Performance test method and test equipment for polyurethane foaming

Abstract

The invention discloses a polyurethane foaming performance test method and test equipment, and the method comprises the steps: applying pressure to a test sample piece until the pressure value of the test sample piece reaches a preset pressure threshold value, and the test sample piece is polyurethane foaming; when it is determined that the stress relaxation of the test sample reaches a balanced state, applying a test vibration signal to the test sample to obtain a target pressure value and a target displacement value of the test sample under the test vibration signal; and testing the polyurethane foaming performance based on the target pressure value and the target displacement value. According to the testing method, the polyurethane foaming dynamic performance testing method can be standardized, and a basis is provided for subsequent dynamic performance testing.

Description

Technical Field

[0001] The invention relates to the technical field of performance testing, in particular to a performance testing method for polyurethane foaming and a performance testing device for polyurethane foaming. Background Art

[0002] Flexible molded polyurethane foam has become the preferred material for automotive seat applications. At present, the industry has formulated many standards and test methods for polyurethane foam for seats to evaluate its quasi-static properties and static comfort. For example, the stress-strain curve of polyurethane foam for seats can be tested. Through this curve, the hysteresis loss rate, depression ratio, initial hardness index, modulus rule index, etc. of polyurethane foam for seats can be further analyzed; the rebound height of polyurethane foam for seats can be tested, and the rebound rate can be calculated to reflect the rebound performance of polyurethane foam. However, the above tests or standards do not consider the performance of polyurethane foam for seats under dynamic conditions. In actual driving, drivers or passengers are often disturbed by dynamic loads, so it is particularly important to examine the dynamic performance of polyurethane foam for seats. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the first purpose of the present invention is to propose a performance test method for polyurethane foaming, applying pressure to a test sample until the pressure value of the test sample reaches a preset pressure threshold, wherein the test sample is polyurethane foaming; when it is determined that the stress relaxation of the test sample has reached an equilibrium state, applying a test vibration signal to the test sample to obtain a target pressure value and a target displacement value of the test sample under the test vibration signal; testing the performance of polyurethane foaming based on the target pressure value and the target displacement value, thereby standardizing the dynamic performance test method of polyurethane foaming and providing a basis for subsequent dynamic performance testing.

[0004] The second object of the present invention is to provide a performance testing device for polyurethane foaming.

[0005] To achieve the above-mentioned purpose, the first aspect of the present invention proposes a method for testing the performance of polyurethane foam, the method comprising: applying pressure to a test sample until the pressure value of the test sample reaches a preset pressure threshold, wherein the test sample is polyurethane foam; when it is determined that the stress relaxation of the test sample has reached an equilibrium state, applying a test vibration signal to the test sample to obtain a target pressure value and a target displacement value of the test sample under the test vibration signal; and testing the performance of the polyurethane foam based on the target pressure value and the target displacement value.

[0006] According to the performance test method of polyurethane foaming of the embodiment of the present invention, pressure is applied to the test sample until the pressure value of the test sample reaches a preset pressure threshold, wherein the test sample is polyurethane foaming; when it is determined that the stress relaxation of the test sample has reached an equilibrium state, a test vibration signal is applied to the test sample to obtain a target pressure value and a target displacement value of the test sample under the test vibration signal; and the performance of the polyurethane foaming is tested based on the target pressure value and the target displacement value. Therefore, the method can standardize the dynamic performance test method of polyurethane foaming and provide a basis for subsequent dynamic performance testing.

[0007] In addition, the performance testing method of polyurethane foam according to the above embodiment of the present invention may also have the following additional technical features:

[0008] According to an embodiment of the present invention, the test vibration signal is a single-axis swept frequency excitation.

[0009] According to one embodiment of the present invention, applying a test vibration signal to the test sample includes: applying a sinusoidal swept frequency excitation with a preset frequency range and a preset acceleration to the test sample.

[0010] According to one embodiment of the present invention, the performance of the polyurethane foam is tested based on the target pressure value and the target displacement value, including: performing Fourier transform on the target pressure value and the target displacement value to obtain frequency domain data; and testing the performance of the polyurethane foam based on the frequency domain data.

[0011] According to one embodiment of the present invention, the performance of the polyurethane foam is tested based on the frequency domain data, including: acquiring at least one of dynamic stiffness, dynamic damping, energy dissipation coefficient, vibration transfer coefficient and vibration comfort coefficient according to the frequency domain data; and determining the performance of the polyurethane foam according to at least one of the dynamic stiffness, the dynamic damping, the energy dissipation coefficient, the vibration transfer coefficient and the vibration comfort coefficient.

[0012] According to an embodiment of the present invention, determining that the stress relaxation of the test sample has reached a balanced state includes: when the pressure value does not change within a preset time period, determining that the stress relaxation of the test sample has reached a balanced state.

[0013] According to one embodiment of the present invention, the method further includes: applying pressure to the test sample at a preset speed until the thickness of the test sample reaches a preset thickness and then stopping the pressure to obtain a debugging pressure value-debugging displacement value curve, and repeating the process a preset number of times until a plurality of the debugging pressure value-debugging displacement value curves are obtained.

[0014] According to an embodiment of the present invention, the method further comprises: when the error between the plurality of debugging pressure-debugging displacement value curves is less than a preset error value, determining that the test requirement is met.

[0015] To achieve the above-mentioned purpose, the second aspect of the present invention proposes a performance testing device for polyurethane foam, the device comprising: a pressure head, a signal applicator and a controller, wherein the controller is used to control the pressure head to apply pressure to a test sample until the pressure value of the test sample reaches a preset pressure threshold and stops, wherein the test sample is polyurethane foam; when it is determined that the stress relaxation of the test sample reaches an equilibrium state, the signal applicator is controlled to apply a test vibration signal to the test sample to obtain a target pressure value and a target displacement value of the test sample under the test vibration signal; and the performance of the polyurethane foam is tested based on the target pressure value and the target displacement value.

[0016] According to the performance testing equipment for polyurethane foaming of the embodiment of the present invention, the controller is used to control the pressure head to apply pressure to the test sample until the pressure value of the test sample reaches a preset pressure threshold, wherein the test sample is polyurethane foaming, and when it is determined that the stress relaxation of the test sample has reached an equilibrium state, the signal applicator is controlled to apply a test vibration signal to the test sample to obtain the target pressure value and target displacement value of the test sample under the test vibration signal, and the performance of the polyurethane foaming is tested based on the target pressure value and the target displacement value. Therefore, the testing equipment can standardize the dynamic performance testing method of polyurethane foaming and provide a basis for subsequent dynamic performance testing.

[0017] In addition, the performance testing equipment for polyurethane foaming according to the above embodiment of the present invention may also have the following additional technical features:

[0018] According to one embodiment of the present invention, it further includes: a displacement sensor and a pressure sensor arranged on the pressure head, wherein the pressure sensor is used to obtain the pressure value applied by the pressure head to the test sample; and the displacement sensor is used to obtain the displacement value of the test sample under the pressure value.

[0019] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a flow chart of a method for testing the performance of polyurethane foaming according to an embodiment of the present invention;

[0021] Figure 2A schematic diagram of a dynamic stiffness calculation curve of foam samples with different hardness according to an embodiment of the present invention;

[0022] Figure 3 A schematic diagram of a dynamic stiffness calculation curve of foam samples with different thicknesses according to an embodiment of the present invention;

[0023] Figure 4 A schematic diagram of a dynamic damping calculation curve of foam samples with different hardness according to an embodiment of the present invention;

[0024] Figure 5 A schematic diagram of a dynamic damping calculation curve of foam samples with different thicknesses according to an embodiment of the present invention;

[0025] Figure 6 A schematic diagram of a calculation curve of energy dissipation coefficients of foam samples with different hardness according to an embodiment of the present invention;

[0026] Figure 7 A schematic diagram of a calculation curve of energy dissipation coefficients of foam samples with different thicknesses according to an embodiment of the present invention;

[0027] Figure 8 A schematic diagram of a calculation curve of vibration transfer coefficients of foam samples with different hardnesses according to an embodiment of the present invention;

[0028] Fig. 9 A schematic diagram of a calculation curve of vibration transfer coefficients of foam samples with different thicknesses according to an embodiment of the present invention;

[0029] Fig.10 A flow chart of a method for testing the performance of polyurethane foam according to a specific example of the present invention;

[0030] Fig.11 A block diagram of a performance testing device for polyurethane foaming according to an embodiment of the present invention;

[0031] Fig.12 It is a schematic structural diagram of a performance testing device for polyurethane foaming according to a specific example of the present invention. DETAILED DESCRIPTION

[0032] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0033] In the current related technologies, the performance testing and evaluation of polyurethane foam used in seats mainly focus on static and quasi-static conditions, including ball drop rebound rate, hysteresis loss rate, depression ratio, etc. Ball drop rebound is to calculate the percentage of the maximum height of the steel ball rebound and the height of the steel ball falling, i.e. the rebound rate, by letting a steel ball of a given diameter and mass fall freely on the polyurethane foam sample at a specified height. The rebound rate is used to represent the rebound performance of polyurethane foam. Generally, the rebound range of a small ball should be between 50% and 70%. The hysteresis loss rate is the ratio of the work lost when the polyurethane foam rebounds in the static stiffness test to the work used during compression. The hysteresis rate between 15-30% is a relatively ideal range. When the hysteresis rate is less than 15%, it indicates that the polyurethane foam has a very poor ability to absorb energy. When the hysteresis loss rate is greater than 30%, the polyurethane foam will easily collapse when sitting, or the fatigue loss will be relatively large, which is not conducive to maintaining the durability of the polyurethane foam. The depression ratio is the ratio of the force generated when the sample is pressed 65% to the force generated when the sample is pressed 25% under specified pressure conditions. It can reflect the ability of polyurethane foam to withstand loads. Many studies have shown that a higher depression ratio can achieve better static comfort. However, the above technical solutions are mainly focused on the testing and evaluation of the static or quasi-static performance of polyurethane foam used in seats, without considering its performance under dynamic conditions. In actual driving, drivers or passengers are often disturbed by dynamic loads, so it is particularly important to examine the dynamic performance of polyurethane foam used in seats.

[0034] To this end, this application proposes a performance test method for polyurethane foaming, which improves the evaluation system of polyurethane foaming for seats, evaluates based on quantifiable standards and data, avoids the influence of subjective factors, has high fairness and accuracy, effectively improves evaluation efficiency, avoids waste of manpower and working hours, and can standardize the dynamic performance test method of polyurethane foaming for seats, while accurately obtaining objective evaluation indicators that can reflect the dynamic performance of polyurethane foaming for seats. This method can comprehensively evaluate the advantages and disadvantages of the dynamic performance of polyurethane foaming for seats, and provide a theoretical basis and optimization direction for the subsequent design of seat vibration comfort.

[0035] The following describes a method for testing the performance of polyurethane foam and an apparatus for testing the performance of polyurethane foam provided in an embodiment of the present invention with reference to the accompanying drawings.

[0036] Figure 1 The present invention is a flowchart of a method for testing the performance of polyurethane foaming according to an embodiment of the present invention.

[0037] like Figure 1 As shown, the performance testing method of the polyurethane foaming according to the embodiment of the present invention may include the following steps:

[0038] S1, applying pressure to the test sample until the pressure value of the test sample reaches a preset pressure threshold, wherein the test sample is polyurethane foam, and the preset pressure threshold can be determined according to actual conditions.

[0039] S2, when it is determined that the stress relaxation of the test sample reaches an equilibrium state, applying a test vibration signal to the test sample to obtain a target pressure value and a target displacement value of the test sample under the test vibration signal.

[0040] S3, testing the performance of polyurethane foaming based on the target pressure value and the target displacement value.

[0041] Specifically, before the performance test, a certain amount of pressure needs to be applied to the test sample of the polyurethane foam material to make it reach the preset pressure threshold. This threshold is a reference point of the experiment and can be used to simulate the pressure applied to the polyurethane foam material when a person sits on a seat.

[0042] After applying pressure to the test sample, it is necessary to determine whether the stress relaxation of the test sample has reached a balanced state. Only when it is determined that the stress relaxation of the test sample has reached a balanced state, the test vibration signal is applied to the test sample. In other words, the stress relaxation of the test sample needs to reach a balanced state to ensure that the test sample is stable before the vibration test and exclude any transient effects. Therefore, when the stress relaxation of the test sample reaches a balanced state, a specific test vibration signal can be applied to the sample to obtain the target pressure value and target displacement value of the test sample under the test vibration signal. Among them, the target pressure value is the pressure exerted on the test sample under the current test vibration signal, and the target displacement value is the deformation amount of the test sample under the pressure. For example, the test vibration signal can be a sine wave, a random vibration, or a complex vibration signal simulating actual road conditions. Under the action of the vibration signal, the pressure value and displacement value of the sample within a specific time or vibration cycle are recorded. These values ​​are called target pressure values ​​and target displacement values, which are used to evaluate the performance of polyurethane foam materials under dynamic conditions.

[0043] After determining the target pressure value and the target displacement value, the performance of the polyurethane foam can be tested according to the target pressure value and the target displacement value. For example, by gradually increasing the pressure value and measuring the corresponding displacement value, a pressure value-displacement value curve can be drawn to evaluate the elastic modulus and yield strength of the material, or the polyurethane foam is kept at a certain pressure value for a certain period of time, and then the pressure is reduced, and the permanent amount of the displacement value is measured and recorded to evaluate the compression permanent deformation characteristics of the test sample, etc. In this way, the dynamic performance test method of polyurethane foam can be standardized, providing a basis for subsequent dynamic performance testing.

[0044] According to an embodiment of the present invention, the test vibration signal is a single-axis swept frequency excitation.

[0045] Further, according to an embodiment of the present invention, applying a test vibration signal to the test sample includes: applying a sine frequency sweep excitation with a preset frequency range and a preset acceleration to the test sample, wherein the preset frequency range and the preset acceleration can be determined according to actual conditions.

[0046] Specifically, uniaxial frequency sweep excitation means that a sine wave excitation signal with a frequency that varies with time can be applied to the test object in a single direction (for example, the vertical direction, corresponding to the force of simulating a person sitting down during seat testing). The starting and ending frequencies of the frequency sweep can be determined based on the actual working conditions of the seat and the frequency of human perception, and different vibration accelerations can be determined to cover the excitation range under conventional road test conditions. For example, the preset frequency range can be 1-40Hz, and the preset acceleration can be 0.2m / s 2 、0.4m / s 2 、0.6m / s 2 、0.8m / s 2 , 1.0m / s 2 , which defines the intensity or amplitude of vibration. Therefore, in the testing of polyurethane foam materials for seats, this method can simulate various vibration environments that seats may encounter in actual use, helping engineers understand the dynamic behavior of materials at different frequencies and amplitudes, so as to design more comfortable and better-performing seats.

[0047] According to one embodiment of the present invention, the performance of polyurethane foaming is tested based on target pressure values ​​and target displacement values, including: performing Fourier transform on the target pressure values ​​and target displacement values ​​to obtain frequency domain data; and testing the performance of polyurethane foaming based on the frequency domain data.

[0048] Specifically, when the performance of polyurethane foam is tested based on the target pressure value and the target displacement value, the reaction data of the polyurethane foam sample under specific pressure and displacement is collected. In order to realize the real-time monitoring of the dynamic response of the sample in the vibration test through high-precision sensors, the data is the data in the time domain. In order to analyze the performance of polyurethane foam more easily, the target pressure value and the target displacement value can be Fourier transformed to obtain frequency domain data. In addition, before Fourier transforming, some preprocessing can be performed on the time domain data, such as removing the DC component, noise filtering or applying a window function to reduce spectrum leakage, etc., and the data quality can be checked at all times. When necessary, the time domain signal can be intercepted to remove data with large errors. Therefore, the collected pressure and displacement time domain signals are subjected to fast Fourier transform (FFT) or other types of Fourier transform to obtain frequency domain data, so that the performance of polyurethane foam can be tested based on the frequency domain data. For example, the target pressure value and target displacement value collected in the time domain are converted to the frequency domain through Fourier transform to obtain the corresponding frequency response function, and the performance of the polyurethane foaming is determined according to the amplitude and phase of the frequency response function.

[0049] According to one embodiment of the present invention, the performance of polyurethane foam is tested based on frequency domain data, including: acquiring at least one of dynamic stiffness, dynamic damping, energy dissipation coefficient, vibration transfer coefficient and vibration comfort coefficient according to the frequency domain data; determining the performance of polyurethane foam according to at least one of dynamic stiffness, dynamic damping, energy dissipation coefficient, vibration transfer coefficient and vibration comfort coefficient.

[0050] Specifically, when testing the performance of polyurethane foaming according to frequency domain data, at least one of dynamic stiffness, dynamic damping, energy dissipation coefficient, vibration transmission coefficient and vibration comfort coefficient can be obtained according to the frequency domain data. For example, dynamic stiffness can be defined as the complex ratio of dynamic load force to dynamic displacement in the frequency domain. Dynamic stiffness can be obtained by formula Determine, where Z(ω) represents dynamic stiffness, which is a complex number, F(ω) is the dynamic load force, and X(ω) is the dynamic displacement. Dynamic damping is equivalent to the viscous damping coefficient that changes with frequency when the sample is subjected to external excitation. The higher the value in the resonance area and the lower the value in the vibration reduction area, the better the dynamic performance of the foaming. This value can be derived from the dynamic stiffness formula. For example, when a load is applied to the test sample and a vibration load is generated at the same time, the response of the sample can be expressed as: Among them, x and are the input displacement and velocity respectively, and F(t) is the force measured by the pressure head. After performing a tensile transformation, we can obtain: F(S) = CSX(S) + KX(S). Dividing both sides of the formula by the displacement X(S), we can obtain: From this, it can be seen that the dynamic damping is strongly correlated with the imaginary part of the dynamic stiffness, and further we can get: C = Z(ω)sinθ / 2πf, where f = ω / 2π, K is the stiffness coefficient and C is the dynamic damping.

[0051] The energy dissipation coefficient can be expressed as the energy consumed by the test sample during the vibration cycle. This parameter is used to evaluate the ability of foaming to absorb energy under dynamic conditions, such as through the formula ΔE=πCωX 2 It is represented by, where E is the energy dissipation coefficient, C is the dynamic damping, and X is the vibration amplitude. The vibration transfer coefficient is Under this vibration condition, the vibration transfer function of the system can be derived, which can be obtained by the formula Determine, where K is the energy storage stiffness, that is, the real part of the dynamic stiffness, C is the dynamic damping, m is the average mass, which is the ratio of the dynamic force to the gravitational acceleration g. This parameter can be used to evaluate the vibration attenuation ability of the foam under dynamic conditions. The lower the value, the better the vibration isolation performance of the foam.

[0052] The vibration comfort factor can be used to evaluate the vibration comfort of foaming under dynamic conditions. It can be expressed by the formula Determine, where S is the area enclosed by T and the horizontal axis frequency f in the vibration transfer coefficient curve within the frequency range of interest (2-40Hz), T max is the maximum vibration transfer coefficient in the frequency range of interest (2-40 Hz) (generally the vibration transfer coefficient at the resonant frequency), T 20 is the vibration transfer coefficient at a frequency of 20 Hz, R is the vibration comfort coefficient, and the larger the vibration comfort coefficient R is, the better the comprehensive vibration comfort brought by the foaming.

[0053] Therefore, the performance of polyurethane foam can be determined according to one or more evaluation indicators of dynamic stiffness, dynamic damping, energy consumption coefficient, vibration transmission coefficient and vibration comfort coefficient. For example, 9 polyurethane foam samples for seats are selected, and dynamic performance testing and evaluation are carried out according to the method proposed in the present invention. Before the test, the 9 foam samples are divided into two categories according to their physical properties: the first category is that except for the hardness, the other physical properties of the foam are the same; the second category is that except for the thickness, the other physical properties of the foam are the same, as shown in Table 1-2 below.

[0054] Table 1: Foam test specimens with different hardness

[0055] serial number Foaming properties 1 D65L155H60 2 D65L200H60 3 D65L240H60

[0056] Table 2: Foam test samples with different thicknesses

[0057] serial number Foaming properties 4 D65L155H50 5 D65L155H60 6 D65L155H70 7 D65L155H80 8 D65L155H90 9 D65L155H100

[0058] The dimensions of all the foam test samples mentioned above are 400mm×400mm. In the description of foam properties, D represents density, L represents hardness, and H represents thickness. For example, the foam property D65L155H60 means that the density of the foam sample is 65kg / m 3 , hardness is 155N, thickness is 60mm. For the purpose of cushion foam selection, refer to the 50% percentile human body weight in sitting position, set the pressure applied to the test sample to 500N, and the vibration excitation size to 0.4m / s 2 . According to the test method proposed in this invention, all foam samples are tested in a standardized manner, and then the dynamic performance evaluation is carried out. For example, the dynamic stiffness calculation curve is as follows Figure 2-3 shown. Figure 2 is the dynamic stiffness result of foam samples with different hardness, Figure 3 The dynamic stiffness results of foam samples with different thicknesses are shown below. From this, we can see that increasing the hardness of the foam sample or increasing the thickness of the foam sample can reduce the dynamic stiffness and improve the dynamic characteristics of the foam sample. The dynamic damping calculation curve is as follows Figure 4-5 shown. Figure 4 The dynamic damping results of foam samples with different hardness are shown in Figure 2. Figure 5 The dynamic damping results of foam samples with different thicknesses are shown in Table 1. Figure 4 and Figure 5 It can be seen that increasing the hardness or thickness of the foamed sample can reduce the dynamic damping in the vibration reduction area, making the dynamic characteristics of the foamed sample in the vibration reduction area better. The energy dissipation coefficient calculation curve is as follows Figure 6-7 shown. Figure 6 The energy dissipation coefficient results of foam samples with different hardness are as follows: Figure 7 The energy dissipation coefficient results of foam samples with different thicknesses are shown in Table 1. Figure 6 and Figure 7 It can be seen that the energy consumption coefficient of all foam samples in the low frequency band (frequency < 15Hz) is much greater than that in the high frequency band (frequency > 15Hz). Increasing the hardness of the foam sample or increasing the thickness of the foam sample can reduce the energy consumption in the low frequency band. The vibration transfer coefficient calculation curve is as follows Figure 8-9 shown. Figure 8 The vibration transmission coefficient results of foam samples with different hardness are shown in Figure 2. Fig. 9 The vibration transmission coefficient results of foam samples with different thicknesses are shown in Figure 2. Figure 8 and Fig. 9In general, increasing the hardness or thickness of the foamed sample can reduce the vibration transfer coefficient and improve the vibration isolation performance of the foamed sample. In addition, increasing the hardness or thickness of the foamed sample can also effectively improve the vibration comfort coefficient of the foamed sample, thereby improving the comprehensive vibration comfort of the foamed sample under dynamic conditions. From this, it can be seen that within a certain range of hardness or thickness, the comprehensive vibration comfort of the foamed sample under dynamic conditions can be improved by increasing the foaming hardness or increasing the foaming thickness, which provides a theoretical basis and optimization direction for the subsequent design of seat vibration comfort.

[0059] According to an embodiment of the present invention, determining that the stress relaxation of the test sample has reached a balanced state includes: determining that the stress relaxation of the test sample has reached a balanced state when the pressure value does not change within a preset time period. The preset time period can be determined according to actual conditions.

[0060] Specifically, stress relaxation reaching a state of equilibrium refers to the state at the end of a process in which the internal stress of a material gradually decreases over time until it stabilizes at a lower level under conditions of continuous fixed strain (or displacement). When determining whether the stress relaxation of a test sample has reached a state of equilibrium, first, a preset time period needs to be set. This time period should be long enough to ensure that the stress relaxation process of the test sample can be completed. The preset time period can be determined based on material properties, previous test experience, or experimental instructions. During the preset time period, the pressure value on the test sample is continuously monitored, and during the preset time period, it is observed whether the pressure value remains stable. If the pressure value fluctuates very little or remains essentially unchanged over a period of time, it indicates that the stress relaxation process has approached or reached equilibrium. At the end of the preset time period, the recorded pressure data is checked and its stability is evaluated. If the data shows that the pressure value has not changed significantly during the preset time period, it can be considered that the stress relaxation of the test sample has reached equilibrium, thereby obtaining data that accurately reflects the dynamic performance of polyurethane foam for seats.

[0061] According to one embodiment of the present invention, the performance test method of polyurethane foaming further includes: applying pressure to the test sample at a preset speed until the thickness of the test sample reaches a preset thickness, stopping the pressure application to obtain a debugging pressure value-debugging displacement value curve, and repeating the preset number of times until multiple debugging pressure value-debugging displacement value curves are obtained. The preset speed, preset thickness, and preset number of times can be determined according to actual conditions.

[0062] Further, according to an embodiment of the present invention, the polyurethane foaming performance test method further includes: when the error between the multiple debugging pressure-debugging displacement value curves is less than a preset error value, determining that the test requirements are met. The preset error value can be determined according to actual conditions.

[0063] Specifically, in order to obtain more accurate pressure and displacement values ​​of the test sample, a test calibration can be performed before the performance test. For example, the preset speed can be 20 mm / min, and the preset thickness can be 70% of the test thickness (70% of the original thickness of the test sample). The test pressure head can be controlled to apply pressure to the test sample at a preset speed of 20 mm / min until the thickness of the test sample reaches 70% of the test thickness. The pressure can be stopped. During the pressure application process, the pressure value and the corresponding displacement value are recorded in real time to form a debugging pressure value-debugging displacement value curve. In addition, in order to obtain reliable test results, it is necessary to repeat the above process of applying pressure and recording data multiple times. The preset number of times should be determined according to the test requirements and the needs of statistical analysis. For example, it can be repeated 3 times until multiple debugging pressure value-debugging displacement value curves are obtained.

[0064] After obtaining multiple debugging pressure value-debugging displacement value curves, the errors between the multiple debugging pressure-debugging displacement value curves can be judged. When the error between the multiple debugging pressure-debugging displacement value curves is less than the preset error value, for example, the preset error is 10%, that is, when the error between the multiple debugging pressure-debugging displacement value curves is less than 10%, it can be determined that the test requirements are met. If the error is large, the test equipment, test sample or test method can be adjusted.

[0065] Combine the following Fig.10 To describe the test method of the present invention.

[0066] As a specific example, the performance testing method of the polyurethane foam of the present invention may include the following steps:

[0067] S101, applying pressure to the test sample at a preset speed until the thickness of the test sample reaches a preset thickness and then stopping the pressure application to obtain a debugging pressure value-debugging displacement value curve, and repeating the preset number of times until multiple debugging pressure value-debugging displacement value curves are obtained.

[0068] S102: When the error between the plurality of debugging pressure-debugging displacement value curves is less than a preset error value, it is determined that the test requirement is met.

[0069] S103, applying pressure to the test sample until the pressure value of the test sample reaches a preset pressure threshold, wherein the test sample is polyurethane foam.

[0070] S104, determining whether the pressure value does not change within a preset time period. If yes, executing step S105; if no, continuing to execute step S104.

[0071] S105, applying a sinusoidal frequency sweep excitation within a preset frequency range and a preset acceleration to the test sample to obtain a target pressure value and a target displacement value of the test sample under a test vibration signal.

[0072] S106, performing Fourier transform on the target pressure value and the target displacement value to obtain frequency domain data.

[0073] S107, obtaining at least one of dynamic stiffness, dynamic damping, energy consumption coefficient, vibration transfer coefficient and vibration comfort coefficient according to the frequency domain data.

[0074] S108, determining the performance of the polyurethane foam according to at least one of dynamic stiffness, dynamic damping, energy dissipation coefficient, vibration transmission coefficient and vibration comfort coefficient.

[0075] In summary, according to the performance test method of polyurethane foaming of the embodiment of the present invention, pressure is applied to the test sample until the pressure value of the test sample reaches a preset pressure threshold, wherein the test sample is polyurethane foaming; when it is determined that the stress relaxation of the test sample has reached an equilibrium state, a test vibration signal is applied to the test sample to obtain the target pressure value and target displacement value of the test sample under the test vibration signal; the performance of the polyurethane foaming is tested based on the target pressure value and target displacement value. Therefore, this method can standardize the dynamic performance test method of polyurethane foaming and provide a basis for subsequent dynamic performance testing.

[0076] Corresponding to the above-mentioned embodiment, the present invention also proposes a performance testing device for polyurethane foaming.

[0077] like Fig.11 As shown, the polyurethane foam performance testing device 100 according to the embodiment of the present invention includes: a pressure head 110 , a signal applicator 120 and a controller 130 .

[0078] The controller 130 is used to control the pressure head 110 to apply pressure to the test sample 140 until the pressure value of the test sample reaches a preset pressure threshold, wherein the test sample 140 is polyurethane foam. When it is determined that the stress relaxation of the test sample 140 reaches an equilibrium state, the control signal applicator 120 applies a test vibration signal to the test sample 140 to obtain a target pressure value and a target displacement value of the test sample 140 under the test vibration signal. The performance of the polyurethane foam is tested based on the target pressure value and the target displacement value.

[0079] According to one embodiment of the present invention, Fig.12As shown, the performance testing equipment 100 for polyurethane foaming further includes: a displacement sensor 150 and a pressure sensor 160 arranged on the pressure head, wherein the pressure sensor 160 is used to obtain the pressure value applied by the pressure head 110 to the test sample 140; and the displacement sensor 150 is used to obtain the displacement value of the test sample 140 under the pressure value.

[0080] Specifically, in one embodiment of the present invention, considering that when a human body sits down, the pressure is mainly concentrated in the two ischial tuberosities of the human body, so the pressure head 110 is made according to the pressure distribution at the ischial tuberosities. The size of the test sample 140 can be 400mm×400mm, and the material is flexible polyurethane foam, and the physical parameters such as thickness, density and hardness can be selected and made. The test can be carried out on a universal vibration testing machine, the pressure head 110 is screwed to the testing machine, and the pressure sensor 160 and the displacement sensor 150 are arranged at the position of the pressure head respectively. After calibration, the sensors are connected to the data acquisition system in turn, and the test sample 140 is placed flat on the bottom plate of the universal testing machine. The universal testing machine can be used as a signal applicator 120 to apply a test vibration signal to the test sample 140, so that the target pressure value and target displacement value of the test sample 140 under the test vibration signal can be obtained in the data acquisition system, and the performance of the polyurethane foam is tested according to the target pressure value and target displacement value.

[0081] According to an embodiment of the present invention, the test vibration signal is a single-axis swept frequency excitation.

[0082] According to an embodiment of the present invention, the controller 130 applies a test vibration signal to the test sample 140 , specifically for applying a sinusoidal frequency sweep excitation with a preset frequency range and a preset acceleration to the test sample 140 .

[0083] According to one embodiment of the present invention, the controller 130 tests the performance of polyurethane foaming based on the target pressure value and the target displacement value, specifically for: performing Fourier transform on the target pressure value and the target displacement value to obtain frequency domain data; and testing the performance of polyurethane foaming based on the frequency domain data.

[0084] According to one embodiment of the present invention, the controller 130 tests the performance of polyurethane foaming based on frequency domain data, specifically for: obtaining at least one of dynamic stiffness, dynamic damping, energy dissipation coefficient, vibration transfer coefficient and vibration comfort coefficient according to the frequency domain data; determining the performance of polyurethane foaming according to at least one of dynamic stiffness, dynamic damping, energy dissipation coefficient, vibration transfer coefficient and vibration comfort coefficient.

[0085] According to an embodiment of the present invention, the controller 130 determines that the stress relaxation of the test sample 140 reaches a balanced state, specifically for: when the pressure value does not change within a preset time period, determining that the stress relaxation of the test sample 140 reaches a balanced state.

[0086] According to one embodiment of the present invention, the controller 130 is also used to: apply pressure to the test sample 140 at a preset speed until the thickness of the test sample 140 reaches a preset thickness and then stop applying pressure to obtain a debugging pressure value-debugging displacement value curve, and repeat the preset number of times until multiple debugging pressure value-debugging displacement value curves are obtained.

[0087] According to an embodiment of the present invention, the controller 130 is further configured to: determine that the test requirement is met when the error between the plurality of debugging pressure-debugging displacement value curves is less than a preset error value.

[0088] It should be noted that for details not disclosed in the performance testing equipment for polyurethane foaming in the embodiment of the present invention, please refer to the details disclosed in the performance testing method for polyurethane foaming in the embodiment of the present invention, and the details will not be repeated here.

[0089] According to the performance testing equipment for polyurethane foaming of the embodiment of the present invention, the controller is used to control the pressure head to apply pressure to the test sample until the pressure value of the test sample reaches a preset pressure threshold, wherein the test sample is polyurethane foaming, and when it is determined that the stress relaxation of the test sample has reached an equilibrium state, the signal applicator is controlled to apply a test vibration signal to the test sample to obtain the target pressure value and target displacement value of the test sample under the test vibration signal, and the performance of the polyurethane foaming is tested based on the target pressure value and the target displacement value. Therefore, the testing equipment can standardize the dynamic performance testing method of polyurethane foaming and provide a basis for subsequent dynamic performance testing.

[0090] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways if necessary, and then stored in a computer memory.

[0091] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0092] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0093] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying 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 the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0094] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0095] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A performance testing method for polyurethane foaming, characterized in that: The method comprises: Applying pressure to the test sample until the pressure value of the test sample reaches a preset pressure threshold, wherein the test sample is polyurethane foam; When it is determined that the stress relaxation of the test sample has reached an equilibrium state, applying a test vibration signal to the test sample to obtain a target pressure value and a target displacement value of the test sample under the test vibration signal; The performance of the polyurethane foam is tested based on the target pressure value and the target displacement value.

2. The performance testing method of polyurethane foaming according to claim 1, characterized in that: The test vibration signal is a single-axis swept frequency excitation.

3. The performance testing method of polyurethane foaming according to claim 2, characterized in that: Applying a test vibration signal to the test sample comprises: A sine frequency sweep excitation with a preset frequency range and a preset acceleration is applied to the test sample.

4. The performance testing method of polyurethane foaming according to claim 1, characterized in that: The performance of the polyurethane foam is tested based on the target pressure value and the target displacement value, including: Performing Fourier transform on the target pressure value and the target displacement value to obtain frequency domain data; The performance of the polyurethane foam is tested based on the frequency domain data.

5. The performance testing method of polyurethane foaming according to claim 4, characterized in that: The performance of the polyurethane foam is tested based on the frequency domain data, including: Acquire at least one of dynamic stiffness, dynamic damping, energy dissipation coefficient, vibration transmission coefficient and vibration comfort coefficient according to the frequency domain data; The performance of the polyurethane foam is determined according to at least one of the dynamic stiffness, the dynamic damping, the energy dissipation coefficient, the vibration transmission coefficient, and the vibration comfort coefficient.

6. The performance testing method of polyurethane foaming according to claim 1, characterized in that: Determining that the stress relaxation of the test sample reaches an equilibrium state includes: When the pressure value does not change within a preset time period, it is determined that the stress relaxation of the test sample has reached an equilibrium state.

7. The performance testing method of polyurethane foaming according to claim 1, characterized in that: The method further comprises: Apply pressure to the test sample at a preset speed until the thickness of the test sample reaches a preset thickness, then stop applying pressure to obtain a debugging pressure value-debugging displacement value curve, and repeat the process for a preset number of times until multiple debugging pressure value-debugging displacement value curves are obtained.

8. The performance testing method of polyurethane foaming according to claim 7, characterized in that: The method further comprises: When the error between the plurality of debugging pressure-debugging displacement value curves is less than a preset error value, it is determined that the test requirement is met.

9. A performance testing device for polyurethane foaming, characterized in that: The device comprises: a pressure head, a signal applicator and a controller, wherein the controller is used to: Controlling the pressure head to apply pressure to the test sample until the pressure value of the test sample reaches a preset pressure threshold, wherein the test sample is polyurethane foam; When it is determined that the stress relaxation of the test sample has reached an equilibrium state, controlling the signal applicator to apply a test vibration signal to the test sample to obtain a target pressure value and a target displacement value of the test sample under the test vibration signal; The performance of the polyurethane foam is tested based on the target pressure value and the target displacement value.

10. The performance testing equipment for polyurethane foaming according to claim 9, characterized in that: Also includes: A displacement sensor and a pressure sensor are arranged on the pressure head, wherein: The pressure sensor is used to obtain the pressure value of the pressure applied by the pressure head to the test sample; The displacement sensor is used to obtain the displacement value of the test sample under the pressure value.

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