Method and device for testing vertical impact of all-carbon seat of airplane

Abstract

The invention relates to the technical field of composite material testing, in particular to a vertical impact testing method and device for an airplane all-carbon seat, and the method comprises the steps: carrying out a vertical impact test on an all-carbon fiber sample; determining whether the impact load can be used for the vertical impact test of the full-carbon seat of the target aircraft according to the failure evaluation value; performing a multi-stage vertical impact test on the target aircraft all-carbon seat sample, obtaining strain rates of a plurality of test points of a backrest of the target aircraft all-carbon seat, and obtaining a strain characterization value; when it is judged that the impact of the target aircraft all-carbon seat sample does not meet the preset standard according to the strain characterization value, whether the impact of the target aircraft all-carbon seat sample meets the preset standard or not is judged secondarily according to the strain offset characteristic value; and according to the residual vibration evaluation value of the target aircraft all-carbon seat sample, determining the reason that the impact of the target aircraft all-carbon seat sample does not meet the preset standard, thereby improving the impact test precision.

Description

Technical Field

[0001] The present invention relates to the technical field of composite material testing, and particularly to a vertical impact testing method and testing device for an all-carbon aircraft seat. Background Art

[0002] As a core component for the safety of aircraft occupants, the structural strength and impact resistance of an aircraft seat are directly related to the survival rate of occupants in emergency situations. Especially when an aircraft makes an emergency landing or encounters turbulence, an all-carbon seat needs to withstand severe vertical impact loads.

[0003] A seat is a safety component in transportation means such as automobiles, high-speed rails, and aircraft, and the contribution it can make to the lightweighting of the whole vehicle cannot be ignored.

[0004] The lightweighting and high strength of aircraft seats are core requirements for improving aviation safety and energy efficiency. Although traditional metal materials such as aluminum alloys have good ductility, their density is relatively high, making it difficult to meet the weight reduction requirements of modern aircraft. All-carbon fiber composite materials, with their high specific strength (strength / density) and customizable ply design, have become the preferred materials for the structural upgrade of aircraft seats. However, their anisotropy and delamination sensitivity need to be strictly verified through impact testing methods to produce safer all-carbon aircraft seats.

[0005] Chinese Patent Publication No.: CN102564876A, discloses a vertical impact testing device and testing method for an all-carbon seat. The testing device includes a test bench, a mounting bracket, an impact component, and a lifting mechanism, where: the test bench includes a base and a support fixed on the base, and the support bears the test seat; the mounting bracket includes left and right columns and a cross beam erected at the top ends of the left and right columns; the left and right columns are fixed on the base; the impact component is lifted by the lifting mechanism to a preset suspension height in the first state and freely released in the second state to impact the test part of the test seat. The testing method repeatedly lifts the impact component to the preset height and then allows it to freely fall to impact the test part of the test seat. If the test seat is deformed or broken within the preset number of impacts, it is determined to pass the test; otherwise, it is determined not to pass the test. In the present invention, the impact component freely falls from the suspended state, thereby applying a vertical impact load to the part of the seat to be tested. After repeating the test multiple times, the vertical strength of the seat can be tested.

[0006] It can be seen that in the above technical solution, the anisotropic characteristics of carbon fiber composite materials are not considered, and a general specimen is directly used for impact testing without simulating the actual ply structure at the connection between the seat back and the seat cushion. Only whether it is broken is used as the passing standard, lacking the analysis of strain rate and residual vibration characteristics, resulting in the inability to detect internal damage or structural looseness, and thus leading to the problem of low accuracy of impact testing. Summary of the Invention

[0007] To this end, the present invention provides a vertical impact test method and test device for an aircraft all-carbon seat, so as to overcome the problems in the prior art that the anisotropic characteristics of carbon fiber composites are not considered, a general specimen is directly used for impact testing, the actual ply structure at the connection between the seat back and the seat cushion is not simulated, and only whether it breaks is used as the passing standard, lacking the analysis of strain rate and residual vibration characteristics, resulting in the inability to detect internal damage or structural looseness, and thus the low accuracy of the impact test.

[0008] To achieve the above object, on the one hand, the present invention provides a vertical impact test method for an aircraft all-carbon seat, including: Conduct a vertical impact test on the all-carbon fiber specimen, record the impact load and obtain the delamination area of the all-carbon fiber specimen after being subjected to the impact load, and obtain the failure evaluation value; Determine whether the impact load can be used for the vertical impact test of the target aircraft all-carbon seat according to the failure evaluation value; Conduct a multi-stage vertical impact test on the target aircraft all-carbon seat specimen, obtain the strain rates of several test points on the backrest of the target aircraft all-carbon seat, and obtain the strain characterization value, wherein the ultimate impact load in the multi-stage vertical impact is the impact load that can be used for the vertical impact test of the target aircraft all-carbon seat; When it is determined according to the strain characterization value that the impact of the target aircraft all-carbon seat specimen does not meet the preset standard, obtain the average strain rate to obtain the strain offset characteristic value and the vibration duration of the target aircraft all-carbon seat specimen after impact to obtain the residual vibration evaluation value; When it is determined according to the strain characterization value that the impact of the target aircraft all-carbon seat specimen does not meet the preset standard, re-determine whether the impact of the target aircraft all-carbon seat specimen meets the preset standard according to the strain offset characteristic value, or determine the reason why the impact of the target aircraft all-carbon seat specimen does not meet the preset standard according to the residual vibration evaluation value of the target aircraft all-carbon seat specimen, wherein the reasons include structural looseness of the target aircraft all-carbon seat specimen and internal damage of the all-carbon material of the target aircraft all-carbon seat specimen.

[0009] Further, the all-carbon fiber specimen is a rectangular specimen with a preset thickness, wherein the ply angle, number of layers and thickness of the all-carbon fiber specimen are respectively the same as the ply angle, number of layers and thickness at the connection between the backrest and the seat cushion of the target aircraft all-carbon seat; the target aircraft all-carbon seat specimen simulates the structure of the target aircraft all-carbon seat through a hot pressing forming process.

[0010] Further, the process of the multi-stage vertical impact includes: The transient impact stage, which applies a half-sine pulse load to several test points evenly distributed on the backrest of the target aircraft all-carbon seat specimen with a preset acceleration and a first preset duration; During the continuous loading stage, an ultimate impact load that maintains for a second preset duration is applied after the transient impact.

[0011] Furthermore, it is determined whether the impact load can be used for the target vertical impact test according to the failure evaluation value, where if the failure evaluation value is less than the preset failure evaluation value, it is determined that the impact load can be used for the target vertical impact test; if the failure evaluation value is greater than or equal to the preset failure evaluation value, it is determined that the impact load cannot be used for the target vertical impact test; The failure evaluation value is the ratio between the delamination area of the all-carbon fiber specimen and the total area of the all-carbon fiber specimen.

[0012] Furthermore, the process of determining that the impact of the target aircraft all-carbon seat specimen does not meet the preset standard according to the strain characterization value includes: Comparing the strain characterization value with a first preset strain characterization value and a second preset strain characterization value respectively; If the strain characterization value is greater than or equal to the first preset strain characterization value and less than the second preset strain characterization value, it is determined that the impact of the target aircraft all-carbon seat specimen does not meet the preset standard, and the remanufactured target aircraft all-carbon seat specimen is used to re-determine whether the impact of the target aircraft all-carbon seat specimen meets the preset standard according to the strain offset characteristic value; If the strain characterization value is greater than or equal to the second preset strain characterization value, it is determined that the impact of the target aircraft all-carbon seat specimen does not meet the preset standard, and the reason why the impact of the target aircraft all-carbon seat specimen does not meet the preset standard is determined according to the residual vibration evaluation value of the target aircraft all-carbon seat specimen; The strain characterization value is the ratio between the average strain rate and the preset strain rate.

[0013] Furthermore, it is re-determined whether the impact of the target aircraft all-carbon seat specimen meets the preset standard according to the strain offset characteristic value, where if the strain offset characteristic value is less than the preset strain offset characteristic value, it is determined that the impact of the target aircraft all-carbon seat specimen meets the preset standard; if the strain offset characteristic value is greater than or equal to the preset strain offset characteristic value, it is determined that the impact of the target aircraft all-carbon seat specimen does not meet the preset standard, and the ultimate impact load is reduced according to the difference between the strain offset characteristic value and the preset strain offset characteristic value; The strain offset characteristic value is the ratio between the number of measurement points where the strain rate exceeds the preset strain rate and the total number of measurement points.

[0014] Further, several load reduction methods are provided for reducing the limit impact load, and each reduction method has a different reduction amplitude for the limit impact load.

[0015] Further, according to the residual vibration evaluation value of the target aircraft all-carbon seat sample, the reason why the impact of the target aircraft all-carbon seat sample does not meet the preset standard is determined, where if the residual vibration evaluation value is less than the preset residual vibration evaluation value, it is determined that the reason why the impact of the target aircraft all-carbon seat sample does not meet the preset standard is that the structure of the target aircraft all-carbon seat sample is loose; if the residual vibration evaluation value is greater than or equal to the preset residual vibration evaluation value, it is determined that the reason why the impact of the target aircraft all-carbon seat sample does not meet the preset standard is internal damage to the all-carbon material of the target aircraft all-carbon seat sample.

[0016] Further, the residual vibration evaluation value is the ratio between the vibration duration of the target aircraft all-carbon seat sample after impact and the preset duration.

[0017] On the other hand, the present invention provides a test device applicable to the vertical impact test method of an aircraft all-carbon seat, including: a base, an adjustable fixture arranged above the base for fixing a full-carbon fiber sample or a target aircraft all-carbon seat sample, a mounting frame connected to the base through a first column and a second column of the mounting frame, and a pendulum connected to the top rod of the mounting frame through a pendulum shaft; A data acquisition module, including a load acquisition unit for obtaining an impact load, an area acquisition unit for obtaining the delamination area of the full-carbon fiber sample, a strain rate acquisition unit for obtaining the backrest strain rate, and a duration acquisition unit for obtaining the target aircraft all-carbon seat sample; A control module, which is connected to the data acquisition module, and is used to determine whether the impact load can be used for the vertical impact test of the target aircraft all-carbon seat according to the failure evaluation value; and is used to determine whether the impact of the target aircraft all-carbon seat sample meets the preset standard according to the strain characterization value.

[0018] Compared with the prior art, the beneficial effects of the present invention are that the present invention significantly improves the accuracy of the impact test by constructing a material-level equivalent test system. A full-carbon fiber rectangular sample with the same ply angle, number of layers, and thickness as the connection between the backrest and the seat cushion of the target aircraft all-carbon seat is used to accurately reproduce the anisotropic characteristics of the carbon fiber composite material, avoiding test deviations caused by differences between the general sample and the actual structure, thereby providing a reliable material failure benchmark for impact load calibration.

[0019] Furthermore, in the present invention, a semi - sine pulse load is applied during the transient shock stage to simulate the initial shock of an emergency landing, and the ultimate shock load is maintained during the continuous loading stage to reproduce the subsequent overload, completely covering the dynamic response process of the all - carbon seat under vertical shock, thereby solving the defect that the traditional single - pulse test cannot restore the action of composite loads.

[0020] Furthermore, the present invention quantifies the degree of dynamic overload by introducing the ratio of the average strain rate to a preset threshold, i.e., the strain characterization value, and combines the ratio of the vibration duration to a preset duration, i.e., the residual vibration evaluation value, to analyze the structural integrity. It can not only identify the risk of local overload but also distinguish between structural looseness and internal material damage, thereby breaking through the limitation of only using fracture deformation as the standard.

[0021] Furthermore, the present invention uses the ratio of the delaminated area of the all - carbon fiber specimen to the total area as the failure evaluation value, establishes the correlation between material failure and structural testing, ensures the matching of the ultimate shock load and the load - bearing capacity of the target all - carbon seat, avoids over - testing or under - testing, and thus improves the credibility of the test results.

[0022] Furthermore, based on the ratio of the average strain rate to a preset value and the strain offset characteristic value, precise positioning of the local overload area and dynamic adjustment of the load are achieved, avoiding the roughness of the overall strain evaluation in the traditional method, and thus improving the test accuracy.

[0023] Furthermore, the present invention is provided with several load - reducing methods for reducing the ultimate shock load, and each load - reducing method has a different reduction amplitude for the ultimate shock load, thereby achieving precise control of the reduction amplitude of the ultimate shock load. Description of the Drawings

[0024] Figure 1 is a flow chart of the vertical shock test method for the all - carbon seat of the aircraft in the embodiment of the present invention; Figure 2 is a flow chart of determining whether the shock load can be used for the target vertical shock test in the embodiment of the present invention; Figure 3 is a flow chart of determining whether the shock test method meets the preset standard according to the strain characterization value in the embodiment of the present invention; Figure 4 is a flow chart of determining the reason why the shock test method does not meet the preset standard in the embodiment of the present invention; Figure 5 is a structural schematic diagram of the vertical shock test device for the all - carbon seat of the aircraft in the embodiment of the present invention; In the figure, 1. base; 2. adjustable fixture; 3. first column; 4. second column; 5. ejector rod; 6. swing shaft; 7. pendulum hammer. Detailed Embodiment

[0025] To make the objectives and advantages of the present invention more clearly understood, the present invention will be further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present invention and do not limit the protection scope of the present invention.

[0027] Please refer to Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 and Figure 5 as shown, which are respectively the flowcharts of the vertical impact test method for the all-carbon seat of an aircraft in the embodiments of the present invention; the flowchart of determining whether the impact load can be used for the target vertical impact test of the all-carbon seat of an aircraft in the embodiments of the present invention; the flowchart of determining whether the impact test method meets the preset standard according to the strain characterization value in the embodiments of the present invention; the flowchart of determining the reason why the impact test method does not meet the preset standard in the embodiments of the present invention; the structural schematic diagram of the vertical impact test device for the all-carbon seat of an aircraft in the embodiments of the present invention.

[0028] On the one hand, an embodiment of the present invention provides a vertical impact test method for an all-carbon seat of an aircraft, including: Step S1: Conduct a vertical impact test on the all-carbon fiber specimen, record the impact load, obtain the delamination area of the all-carbon fiber specimen after being subjected to the impact load, and calculate the failure evaluation value. Step S2: Determine whether the impact load can be used for the target vertical impact test of the all-carbon seat of an aircraft according to the failure evaluation value. Step S3: Conduct a multi-stage vertical impact test on the target all-carbon seat specimen of the aircraft, obtain the strain rates of several test points on the backrest of the target all-carbon seat of the aircraft, and calculate the strain characterization value, where the ultimate impact load in the multi-stage vertical impact is the impact load that can be used for the target vertical impact test of the all-carbon seat of the aircraft. Step S4: When it is determined that the impact on the target all-carbon seat specimen of the aircraft does not meet the preset standard according to the strain characterization value, obtain the average strain rate to calculate the strain deviation characteristic value and obtain the residual vibration evaluation value of the vibration duration of the target all-carbon seat specimen of the aircraft after the impact. Step S5: When it is determined that the impact on the target all-carbon seat specimen of the aircraft does not meet the preset standard according to the strain characterization value, re-determine whether the impact on the target all-carbon seat specimen of the aircraft meets the preset standard according to the strain deviation characteristic value, or determine the reason why the impact on the target all-carbon seat specimen of the aircraft does not meet the preset standard according to the residual vibration evaluation value of the target all-carbon seat specimen of the aircraft, where the reasons include the structural looseness of the target all-carbon seat specimen of the aircraft and the internal damage of the all-carbon material of the target all-carbon seat specimen of the aircraft.

[0029] In this embodiment, the strain rates of a number of test points on the backrest of the target aircraft's all-carbon seat in step S3 are obtained by a number of fiber Bragg grating sensors disposed inside the backrest and corresponding one-to-one to the test points with a sampling rate of 100 kHz.

[0030] Specifically, the all-carbon fiber specimen is a rectangular specimen with a preset length of 300 mm and a preset width of 150 mm. Among them, the ply angle, number of plies, and thickness of the all-carbon fiber specimen are respectively the same as those of the connection between the backrest and the seat cushion of the target aircraft's all-carbon seat; the target aircraft all-carbon seat specimen simulates the structure of the target aircraft all-carbon seat through a hot pressing forming process.

[0031] Specifically, in step S1, an impact test is performed on the all-carbon fiber specimen using a pendulum type vertical impact testing machine, and a load sensor is used to record the impact load. Among them, the load sensor is embedded inside the pendulum. The load sensor can be a piezoelectric sensor or a strain gauge sensor, and no specific limitation is made, as long as the impact load recording requirement is met.

[0032] Specifically, the process of the multi-stage vertical impact includes: A transient impact stage, which applies a half-sine pulse load to a number of test points evenly distributed on the backrest of the target aircraft all-carbon seat specimen with a preset acceleration of 50 g and a first preset duration of 10 ms; A continuous loading stage, which applies a limit impact load that maintains for a second preset duration of 100 ms after the transient impact.

[0033] Specifically, it is determined whether the impact load can be used for the target vertical impact test according to the failure evaluation value. Among them, If the failure evaluation value is less than the preset failure evaluation value of 7.5%, it is determined that the impact load can be used for the target vertical impact test; If the failure evaluation value is greater than or equal to the preset failure evaluation value, it is determined that the impact load cannot be used for the target vertical impact test; The failure evaluation value is the ratio between the delaminated area of the all-carbon fiber specimen and the total area of the all-carbon fiber specimen. Among them, ultrasonic CT scanning is used to detect the delamination damage generated inside the carbon fiber composite material due to impact to obtain the delaminated area. The delaminated area refers to the two-dimensional projected area of the damage area formed by the delamination of the interlayer interface, that is, delamination, after the composite laminate is subjected to an impact load.

[0034] The failure evaluation value quantifies the severity of delamination damage, and the damage tolerance of the all-carbon fiber composite material under the impact load is judged through the failure evaluation value.

[0035] In this embodiment, the preset failure evaluation value is selected as 7.5%. However, the above value is not limited to this, and those skilled in the art can also adjust this value according to actual needs.

[0036] Specifically, the process of determining whether the impact of the target aircraft all-carbon seat sample meets the preset standard according to the strain characterization value includes: Comparing the strain characterization value with a first preset strain characterization value of 0.98 and a second preset strain characterization value of 1.35 respectively; If the strain characterization value is less than the first preset strain characterization value, it is determined that the impact of the target aircraft all-carbon seat sample meets the preset standard; If the strain characterization value is greater than or equal to the first preset strain characterization value and less than the second preset strain characterization value, it is determined that the impact of the target aircraft all-carbon seat sample does not meet the preset standard, and the re-prepared target aircraft all-carbon seat sample is used to re-determine whether the impact of the target aircraft all-carbon seat sample meets the preset standard according to the strain offset characteristic value; If the strain characterization value is greater than or equal to the second preset strain characterization value, it is determined that the impact of the target aircraft all-carbon seat sample does not meet the preset standard, and the reason why the impact of the target aircraft all-carbon seat sample does not meet the preset standard is determined according to the residual vibration evaluation value of the target aircraft all-carbon seat sample; The strain characterization value is the ratio between the average strain rate and a preset strain rate of 1200 με / s, where the average strain rate is the average of the strain rates of several test points evenly distributed on the backrest of the target aircraft all-carbon seat sample.

[0037] In this embodiment, the value range of the first preset strain characterization value is (0.75, 1.00), and the value range of the second preset strain characterization value is (1.15, 1.55). Preferably, the first preset strain characterization value is selected as 0.98, and the second preset strain characterization value is selected as 1.35.

[0038] Specifically, according to the strain offset characteristic value, it is re-determined whether the impact of the target aircraft all-carbon seat sample meets the preset standard, where If the strain offset characteristic value is less than a preset strain offset characteristic value of 0.25, it is determined that the impact of the target aircraft all-carbon seat sample meets the preset standard; If the strain offset characteristic value is greater than or equal to the preset strain offset characteristic value, it is determined that the impact of the target aircraft all-carbon seat sample does not meet the preset standard, and the ultimate impact load is reduced according to the difference between the strain offset characteristic value and the preset strain offset characteristic value; The strain offset characteristic value is the ratio between the number of measurement points where the strain rate exceeds the preset strain rate of 1200 με / s and the total number of measurement points.

[0039] In this embodiment, the preset strain offset characteristic value is taken as 0.25. The value of the preset strain offset characteristic value is adjusted by those skilled in the art according to the requirements of the detection and evaluation accuracy of the impact resistance performance of the all-carbon seat. The higher the requirement for the detection and evaluation accuracy, the smaller the value of the preset strain offset characteristic value. Preferably, the value range of the preset strain offset characteristic value can be (0.10, 0.40).

[0040] Specifically, several load reduction methods are set for the reduction of the ultimate impact load, among which, if the strain offset difference is less than the first preset strain offset difference of 0.08, the first load adjustment coefficient of 0.98 is used to reduce the ultimate impact load to the corresponding value; if the strain offset difference is greater than or equal to the first preset strain offset difference and less than the second preset strain offset difference of 0.19, the second load adjustment coefficient of 0.96 is used to reduce the ultimate impact load to the corresponding value; if the strain offset difference is greater than or equal to the second preset strain offset difference, the third load adjustment coefficient of 0.94 is used to reduce the ultimate impact load to the corresponding value; The strain offset difference is the difference between the strain offset characteristic value and the preset strain offset characteristic value.

[0041] Specifically, according to the residual vibration evaluation value of the all-carbon seat sample of the target aircraft, the reason why the impact of the all-carbon seat sample of the target aircraft does not meet the preset standard is determined, among which, if the residual vibration evaluation value is less than the preset residual vibration evaluation value of 0.33, it is determined that the reason why the impact of the all-carbon seat sample of the target aircraft does not meet the preset standard is that the structure of the all-carbon seat sample of the target aircraft is loose; if the residual vibration evaluation value is greater than or equal to the preset residual vibration evaluation value, it is determined that the reason why the impact of the all-carbon seat sample of the target aircraft does not meet the preset standard is the internal damage of the all-carbon material of the all-carbon seat sample of the target aircraft.

[0042] Specifically, the residual vibration evaluation value is the ratio of the vibration duration of the all-carbon seat sample of the target aircraft after impact to the preset duration of 5S.

[0043] In this embodiment, the vibration duration of the all-carbon seat sample of the target aircraft after impact is obtained by an acceleration sensor arranged at the center point of the backrest.

[0044] In this embodiment, the preset residual vibration evaluation value is selected as 0.33, but the above value is not limited to this, and those skilled in the art can also adjust this value according to actual needs.

[0045] On the other hand, the present invention provides a testing device applicable to a vertical impact testing method for an all-carbon aircraft seat, comprising: a base 1, an adjustable fixture 2 disposed above the base 1 for fixing an all-carbon fiber specimen or a target aircraft all-carbon seat specimen, a mounting frame connected to the base 1 through a first column 3 and a second column 4 of the mounting frame, and a pendulum 7 connected to a top rod 5 of the mounting frame through a pendulum shaft 6; A data acquisition module, including a load acquisition unit for acquiring an impact load, an area acquisition unit for acquiring the delamination area of the all-carbon fiber specimen, a strain rate acquisition unit for acquiring the backrest strain rate of the target aircraft all-carbon seat specimen, and a duration acquisition unit for acquiring the duration of the target aircraft all-carbon seat specimen; A control module, which is connected to the data acquisition module, and is used for determining whether the impact load can be used for the vertical impact testing of the target aircraft all-carbon seat according to a failure evaluation value; and for determining whether the impact on the target aircraft all-carbon seat specimen meets a preset standard according to a strain characterization value.

[0046] Specifically, the clamping surface of the adjustable fixture is covered with a silica gel pad, which is used to avoid pinching the specimen.

[0047] So far, the technical solution of the present invention has been described in conjunction with the preferred embodiments shown in the drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A vertical impact test method for an aircraft full carbon seat, characterized in that: include: Performing a vertical impact test on the all-carbon fiber sample, recording the impact load and obtaining the delamination area of ​​the all-carbon fiber sample after the impact load, and obtaining a failure evaluation value; Determining, according to the failure evaluation value, whether the impact load can be used for a vertical impact test of a full carbon seat of a target aircraft; Perform a multi-stage vertical impact test on a target aircraft full-carbon seat sample, obtain the strain rate of several test points on the backrest of the target aircraft full-carbon seat, and obtain a strain characterization value, wherein the limit impact load in the multi-stage vertical impact test is the impact load that can be used for the vertical impact test of the target aircraft full-carbon seat; When it is determined according to the strain characterization value that the impact of the target aircraft full carbon seat specimen does not meet the preset standard, the average strain rate is obtained to obtain the strain offset characteristic value and the vibration duration of the target aircraft full carbon seat specimen after the impact is obtained to obtain the residual vibration evaluation value; When it is determined that the impact of the target aircraft all-carbon seat specimen does not meet the preset standard based on the strain characterization value, a second determination is made as to whether the impact of the target aircraft all-carbon seat specimen meets the preset standard based on the strain offset characteristic value, or the reason why the impact of the target aircraft all-carbon seat specimen does not meet the preset standard is determined based on the residual vibration evaluation value of the target aircraft all-carbon seat specimen, wherein the reason includes structural looseness of the target aircraft all-carbon seat specimen and internal damage to the all-carbon material of the target aircraft all-carbon seat specimen.

2. The vertical impact test method for an aircraft full carbon seat according to claim 1, characterized in that: The all-carbon fiber sample is a rectangular sample with a preset thickness, wherein the ply angle, number of layers and thickness of the all-carbon fiber sample are respectively the same as the ply angle, number of layers and thickness at the connection between the backrest and the seat cushion of the target aircraft all-carbon seat; the target aircraft all-carbon seat sample simulates the structure of the target aircraft all-carbon seat through a hot pressing molding process.

3. The vertical impact test method for an aircraft full carbon seat according to claim 2, characterized in that: The multi-stage vertical impact process includes: A transient impact stage, in which a half-sine pulse load is applied to a plurality of test points evenly distributed on the back of the full carbon seat specimen of the target aircraft at a preset acceleration and a first preset duration; The continuous loading stage applies an extreme impact load for a second preset time period after the transient impact.

4. The vertical impact test method for an aircraft full carbon seat according to claim 3, characterized in that: According to the failure evaluation value, it is determined whether the impact load can be used for the target vertical impact test, wherein: If the failure evaluation value is less than the preset failure evaluation value, it is determined that the impact load can be used for the target vertical impact test; If the failure evaluation value is greater than or equal to the preset failure evaluation value, it is determined that the impact load cannot be used for the target vertical impact test; The failure evaluation value is a ratio between the delamination area of ​​the all-carbon fiber sample and the total area of ​​the all-carbon fiber sample.

5. The vertical impact test method for an aircraft full carbon seat according to claim 4, characterized in that: The process of determining, according to the strain characterization value, that the impact of the full carbon seat specimen of the target aircraft does not meet the preset standard comprises: Comparing the strain characterization value with a first preset strain characterization value and a second preset strain characterization value respectively; If the strain characterization value is greater than or equal to the first preset strain characterization value and less than the second preset strain characterization value, it is determined that the impact of the target aircraft full carbon seat specimen does not meet the preset standard, and the re-made target aircraft full carbon seat specimen is re-determined according to the strain offset characteristic value whether the impact method of the target aircraft full carbon seat specimen meets the preset standard; If the strain characterization value is greater than or equal to the second preset strain characterization value, it is determined that the impact of the target aircraft full carbon seat sample does not meet the preset standard and the reason why the impact of the target aircraft full carbon seat sample does not meet the preset standard is determined according to the residual vibration evaluation value of the target aircraft full carbon seat sample; The strain characterization value is the ratio between the average strain rate and the preset strain rate.

6. The vertical impact test method for an aircraft full carbon seat according to claim 5, characterized in that: A secondary determination is made based on the strain offset characteristic value whether the impact of the target aircraft full carbon seat specimen meets the preset standard, wherein: If the strain offset characteristic value is less than a preset strain offset characteristic value, it is determined that the impact of the target aircraft full carbon seat specimen meets the preset standard; If the strain offset characteristic value is greater than or equal to the preset strain offset characteristic value, it is determined that the impact of the target aircraft full carbon seat specimen does not meet the preset standard, and the limit impact load is reduced according to the difference between the strain offset characteristic value and the preset strain offset characteristic value; The strain offset characteristic value is a ratio between the number of measurement points whose strain rate exceeds the preset strain rate and the total number of measurement points.

7. The vertical impact test method for an aircraft full carbon seat according to claim 6, characterized in that: Several load reduction methods are provided for reducing the ultimate impact load, and each reduction method has a different reduction range for the ultimate impact load.

8. The vertical impact test method for an aircraft full carbon seat according to claim 7, characterized in that: The reason why the impact of the full carbon seat sample of the target aircraft does not meet the preset standard is determined according to the residual vibration evaluation value of the full carbon seat sample of the target aircraft, wherein: If the residual vibration evaluation value is less than the preset residual vibration evaluation value, it is determined that the reason why the impact of the target aircraft full carbon seat sample does not meet the preset standard is that the structure of the target aircraft full carbon seat sample is loose; If the residual vibration evaluation value is greater than or equal to the preset residual vibration evaluation value, it is determined that the reason why the impact of the target aircraft full-carbon seat sample does not meet the preset standard is that the internal damage of the full-carbon material of the target aircraft full-carbon seat sample is caused.

9. The vertical impact test method for an aircraft full carbon seat according to claim 8, characterized in that: The residual vibration evaluation value is the ratio between the vibration duration of the target aircraft full carbon seat specimen after impact and the preset duration.

10. A test device suitable for the vertical impact test method of an aircraft full carbon seat according to any one of claims 1 to 9, characterized in that: include: A base, an adjustable fixture disposed above the base for fixing a full carbon fiber sample or a full carbon seat sample of a target aircraft, a mounting frame connected to the base via a first column of the mounting frame and a second column of the mounting frame, and a pendulum connected to a top rod of the mounting frame via a pendulum shaft; A data acquisition module, including a load acquisition unit for acquiring an impact load, an area acquisition unit for acquiring a delamination area of ​​the full carbon fiber sample, a strain rate acquisition unit for acquiring a back strain rate of the full carbon seat sample of the target aircraft, and a duration acquisition unit for acquiring the full carbon seat sample of the target aircraft; A control module is connected to the data acquisition module, and is used to determine whether the impact load can be used for the vertical impact test of the full carbon seat of the target aircraft according to the failure evaluation value; and to determine whether the impact of the full carbon seat sample of the target aircraft meets the preset standard according to the strain characterization value.

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