral channel structure, recording the composite thermal field temperature distribution during the inward scan, and obtaining inward temperature response data; Performing an outward scan according to the opposing scanning path sequence, applying a second current sequence increasing from inside to outside to the temperature-responsive metal wire pre-buried in the inner and outer double-layer spiral channel structure, recording the composite thermal field temperature distribution during the outward scan, and obtaining outward temperature response data; The inward temperature response data and the outward temperature response data are time-series aligned and compared to each other to determine the temperature response difference in the inner and outer double-layer spiral channel structure, thereby obtaining transient temperature response data.

8. The polyurethane material heat resistance detection method according to claim 7, characterized in that: The inward scanning is performed according to the opposite scanning path sequence, and a first current sequence increasing from outside to inside is applied to the temperature-responsive metal wire pre-buried in the inner and outer double-layer spiral channel structure, and the composite thermal field temperature distribution during the inward scanning process is recorded to obtain the inward temperature response data, including: Dividing the opposing scanning path sequence into a plurality of continuous spiral detection units, and determining a starting position and an ending position of each of the spiral detection units; Applying a first current sequence to the temperature-responsive metal wire, so that the metal wire in each of the spiral detection units reaches a phase transition temperature in sequence from outside to inside, forming a radially progressive first thermal field; Aligning the focus of the adjustable focus laser beam to each of the spiral detection units in sequence, and moving from outside to inside according to the opposite scanning path sequence to form a radially focused second thermal field; The composite temperature distribution of the first thermal field and the second thermal field is collected along the axial direction and the circumferential direction of the inner and outer double-layer spiral channel structure to obtain inward temperature response data.

9. The polyurethane material heat resistance detection method according to claim 1, characterized in that: The method of analyzing the time constant difference of the temperature response in two scanning directions based on the microscopic thermal field distribution characteristic data and the transient temperature response data, and determining the heat conduction characteristics caused by the microscopic phase separation of the hard segment and the soft segment inside the test sample, includes: Performing temperature gradient calculation on the microscopic thermal field distribution characteristic data, determining a temperature gradient threshold according to the partition characteristics of the inner and outer double-layer spiral channel structure, marking an area exceeding the temperature gradient threshold as a heat conduction abnormality area, and spatially registering the heat conduction abnormality area with a collection point of the transient temperature response data; Calculating the temperature response characteristic parameters of the abnormal heat conduction region during the inward scanning and outward scanning processes, including the temperature rise time and the temperature decay time, respectively, and generating a time constant distribution diagram reflecting the local thermal response characteristics of the material; Determine the temperature response rate distribution characteristics in the inner and outer double-layer spiral channel structure according to the time constant distribution diagram, classify different regions in combination with the phase change characteristics of the polyurethane material, and divide them into hard segment-dominated regions and soft segment-dominated regions; The temperature variation characteristics of the hard segment-dominated region and the soft segment-dominated region are analyzed to generate a thermal conductivity characteristic spectrum reflecting the degree of phase separation of the polyurethane material.

10. A polyurethane material heat resistance detection device, characterized in that: The polyurethane material heat resistance detection device adopts the polyurethane material heat resistance detection method according to any one of claims 1 to 9, and the polyurethane material heat resistance detection device comprises: A sample preparation module is used to embed a temperature-responsive metal wire in a polyurethane material, apply current stimulation to the metal wire to cause a phase change of the metal wire, and drive the polyurethane material to form an inner and outer double-layer spiral channel structure to obtain a test sample; A data acquisition module, used to acquire temperature-strain correlation data on the surface of the test sample and obtain sound wave propagation attenuation characteristic data inside the test sample; A temperature field analysis module is used to establish an initial temperature field distribution diagram based on the temperature-strain correlation data, perform grid optimization processing on the area where the temperature change rate exceeds the set threshold, determine the material phase separation area in combination with the sound wave propagation attenuation characteristic data, and generate microscopic thermal field distribution characteristic data; A thermal scanning control module, used for performing a counter-directional thermal scanning on the test sample by means of a focusable laser beam, including an inward scanning process from the outer surface to the center of the sample and an outward scanning process from the center of the sample to the outer surface, and recording transient temperature response data in the two scanning processes; The characteristic analysis module is used to analyze the time constant difference of the temperature response in two scanning directions based on the microscopic thermal field distribution characteristic data and the transient temperature response data, and determine the heat conduction characteristics caused by the microscopic phase separation of the hard segment and the soft segment inside the test sample.

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