Transient radiation temperature measuring device and calibration method for temperature rise of EVA composite shock-absorbing material under impact

Abstract

This invention discloses a transient radiation thermometry device and calibration method for measuring the temperature rise of EVA composite shock-absorbing materials under impact, belonging to the field of radiation thermometry technology. This invention aims to solve the problem of measurement distortion in transient temperature rise caused by the unknown and drastic dynamic changes in the surface emissivity of materials during impact. The device includes an impact loading module, a transient multispectral radiation acquisition module, a synchronous triggering module, and a data processing module that executes in-situ dynamic calibration and true temperature inversion algorithms. This algorithm constructs a spectral radiation intensity ratio model based on a reference wavelength, introducing physical constraints based on the unchanged surface chemical composition and stable emissivity spectral shape during the initial impact phase, parameterizing the dynamic emissivity of each wavelength as the product of a common amplitude factor and a relative shape factor.

Description

Technical Field

[0001] This invention relates to the field of radiation thermometry, and in particular to a transient radiation thermometry device and calibration method for measuring the temperature rise of EVA composite shock-absorbing material under impact. Background Technology

[0002] EVA composite shock-absorbing materials are widely used in sports protection, precision instrument packaging, and automotive collision buffering due to their excellent viscoelasticity and energy absorption capabilities. When subjected to high-speed impacts, the friction and viscous dissipation of the molecular chain segments within the material irreversibly convert most of the impact kinetic energy into heat, resulting in a dramatic transient temperature rise within the material over a very short time (milliseconds). Accurate measurement of this transient temperature rise is crucial for studying the material's shock-absorbing mechanism, evaluating its protective performance, and optimizing material composition and structural design. The amplitude, rate, and spatiotemporal distribution of the transient temperature rise directly relate to whether the material will fail due to overheating under impact, or whether its buffering performance is sufficient to protect the object being protected.

[0003] However, measuring the transient temperature rise of EVA composite shock-absorbing materials under impact faces significant challenges. Traditional contact-based temperature measurement methods, such as embedding thermocouples or resistance temperature detectors (RTDs), have inherent flaws. First, the physical intrusion of the sensor disrupts the material's original mechanical structure and stress field distribution, resulting in a measurement that does not reflect the material's true temperature rise. More critically, the thermal response time of these sensors is typically tens of milliseconds or even longer, far from keeping pace with the temperature rise front that lasts only a few milliseconds during the impact process. The measured results are severely attenuated and delayed, leading to erroneous data that fails to reflect the true transient physical process.

[0004] Non-contact radiation thermometry infers temperature by detecting the infrared radiation energy emitted from a material's surface, boasting extremely fast response times and theoretically capable of meeting the demands of millisecond-level transient measurements. However, directly applying it to the impact process of EVA composite shock-absorbing materials introduces a fundamental challenge: emissivity uncertainty. The basic physical law of radiation thermometry is Planck's law or its derivatives, where the material's radiance is a bivariate function of its true temperature and spectral emissivity. During impact, the surface state of the EVA composite shock-absorbing material undergoes dynamic and unpredictable drastic changes. Impact causes instantaneous changes in the orientation of the material's molecular chains, the formation of microcracks and wrinkles on the surface, changes in radiation penetration depth due to altered material transparency, and even the instantaneous generation and disappearance of the blackbody effect at the interface between the material and the impact head. All of this causes the material's effective spectral emissivity to fluctuate dramatically and non-monotonicly by tens of percentage points within milliseconds. Conventional radiation thermometry schemes, whether using a preset fixed emissivity or relying on an external blackbody reference, completely fail under such dynamic and extreme conditions. Using a fixed emissivity will introduce measurement errors of the same order of magnitude or even greater than the actual temperature rise due to emissivity fluctuations; while the external reference blackbody law loses its reference value because it cannot establish the same dynamic thermodynamics and surface state as the measured surface at the moment of impact.

[0005] Therefore, developing a non-invasive measurement device and calibration method that can eliminate the influence of dynamic changes in emissivity in real time during the impact process and accurately obtain the true transient temperature rise of EVA composite shock-absorbing materials is a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] To achieve the above objectives, the present invention provides a transient radiation temperature measurement device for EVA composite shock-absorbing material under impact temperature rise, comprising: The impact loading module is used to apply a preset energy to the EVA composite shock-absorbing material sample under test. and impact rate The impact; The transient multispectral radiation acquisition module is used to simultaneously acquire data on the change of spectral radiation intensity at at least three different center wavelengths emitted by the impacted area of ​​the tested EVA composite shock-absorbing material sample over time during the impact process. The synchronous triggering module is used to simultaneously trigger the impact action of the impact loading module and the data acquisition of the transient multispectral radiation acquisition module at the moment the impact begins. The data processing module is used to receive the spectral radiation intensity data output by the transient multispectral radiation acquisition module. The data processing module is configured to execute an in-situ dynamic calibration and real temperature inversion algorithm. The in-situ dynamic calibration and true temperature inversion algorithm includes: constructing a spectral radiation intensity ratio model based on a selected reference wavelength channel, independent of the absolute value of the material's own emissivity; introducing a physical constraint condition based on the EVA composite shock-absorbing material maintaining a stable surface chemical composition and emissivity spectral shape during impact-induced temperature rise, and dynamically adjusting the emissivity of each wavelength. Parameterized as a time-varying common amplitude factor Relative shape factor of each wavelength that does not change over time The product; utilizing a device integrated into the front end of the optical system, capable of instantaneous insertion and removal, and possessing a known spectral emissivity. An actively heated micro-reference surface performs in-situ system response calibration before impact and derives the relative form factor for each wavelength. The precise value; the stated Substituting the precise value into the ratio model, the true temperature at each sampling moment during the impact process is solved. .

[0007] Preferably, the transient multispectral radiation acquisition module includes at least three independent detection channels. Each detection channel consists of a narrowband filter with a different center wavelength located in the mid-infrared band of 3 to 5 micrometers and a high-speed infrared photodetector with a response time of less than 10 nanoseconds. All detection channels are coupled to an optical collection system composed of an off-axis parabolic mirror to ensure that the photons collected by all detection channels originate from the radiation energy of the same impacted area on the surface of the tested EVA composite shock-absorbing material sample at the same instant. The sampling rate of the transient multispectral radiation acquisition module is not less than 100 kHz.

[0008] Preferably, the spectral emissivity of the coating on the surface of the actively heated micro-reference surface is... The coating, its The value is not less than 0.92 in the 3-micron to 5-micron wavelength range, and is calibrated by a metrology institution at at least three center wavelengths; the actively heated micro-reference surface is integrated into a high-speed electric translation stage, which, upon receiving a command, can move the actively heated micro-reference surface into or out of the center of the field of view of the optical collection system within 50 milliseconds, and completely cover the impact area of ​​the tested EVA composite shock-absorbing material sample.

[0009] Preferably, when the data processing module executes the in-situ dynamic calibration and true temperature inversion algorithm, it first uses the data before the impact occurs. At all times, the room is at a known uniform room temperature. The radiation data collected under the condition, combined with the total spectral response coefficient of the optical-electronic system obtained by calibration of the actively heated micro-reference surface, is used. Calculate the emissivity at each wavelength in the initial state. and based on Calculate the normalized relative shape factor ,in Set to 1; subsequently, at any data acquisition moment during the impact process. Two independent equations for the ratio of spectral radiance intensity were constructed with respect to the unknown temperature. The functional relationship was determined, and the Levenberg-Marquardt iterative optimization algorithm was used to solve it, yielding the following results. The only solution.

[0010] Preferably, the total spectral response coefficient of the optical-electronic system The following steps are used to obtain the active heating micro-reference surface: Before the impact test, the surface is moved into the field of view and heated to a steady-state temperature close to the expected upper limit of the impact temperature rise. The steady-state temperature The radiation intensity is measured by a precision platinum resistance thermometer embedded within the actively heated miniature reference surface; the transient multispectral radiation acquisition module acquires the radiation intensity of each wavelength channel. The data processing module utilizes the formula Perform calculations, where The temperature was calculated based on Planck's law. The blackbody spectral radiance.

[0011] A transient radiation temperature measurement calibration method for the impact temperature rise of EVA composite shock-absorbing materials includes the following steps: Step 1: Fix the EVA composite shock-absorbing material sample on the sample stage, and set the impact energy of the impact loading module to [value missing]. and impact rate ; Step 2: Using the synchronous trigger module, the impact head contacts the surface of the EVA composite shock-absorbing material sample. At the same time, the impact loading module and the transient multispectral radiation acquisition module are started simultaneously; Step 3: During the impact process to During the time period, the transient multispectral radiation acquisition module continuously acquires radiation from the impacted area of ​​the EVA composite shock-absorbing material sample at a sampling rate of no less than 100 kHz, with at least three center wavelengths. , , The spectral radiance signal after the narrowband filter was used to obtain three sets of time-series data, denoted as follows: , , ; Step 4: The data processing module receives the three sets of time series data and processes each acquisition moment during the impact process. Perform in-situ dynamic calibration and true temperature inversion, among which ; Step 5: Repeat Step 4, iterating through all time points collected during the impact process, to obtain the true transient temperature change curve of the impacted area on the surface of the EVA composite shock-absorbing material sample throughout the entire impact process. .

[0012] Preferably, step 4 further includes: Step 4-1: Select the center wavelength as Using the reference wavelength channel as the reference wavelength channel, the ratio of the spectral radiance of other wavelength channels to that of the reference wavelength channel is constructed. ,in ; Step 4-2: Introduce constraints, which will be... Dynamic emissivity at each wavelength at any time Expressed as a common amplitude factor that varies over time Relative shape factor of each wavelength that does not change over time The product of, i.e. ,in ; Step 4-3: Substitute the constraints from Step 4-2 into the ratio expression from Step 4-1 to eliminate the common amplitude factor. The result contains only unknowns. and known quantities The system of equations; Step 4-4: Obtain the known quantities required in Step 4-3 The precise value is achieved by performing an in-situ calibration process on an alternative reference surface; Step 4-5: Obtain the data from step 4-4 and Substituting the precise value into the equations of step 4-3, an iterative optimization algorithm is used to find the temperature value that minimizes the difference between the two sides of the equations, which is then used as... The true temperature at any moment .

[0013] Preferably, the in-situ calibration process of the alternative reference surface described in step 4-4 further includes: Step 4-4a: Before the impact test begins, the actively heated micro-reference surface integrated at the front end of the device's optical system is moved into the center of the field of view of the optical collection system so that it completely covers the surface of the EVA composite shock-absorbing material sample under test. Step 4-4b: Heat the actively heated micro-reference surface to a stable temperature. And accurately read using an embedded precision platinum resistance thermometer ; Step 4-4c: The transient multispectral radiation acquisition module acquires the radiation intensity of each wavelength channel at this time, denoted as... ; Steps 4-4d: The data processing module calculates the wavelength of the optical-electronic system. Total spectral response coefficient at ,in The known spectral emissivity of the actively heated micro-reference surface, It is the radiance of the Planck blackbody; Step 4-4e: Remove the actively heated micro-reference surface out of the field of view to restore the EVA composite shock-absorbing material sample to its original position; Step 4-4f: In The sample was collected at a known room temperature just before the impact began. The radiation intensity of the EVA composite shock-absorbing material sample in each wavelength channel ; Step 4-4g: Calculate the spectral radiance of the EVA composite shock-absorbing material sample in its initial state. ; Step 4-4h: According to the formula The emissivity of each wavelength in the initial state can be calculated. ; Step 4-4i: with Using the channel as a reference, calculate the normalized relative shape factor. and set .

[0014] Preferably, the system of equations described in step 4-3 is specifically as follows: ; ; in, According to Planck's formula Calculated blackbody spectral radiance, The first radiation constant, is the second radiation constant.

[0015] Preferably, the iterative optimization algorithm described in steps 4-5 is the Levenberg-Marquardt algorithm, and the Levenberg-Marquardt algorithm solves... Objective function at time Defined as: ; The threshold for convergence of the Levonburg-Marquardt algorithm is set to a temperature change of less than 0.01 Kelvin.

[0016] The beneficial effects of this invention are: 1. This invention establishes a physical constraint model based on the initial stage of impact-induced temperature rise in EVA composite shock-absorbing materials where the surface chemical composition remains unchanged. It decouples the dynamic emissivity of each wavelength into the product of a time-varying common amplitude factor and a time-invariant relative shape factor, and deeply integrates this model with the multispectral ratio equation. This technique creatively transforms the ill-conditioned inversion problem of traditional radiation thermometry, where both temperature and absolute emissivity are unknown, into a solvable positive definite problem with only temperature as an unknown. Therefore, even when the absolute emissivity undergoes drastic and unknown dynamic changes, the true temperature can still be consistently calculated from the measurement data itself. Compared to conventional methods relying on a fixed emissivity assumption or an external reference, this invention completely eliminates measurement errors introduced by emissivity fluctuations, achieving high-fidelity, non-invasive measurement of millisecond-level impact transient temperature rises, providing unprecedented characterization capabilities for the dynamics of shock-absorbing materials. 2. This invention designs an actively heated micro-reference surface integrated into the front end of an optical system and capable of instantaneous insertion and removal, and establishes a corresponding in-situ calibration strategy for alternative reference surfaces. This integrates the calibration of the system's absolute spectral response coefficient with the acquisition of the sample's intrinsic emissivity spectral shape factor. This technique, under the same optical path, measurement geometry, and environmental background, completes self-calibration and closed-loop control instantaneously before the impact occurs, precisely locking the initial spectral constraint parameters necessary for subsequent dynamic temperature inversion. Compared to traditional separate calibration schemes using external blackbody furnaces, this invention avoids optical path differences and background radiation interference, ensuring the absolute accuracy of system calibration and material parameter extraction from the source, laying a solid foundation for the accuracy of dynamic temperature measurement. 3. This invention achieves a synergistic effect by deeply integrating multispectral high-speed radiation acquisition hardware with an intelligent constraint algorithm based on the transient physical properties of materials, resulting in a synergistic technical outcome where "1+1>2". The device provides the algorithm with a clean, time-consistent multispectral radiation intensity time series; the algorithm, in turn, empowers the device to extract the physical essence of temperature from data that may appear distorted due to emissivity fluctuations. This overall approach makes it possible to accurately reconstruct the complete transient temperature rise curve of EVA composite shock-absorbing materials during a single impact. The measurement results are unaffected by changes in specific conditions such as impact energy and velocity, exhibiting strong robustness and universality, and providing reliable data support for related materials science and engineering applications. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the frame of the device of the present invention. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should also be noted that, to make the embodiments more comprehensive, the following embodiments are the best and preferred embodiments, and those skilled in the art can use other alternative methods to implement some well-known technologies; moreover, the accompanying drawings are only for more specific description of the embodiments and are not intended to specifically limit the present invention.

[0020] Please see Figure 1 The technical solution proposed in this invention aims to solve the core measurement problem of EVA composite shock-absorbing materials under impact loads, where the surface spectral emissivity undergoes unknown and drastic dynamic changes, making it impossible for conventional radiation thermometry methods to accurately obtain the transient temperature rise of the material. To address this problem, this invention provides a device and method that deeply integrates an in-situ dynamic calibration strategy. The fundamental idea is to abandon the reliance on preset absolute emissivity values ​​or external references in traditional methods, and instead utilize a physical characteristic inherent in EVA composite shock-absorbing materials during the specific transient process of impact-induced temperature rise—that is, the surface chemical composition does not change in a short time, thus maintaining a stable spectral shape of its emissivity, while the absolute amplitude of the emissivity can scale synchronously with surface physical roughness, cracks, and other conditions—to construct a self-consistent constraint. This constraint transforms the ill-conditioned problem in multispectral radiation measurement signals, which was originally unsolvable due to the dual unknowns of temperature and emissivity, into a solvable positive definite problem, thereby enabling real-time and dynamic analysis of the true temperature value.

[0021] The key technical means and their internal working mechanism adopted in this invention to solve the problem will be described in detail below to ensure the clarity and completeness of the technical solution.

[0022] First, regarding the core constraints of this invention. Conventional multispectral thermometry typically assumes a fixed functional relationship (e.g., linear, exponential) between emissivity and wavelength. However, during impact, cracks, wrinkles, and changes in molecular chain orientation occur on the material surface. These changes in physical state collectively enhance or weaken the material's ability to emit infrared radiation, which is intuitively manifested as a shift or scaling of the spectral emissivity curve along the vertical axis, rather than a distortion of the spectral shape. This invention captures and quantifies this physical essence. We express it as: at any moment of impact... Arbitrary wavelength Dynamic emissivity at It can be decoupled into the product of two independent parts, namely a time-varying common amplitude factor. A relative shape factor that does not change over time and is determined solely by the intrinsic properties of the material in its initial thermodynamic state. .in, This reflects the synchronous and proportional modulation effect of the impact-induced change in the surface physical state on the absolute values ​​of emissivity across all wavelengths; and This represents the intrinsic emissivity spectral fingerprint of the material when it is not subjected to impact disturbance. The physical basis for this decoupling lies in the fact that the adiabatic compression and viscous heat dissipation in the initial stage of impact is a sub-millisecond to millisecond-scale physical process, much faster than the time scale required for chemical composition changes such as oxidation and pyrolysis on the material surface. Therefore, this constraint is not a forced mathematical assumption, but a precise characterization of the time scale separation of the physicochemical processes in the initial stage of impact, forming the physical cornerstone of the entire calibration method.

[0023] Secondly, regarding the design of the integrated "instantaneously movable, actively heated miniature reference surface" in the device and its synergistic relationship with the in-situ calibration algorithm, conventional radiation thermometry system calibration typically points the detector to an external blackbody furnace. This calibration method introduces complex and unknown optical path differences and background radiation interference between the blackbody furnace and the sample under test, making high-precision in-situ calibration impossible. This invention creatively integrates a miniaturized, controllably heated, and precisely temperature-measuring reference radiation source into the front end of the device's optical system via a high-speed electric translation stage. The significant innovation of this design lies in its ability to allow for absolute spectral responsivity calibration of the detector system instantaneously before the start of the impact experiment, under the same optical path, measurement geometry, and environmental background. Specifically, it uses a known spectral emissivity... The reference surface is heated to a known temperature. The radiation signal received by the detector directly reflects the transmission characteristics of the entire link, from emission from the reference surface, through collection and transmission via an identical optical system, to the final response of the detector, thereby accurately calculating the total spectral response coefficient of the system. Then, it instantly moves away from the reference plane, at a known room temperature. The sample was measured, by By acting as a bridge, the spectral radiance of the sample in its initial state can be absolutely quantified, and the intrinsic shape factor of the material can be extracted for the first time with high precision. This process combines the traditionally separate "system calibration" and "material parameter acquisition" into one, forming a self-calibration closed loop that is completed instantaneously before the impact occurs. Its accuracy is unmatched by any external calibration method.

[0024] Finally, regarding the inversion solution mechanism for the true temperature. When the shape factor is obtained... Once this value is determined, the ratio equations at any given moment during the impact process consist only of temperature. One unknown. This invention employs the Levenberg-Marquardt iterative optimization algorithm to solve this overdetermined system of equations. This is because the Planck function is a highly nonlinear function with respect to temperature and cannot be solved analytically directly. By constructing a least-squares objective function, the algorithm can stably and quickly converge to the true temperature value. Theoretically, two independent ratio equations can solve for one unknown. This invention uses at least three wavelength channels and constructs two ratio equations to form an overdetermined system. This is not only for solving the problem but, more importantly, to utilize redundant information to smooth measurement noise and enhance the robustness and accuracy of the inversion results. This complete chain, from multispectral ratio data, through a physical constraint model, to the final temperature solution, constitutes the complete methodology of this invention from data to physical insights. Example

[0025] This embodiment measures the transient temperature rise of an EVA composite shock-absorbing material sample used in sports protective equipment under drop hammer impact conditions. The sample dimensions are 100 mm × 100 mm × 20 mm.

[0026] The first step is device preparation and initial setup.

[0027] The EVA composite shock-absorbing material sample was fixed to the sample stage of the device using clamps, ensuring that its upper surface, which would bear the impact, was horizontal and free of prestress. The impact loading module used was a drop-weight impact system, and its impact energy was set. Impact rate The impact head is a hemispherical steel punch with a diameter of 20 mm. An integrated piezoelectric force sensor is used to accurately determine the instant the impact head contacts the sample surface. time.

[0028] Activate the transient multispectral radiation acquisition module. This module contains three independent detection channels with center wavelengths of [missing information]. , and Each channel consists of a narrowband filter coupled to a high-speed mercury cadmium telluride infrared photodetector with a response time of 8 nanoseconds. All detection channels are focused onto the center of the impacted area of ​​the sample through a shared off-axis parabolic mirror optical collection system, forming a measurement spot with a diameter of approximately 1 mm. The sampling rate of this module is set to 200 kHz. The entire device is placed in a constant temperature and humidity laboratory at 22.5°C and 40% humidity to stabilize the background environment.

[0029] The second step is to perform in-situ calibration on the alternative reference surface to obtain the shape factor. and system response coefficient .

[0030] This process is performed before the actual impact. First, the data processing module sends commands to the high-speed motorized translation stage that controls the actively heated micro-reference surface. The micro-reference surface substrate is aluminum nitride ceramic, coated with a high-emissivity black paint called NEXTEL Velvet811-21, whose spectral emissivity... The wavelength range of 3 to 5 micrometers is calibrated by metrology institutions, with specific values ​​as follows: , , Within 45 milliseconds of receiving the command, the translation stage smoothly moves the reference plane into the center of the field of view of the optical collection system, ensuring that it completely covers the area above the impacted sample.

[0031] Once the reference surface is in place, the temperature control circuit of its integrated thin-film heater and precision platinum resistance thermometer (Pt100, accuracy ±0.1℃) is activated to rapidly heat the reference surface to a steady-state temperature close to the expected upper limit of the shock temperature rise. (i.e., 85.0℃), and maintained stably. At this time, the transient multispectral radiation acquisition module recorded the radiation intensity of each wavelength channel, which were respectively , , The data processing module receives this data and combines it with known information. and Perform the calculation.

[0032] First, calculate the temperature according to Planck's law. Blackbody spectral radiance The formula used is: ; Among them, the first radiation constant Second radiation constant The calculation yielded: ; ; ; Then, calculate the total spectral response coefficient of the system. The calculation formula is: Substituting the data, we get: ; ; ; After the calculation is completed, a command is sent again to the high-speed electric translation stage to move the actively heated micro reference surface out of the field of view within 45 milliseconds, so that the impacted area of ​​the EVA composite shock-absorbing material sample is re-exposed to the field of view of the optical system.

[0033] At this time, the sample is at ambient room temperature. (i.e., 22.5℃), the data acquisition system recorded the temperature before the impact occurred. The instantaneous radiation intensities are respectively , , .

[0034] Using the obtained Converting radiation intensity into the sample's own spectral radiance: ; ; ;

[0035] ; According to the relation Calculate the initial state emissivity. First, calculate... Blackbody spectral radiance at time: ; ; ; Then calculate backwards : ; ; ; Finally, with Using the channel as a reference, calculate the normalized relative shape factor. :

[0036] ; ; At this point, the in-situ calibration is complete, and the key unknown shape parameters have been determined. and It has been precisely locked to versions 1.013 and 1.047.

[0037] The third step is to perform impact and data collection simultaneously.

[0038] The pre-trigger logic of the synchronous trigger module is activated. This module defines the moment when the signal transition edge (threshold set to 0.5 Newtons) of the force sensor built into the impact head is triggered. .exist At the same time, the synchronous trigger module simultaneously activates the data acquisition system and releases the drop hammer. The impact loading module impacts the sample at a set energy of 50 joules and a speed of 3.0 meters per second. The transient multispectral radiation acquisition module continuously records the data from the sample at a sampling rate of 200 kHz. to Three sets of spectral radiation intensity voltage signal sequences over a time period , , .

[0039] The fourth step is to invert the dynamic real temperature point by point.

[0040] After receiving the complete 10-millisecond time series data, the data processing module processes each sampling moment... Perform temperature inversion. Using a point near the peak impact time... For example, the collected radiation intensity is , , .

[0041] First, convert to spectral radiance. : ; ; ; Then, the spectral radiance ratio is constructed to solve for the temperature. (Selected) Using the reference wavelength, calculate the measured ratio: ; ; Based on the core emissivity model of this invention, emissivity is expressed as: Spectral radiance Can be written as In the ratio, the common amplitude factor Eliminated, substituted with a known shape factor , , The result contains a unique unknown. The theoretical ratio equation: ; ; The data processing module calls the Levenberg-Marquardt iterative optimization algorithm to solve the problem. The following objective function is made so that Minimize: ;

[0042] During the algorithm iteration process, The temperature estimate is continuously updated using Planck's formula with each iteration. The convergence threshold is set to a temperature change between two consecutive iterations that is less than 0.01 Kelvin. The algorithm converges after 5 iterations, finally obtaining the true temperature at that moment. .

[0043] Step 5: Generate the transient temperature rise curve.

[0044] The data processing module repeats the process from step four, processing the data from... arrive Temperature inversion was performed on all 2000 sampling points one by one to obtain the true transient temperature change curve of the impacted area on the surface of the EVA composite shock-absorbing material during the entire impact process. .

[0045] Comparative Example To highlight the beneficial effects of the technical solution in this embodiment, a typical conventional two-color thermometry method is used as a comparative example to process data from the same impact process. The conventional two-color thermometry method assumes that the emissivity of the material is equal at both measurement wavelengths, i.e., it assumes... Directly utilize and The temperature is inverted by the ratio of the two channels. The solution equation is: ; Using the same method as the embodiments of the present invention and The passage is The measured ratio of the radiation intensity data at time t was calculated to be 0.7065. The inversion temperature was obtained by iteratively solving the equation. .

[0046] For quantitative comparison, this embodiment sets a "true reference," which is measured under the same impact conditions by embedding an ultrafast thin-film thermocouple (response time better than 1 microsecond) inside the sample. Its reading at 2.5 milliseconds is 366.15 Kelvin. Although this contact method has systematic biases due to the damage to the material structure, its time response capability makes it a reference benchmark for dynamic trends.

[0047] Table 1 shows a comparison of the measurement results of the method of this invention, the conventional two-color method, and the true reference at several key moments in the impact process.

[0048]

[0049] Results Analysis The comparison data in the table above clearly shows that the conventional two-color thermometry method, which uses a fixed emissivity assumption, completely ignores the differences in the shape of the EVA material's emissivity spectrum and the dynamic scaling of its absolute value during the impact process. Therefore, the temperature values ​​it retrieves are severely underestimated; for example, the deviation at 2.5 milliseconds is as high as 23.64 Kelvin. Furthermore, the temperature change during the entire impact process is far smaller than the actual situation, completely failing to reflect the dramatic temperature rise caused by the conversion of impact energy into heat. The fundamental error of this method lies in forcibly ignoring the physical fact that emissivity changes with wavelength, rendering the temperature measurement results physically meaningless.

[0050] Conversely, the technical solution proposed in this invention obtains the intrinsic emissivity spectral shape factor of the material through precise pre-calibration in situ and, combined with the unique physical constraints of the transient impact process, successfully achieves accurate temperature inversion under unknown dynamic emissivity. At several critical moments, the maximum deviation between the measurement results of this invention and the true reference does not exceed 1.5 Kelvin, and the relative deviation is less than 0.5%, fully demonstrating its ability to accurately capture the true transient temperature rise during the impact process and solving a long-standing measurement technical problem in this field.

[0051] This invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of this invention. To provide the public with a thorough understanding of this invention, specific details are described in detail in the following preferred embodiments; however, those skilled in the art will fully understand the invention even without these details. Furthermore, to avoid unnecessary misunderstanding of the essence of this invention, well-known methods, processes, procedures, components, and circuits are not described in detail.

[0052] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A transient radiation thermometry device for measuring the temperature rise of an EVA composite shock absorbing material upon impact, characterized in that, include: The impact loading module is used to apply a preset energy to the EVA composite shock-absorbing material sample under test. and impact rate The impact; The transient multispectral radiation acquisition module is used to simultaneously acquire data on the change of spectral radiation intensity at at least three different center wavelengths emitted by the impacted area of ​​the tested EVA composite shock-absorbing material sample over time during the impact process. The synchronous triggering module is used to simultaneously trigger the impact action of the impact loading module and the data acquisition of the transient multispectral radiation acquisition module at the moment the impact begins. The data processing module is used to receive the spectral radiation intensity data output by the transient multispectral radiation acquisition module. The data processing module is configured to execute an in-situ dynamic calibration and real temperature inversion algorithm. The in-situ dynamic calibration and true temperature inversion algorithm includes: constructing a spectral radiation intensity ratio model based on a selected reference wavelength channel, independent of the absolute value of the material's own emissivity; introducing a physical constraint condition based on the EVA composite shock-absorbing material maintaining a stable surface chemical composition and emissivity spectral shape during impact-induced temperature rise, and dynamically adjusting the emissivity of each wavelength. Parameterized as a time-varying common amplitude factor Relative shape factor of each wavelength that does not change over time The product; utilizing a device integrated into the front end of the optical system, capable of instantaneous insertion and removal, and possessing a known spectral emissivity. An actively heated micro-reference surface performs in-situ system response calibration before impact and derives the relative form factor for each wavelength. The precise value; the stated Substituting the precise value into the ratio model, the true temperature at each sampling moment during the impact process is solved. .

2. The transient radiation temperature measurement device for EVA composite shock-absorbing material under impact temperature rise according to claim 1, characterized in that, The transient multispectral radiation acquisition module includes at least three independent detection channels. Each detection channel consists of a narrowband filter with a different center wavelength in the mid-infrared band of 3 to 5 micrometers and a high-speed infrared photodetector with a response time of less than 10 nanoseconds. All detection channels are coupled to an optical collection system composed of an off-axis parabolic mirror to ensure that the photons collected by all detection channels originate from the radiation energy of the same impacted area on the surface of the tested EVA composite shock-absorbing material sample at the same instant. The sampling rate of the transient multispectral radiation acquisition module is not less than 100 kHz.

3. The transient radiation temperature measurement device for EVA composite shock-absorbing material under impact temperature rise according to claim 2, characterized in that, The spectral emissivity of the coating on the surface of the actively heated micro-reference surface is... The coating, its The value is not less than 0.92 in the 3-micron to 5-micron wavelength range, and is calibrated by a metrology institution at at least three center wavelengths; the actively heated micro-reference surface is integrated on a high-speed electric translation stage, which, upon receiving a command, can move the actively heated micro-reference surface into or out of the center of the field of view of the optical collection system within 50 milliseconds, and completely cover the impact area of ​​the tested EVA composite shock-absorbing material sample.

4. The transient radiation temperature measurement device for EVA composite shock-absorbing material under impact temperature rise according to claim 1, characterized in that, When the data processing module executes the in-situ dynamic calibration and true temperature inversion algorithm, it first uses the data before the impact occurs. At all times, the room is at a known uniform room temperature. The radiation data collected under the condition, combined with the total spectral response coefficient of the optical-electronic system obtained by calibration of the actively heated micro-reference surface, is used. Calculate the emissivity at each wavelength in the initial state. and based on Calculate the normalized relative shape factor ,in Set to 1; Subsequently, at any sampling moment during the impact process Two independent equations for the ratio of spectral radiance intensity were constructed with respect to the unknown temperature. The functional relationship was determined, and the Levenberg-Marquardt iterative optimization algorithm was used to solve it, yielding the following results. The only solution.

5. The transient radiation temperature measurement device for EVA composite shock-absorbing material under impact temperature rise according to claim 4, characterized in that, The total spectral response coefficient of the optical-electronic system The following steps are used to obtain the active heating micro-reference surface: Before the impact test, the surface is moved into the field of view and heated to a steady-state temperature close to the expected upper limit of the impact temperature rise. The steady-state temperature The radiation intensity is measured by a precision platinum resistance thermometer embedded within the actively heated miniature reference surface; the transient multispectral radiation acquisition module acquires the radiation intensity of each wavelength channel. The data processing module utilizes the formula Perform calculations, where The temperature was calculated based on Planck's law. The blackbody spectral radiance.

6. A transient radiation temperature measurement calibration method for the impact temperature rise of EVA composite shock-absorbing material, used in the apparatus described in any one of claims 1 to 5, characterized in that, Includes the following steps: Step 1: Fix the EVA composite shock-absorbing material sample on the sample stage, and set the impact energy of the impact loading module to [value missing]. and impact rate ; Step 2: Using the synchronous trigger module, the impact head contacts the surface of the EVA composite shock-absorbing material sample. At the same time, the impact loading module and the transient multispectral radiation acquisition module are started simultaneously; Step 3: During the impact process to During the time period, the transient multispectral radiation acquisition module continuously acquires radiation from the impacted area of ​​the EVA composite shock-absorbing material sample at a sampling rate of no less than 100 kHz, with at least three center wavelengths... , , The spectral radiance signal after the narrowband filter was used to obtain three sets of time-series data, denoted as follows: , , ; Step 4: The data processing module receives the three sets of time series data and processes each acquisition moment during the impact process. Perform in-situ dynamic calibration and true temperature inversion, among which ; Step 5: Repeat Step 4, iterating through all time points collected during the impact process, to obtain the true transient temperature change curve of the impacted area on the surface of the EVA composite shock-absorbing material sample throughout the entire impact process. .

7. The transient radiation temperature measurement calibration method for the impact temperature rise of EVA composite shock-absorbing material according to claim 6, characterized in that, Step 4 further includes: Step 4-1: Select the center wavelength as Using the reference wavelength channel as the reference wavelength channel, the ratio of the spectral radiance of other wavelength channels to that of the reference wavelength channel is constructed. ,in ; Step 4-2: Introduce constraints, which will be... Dynamic emissivity at each wavelength at any time Expressed as a common amplitude factor that varies over time Relative shape factor of each wavelength that does not change over time The product of, i.e. ,in ; Step 4-3: Substitute the constraints from Step 4-2 into the ratio expression from Step 4-1 to eliminate the common amplitude factor. The result contains only unknowns. and known quantities The system of equations; Step 4-4: Obtain the known quantities required in Step 4-3 The precise value is achieved by performing an in-situ calibration process on an alternative reference surface; Step 4-5: Obtain the data from step 4-4 and Substituting the precise value into the equations of step 4-3, an iterative optimization algorithm is used to find the temperature value that minimizes the difference between the two sides of the equations, which is then used as... The true temperature at any moment .

8. The transient radiation temperature measurement calibration method for the impact temperature rise of EVA composite shock-absorbing material according to claim 7, characterized in that, The in-situ calibration process for the alternative reference surface described in step 4-4 further includes: Step 4-4a: Before the impact test begins, the actively heated micro-reference surface integrated at the front end of the device's optical system is moved into the center of the field of view of the optical collection system so that it completely covers the surface of the EVA composite shock-absorbing material sample under test. Step 4-4b: Heat the actively heated micro-reference surface to a stable temperature. And accurately read using an embedded precision platinum resistance thermometer ; Step 4-4c: The transient multispectral radiation acquisition module acquires the radiation intensity of each wavelength channel at this time, denoted as... ; Steps 4-4d: The data processing module calculates the wavelength of the optical-electronic system. Total spectral response coefficient at ,in The known spectral emissivity of the actively heated micro-reference surface, It is the radiance of the Planck blackbody; Step 4-4e: Remove the actively heated micro-reference surface out of the field of view to restore the EVA composite shock-absorbing material sample to its original position; Step 4-4f: In The sample was collected at a known room temperature just before the impact began. The radiation intensity of the EVA composite shock-absorbing material sample in each wavelength channel ; Step 4-4g: Calculate the spectral radiance of the EVA composite shock-absorbing material sample in its initial state. ; Step 4-4h: According to the formula The emissivity of each wavelength in the initial state can be calculated. ; Step 4-4i: with Using the channel as a reference, calculate the normalized relative shape factor. and set .

9. The transient radiation temperature measurement calibration method for the impact temperature rise of EVA composite shock-absorbing material according to claim 8, characterized in that, The system of equations mentioned in step 4-3 is specifically as follows: ; ; in, According to Planck's formula Calculated blackbody spectral radiance, The first radiation constant, is the second radiation constant.

10. The transient radiation temperature measurement calibration method for the impact temperature rise of EVA composite shock-absorbing material according to claim 7, characterized in that, The iterative optimization algorithm described in steps 4-5 is the Levenberg-Marquardt algorithm, which solves the problem. Objective function at time Defined as: ; The threshold for convergence of the Levonburg-Marquardt algorithm is set to a temperature change of less than 0.01 Kelvin.

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