Multi-factor evaluation method for influence of environmental total factors on dynamic conductance characteristics of carbon fiber composite material

Abstract

This invention provides a multi-factor evaluation method for the influence of all environmental factors on the dynamic conductivity properties of carbon fiber composites. It obtains the influence laws of environmental factors such as temperature, humidity, and ultraviolet irradiation on the pulse dynamic conductivity properties of carbon fiber composites. A multi-factor evaluation model for the environmental factors affecting the dynamic conductivity properties of carbon fiber composites is established, obtaining mathematical expressions and corresponding influencing factors between the pulse dynamic conductivity properties of carbon fiber composites and environmental factors such as temperature, humidity, and ultraviolet irradiation intensity. This provides a theoretical basis for the study of lightning damage characteristics of carbon fiber composite laminates and the design of lightning protection structures.

Description

Technical Field

[0001] This invention belongs to the field of electrical technology and relates to a method for evaluating the electrical properties of carbon fiber composite materials, particularly a multi-factor evaluation method for the influence of all environmental factors on the dynamic conductivity properties of carbon fiber composite materials. Background Technology

[0002] Carbon fiber composites, possessing excellent properties such as low density, high strength, high modulus, high temperature resistance, and chemical corrosion resistance, while also exhibiting the flexibility and processability of textile fibers, are increasingly widely used in aerospace, weaponry, and other fields. They serve not only as load-bearing structures but also possess electrical functional properties such as antistatic properties and electromagnetic shielding. During aircraft service, they face various natural environments including high and low temperatures, ultraviolet radiation, and humidity. The electrical conductivity of composite materials is significantly affected by environmental factors such as temperature, humidity, salt spray, and mechanical stress. Ultraviolet radiation may affect the surface conductivity of carbon fiber composites, high-temperature oxidation may alter the conductive pathways, and humid environments can cause the resin matrix to expand, thus deteriorating the conductive network.

[0003] Harsh environmental factors pose significant challenges to the accurate measurement and evaluation of the electrical properties of carbon fiber composites. On the one hand, the anisotropy and microstructural inhomogeneity of carbon fiber composites themselves lead to considerable dispersion in conductivity measurement data. On the other hand, it is difficult to accurately reproduce and measure the effects of various environmental factors (especially under multi-field coupling conditions) on the conductivity of carbon fiber composites in a laboratory environment. Therefore, studying the influence of environmental factors on their conductivity characteristics, particularly their impact on the dynamic conductivity of carbon fiber composites, directly affects the accuracy of simulation calculations of lightning damage to carbon fiber composites and the operational reliability and safety of novel carbon fiber composite aircraft. This research is of paramount importance.

[0004] Regarding the direct lightning effects on carbon fiber composites, EU and US military standards specify the test requirements and lightning current components for direct lightning effects on aircraft or carbon fiber composites used in aircraft. These components include a 200kA lightning current component A (first lightning return stroke component) or a 150kA lightning current component Ah (transitional component of the first lightning return stroke), a 2kA average current component B (intermediate current component), a 200-800A lightning current C / C* (continuous current component), and a 100kA lightning current component D (subsequent return stroke component). However, there are no standards for the test methods and measurement techniques for the dynamic conductivity / resistance of carbon fiber composites, and the dynamic conductivity / resistance under non-destructive lightning current.

[0005] The dynamic resistance of carbon fiber composites is a key characteristic parameter of lightning current shunting under lightning strikes, and it also affects their mechanical strength, significantly influencing the delamination damage caused by lightning current. However, the quantitative relationship between the dynamic conductivity of carbon fiber composites and environmental factors such as ambient temperature, humidity, and long-term ultraviolet radiation has not been obtained, greatly hindering the improvement of carbon fiber composite manufacturing processes, the prediction of degradation levels and safe service life, and failing to provide support for the reliable operation of new carbon fiber composite aircraft, thus restricting their application in aviation, aerospace, and other fields. Summary of the Invention

[0006] To address the issues of missing data and patterns regarding the influence of environmental factors on the electrical conductivity of existing carbon fiber composites, which affects the accuracy of lightning damage simulation analysis and the accuracy of multi-factor lightning damage assessment, the purpose of this invention is to provide a multi-factor assessment method for the influence of environmental factors on the dynamic electrical conductivity of carbon fiber composites. This method aims to obtain the intrinsic correlation between the dynamic electrical conductivity of carbon fiber composites and multiple environmental factors, providing support for the simulation calculation of lightning damage to carbon fiber composites, the performance improvement of composite materials, and the design of protective structures.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A multi-factor evaluation method for the influence of all environmental factors on the dynamic electrical conductivity properties of carbon fiber composites includes the following steps: 1) An aging test of carbon fiber composite materials was conducted under constant ambient temperature and different humidity conditions. Test data samples of the effect of humidity on the pulse dynamic conductivity of carbon fiber composite materials were obtained under non-destructive low amplitude pulse voltage / current. 2) Aging tests of carbon fiber composite materials were conducted under constant ambient humidity and different temperature conditions. Test data samples on the effect of humidity on the pulse dynamic conductivity of carbon fiber composite materials were obtained under non-destructive low amplitude pulse voltage / current. 3) Exposed carbon fiber composite material samples to ultraviolet irradiation of different intensities, and used non-destructive low-amplitude pulsed voltage / current to obtain experimental data samples of the pulsed dynamic conductivity of carbon fiber composite materials under ultraviolet irradiation. 4) Repeat the aging test of carbon fiber composite material under different temperature, humidity and ultraviolet irradiation environments described in steps 1) to 3) to obtain test data samples on the effect of environmental factors accelerated aging test on the pulse dynamic conductivity of carbon fiber composite material, obtain the temperature, humidity and ultraviolet irradiation threshold of the pulse dynamic conductivity characteristics of carbon fiber composite material, establish an evaluation model of the change / influence of the pulse dynamic conductivity characteristics of carbon fiber composite material, and the influence law of multiple environmental factors temperature + humidity ultraviolet irradiation on the pulse dynamic conductivity of carbon fiber composite material. 5) Based on the obtained influence law of temperature + humidity and ultraviolet irradiation on the pulse dynamic conductivity of carbon fiber composites, a multi-factor regression model of environmental factors was established. Using the experimental data of pulse dynamic conductivity of carbon fiber composites with temperature + humidity + ultraviolet irradiation intensity, the influence law of temperature, humidity and ultraviolet irradiation intensity and the multi-factor regression coefficient of environmental factors in the aging test were calculated.

[0008] Preferably, in step 1), under a constant ambient temperature, at least five humidity values ​​H1...H5, including the lowest and highest humidity values, are selected within an ambient humidity range of 10%RH to 99%RH for aging tests. The aging time for each humidity value is no less than 1000 hours, and no less than 100 pulse dynamic conductivity test points are conducted within the aging time of each humidity value. The time intervals between the test points are equal or unequal, thereby obtaining test data samples on the effect of humidity at time nodes 1-100 under different humidity values ​​H1...H5 on the pulse dynamic conductivity of carbon fiber composite materials.

[0009] Preferably, in step 2), under a certain ambient humidity, at least five temperature values ​​T1...T5, including the lowest and highest temperature values, are selected within an ambient temperature range of -30℃ to 200℃ for aging tests. The aging time for each temperature value is not less than 1000 hours, and at least 100 pulse dynamic conductivity test points are conducted within the aging time of each temperature value. The time intervals between the test points are equal or unequal, so as to obtain test data samples on the effect of the temperature at the 1st to 100th time nodes of different temperatures T1...T5 on the pulse dynamic conductivity of carbon fiber composite materials.

[0010] Preferably, in step 3), under constant ambient temperature and humidity, the ambient ultraviolet irradiation intensity is 100 W / m². 2 -2000W / m 2 Environmental full-factor UV irradiation aging tests were conducted on carbon fiber composites under at least five irradiation conditions U1…U5, including the lowest and highest UV irradiation values. The UV irradiation aging time for each environment was no less than 1000 hours, and no less than 100 pulse dynamic conductivity test points were conducted within the aging time. The time intervals between the test points were equal or unequal, so as to obtain test data samples of the influence of pulse dynamic conductivity on carbon fiber composites at time nodes 1-100 under UV irradiation aging conditions U1…U5.

[0011] Preferably, step 4) involves obtaining the humidity threshold for accelerated aging of the pulse dynamic conductivity characteristics of carbon fiber composite materials and establishing a humidity change / impact assessment model for the pulse dynamic conductivity characteristics of carbon fiber composite materials. The specific process includes: If, during step 1), the pulse dynamic conductivity of the carbon fiber composite material changes significantly under the humidity conditions as the ambient humidity increases, then the test is repeated at the new effective humidity test point by subtracting 10%RH from the current humidity. If the pulse dynamic conductivity of the carbon fiber composite material does not change under the new effective humidity conditions, then the test is repeated by adding 5%RH to the effective humidity value. This process continues until the highest humidity threshold for accelerated aging of the carbon fiber composite material is finally determined. Regression analysis was performed on the pulse dynamic conductivity data obtained under effective humidity conditions. If the obtained scatter data showed a roughly linear distribution, a linear regression equation was established; if the scatter data showed an initial increase followed by a relatively stable trend, a quadratic polynomial regression model was established; if the scatter data showed an exponential change, an exponential regression model was established.

[0012] Preferably, step 4) involves obtaining the temperature threshold for accelerated aging of the pulse dynamic conductivity characteristics of carbon fiber composite materials and establishing a temperature change / impact assessment model for the pulse dynamic conductivity characteristics of carbon fiber composite materials. The specific process includes: If, in step 2), the change in pulse dynamic conductivity of carbon fiber composite material undergoes significant distortion during the increase of ambient temperature, then 10°C is subtracted from this temperature to obtain a new effective temperature test point for testing; if the pulse dynamic conductivity of carbon fiber composite material does not change at this new effective temperature, then 5°C is added to this effective temperature point for testing, and so on, until the temperature threshold for accelerated aging of carbon fiber composite material is finally determined. Regression analysis was performed on the pulse dynamic conductivity data obtained under effective temperature conditions. If the obtained scatter data is roughly linearly distributed, a linear regression equation was established; if the scatter data shows an initial increase followed by a relatively stable trend, a quadratic polynomial regression model was established; if the scatter data shows an exponential change, an exponential regression model was established.

[0013] Preferably, step 4) involves obtaining the UV irradiation threshold for accelerated aging of the pulse dynamic conductivity characteristics of carbon fiber composite materials and establishing a UV irradiation change / impact assessment model for the pulse dynamic conductivity characteristics of carbon fiber composite materials. The specific process includes: If, in step 3), the pulse dynamic conductivity of the carbon fiber composite material undergoes significant distortion under the increased UV irradiation intensity, then the UV irradiation intensity should be reduced by 100 W / m. 3 The test will be repeated at the new effective UV irradiation intensity test point; if the pulse dynamic conductivity of the carbon fiber composite material does not change under the new effective UV irradiation intensity condition, then this effective humidity point will be increased by 50 W / m. 3 Experiments were conducted, and so on, to ultimately determine the maximum ultraviolet irradiation intensity threshold for humidity-accelerated aging of carbon fiber composite materials. Regression analysis was performed on the pulse dynamic conductivity data obtained under effective ultraviolet irradiation intensity conditions. If the obtained scatter data is roughly linearly distributed, a linear regression equation was established; if the scatter data shows an initial increase followed by a relatively stable trend, a quadratic polynomial regression model was established; if the scatter data shows an exponential change, an exponential regression model was established.

[0014] Preferably, step 1) is repeated 3 times to reduce the dispersion of the sample and obtain pulse dynamic conductivity data of carbon fiber composite material under constant temperature and 5 humidity conditions. Repeat step 2) three times to reduce the dispersion of the sample and obtain pulse dynamic conductivity data of carbon fiber composite material at constant humidity and five temperatures; Repeat step 3) three times to reduce the dispersion of the sample and obtain pulse dynamic conductivity data of carbon fiber composite material under constant ambient temperature, humidity and five ultraviolet irradiation intensities.

[0015] The purpose of this invention is to provide a multi-factor evaluation method for the dynamic conductivity characteristics of carbon fiber composites under all environmental factors. This method studies the influence of environmental factors such as temperature, humidity, and ultraviolet (UV) irradiation on the pulse dynamic conductivity characteristics of carbon fiber composites under non-destructive lightning current components. Single or multiple environmental conditions (temperature, humidity, etc.) are used as experimental conditions for the dynamic conductivity characteristics of carbon fiber composites, ultimately obtaining large-sample data on the influence of single or multiple factors of temperature, humidity, and UV irradiation on the dynamic conductivity of carbon fiber composites. The influence law of environmental factors such as temperature, humidity, and UV irradiation on the pulse dynamic conductivity characteristics of carbon fiber composites is obtained. Based on this, a multi-factor evaluation model of environmental factors for the dynamic conductivity characteristics of carbon fiber composites is established. Accelerated testing methods for environmental temperature, humidity, and UV irradiation are obtained, along with temperature, humidity, and UV irradiation dose thresholds, and the intrinsic correlation between the dynamic conductivity characteristics of carbon fiber composites and multiple environmental factors. This provides support for the simulation calculation of lightning damage to carbon fiber composites, performance improvement of composite materials, and design of protective structures. Attached Figure Description

[0016] Figure 1 This is a flowchart of the accelerated test method for the effects of ambient temperature, humidity, and ultraviolet irradiation on the pulse dynamic conductivity characteristics of carbon fiber composite materials according to the present invention. Figure 2(a) is a schematic diagram of the dynamic conductivity measurement device for carbon fiber composite materials of the present invention; Figure 2(b) is a schematic diagram illustrating the measurement principle of the dynamic conductivity characteristics of the carbon fiber composite material of the present invention; Figure 3 This is a flowchart of the method for analyzing the temperature threshold and influence law of the dynamic conductivity aging test of carbon fiber composite materials according to the present invention; Figure 4This is a flowchart of the method for analyzing the humidity threshold and its influence on the aging test of the dynamic conductivity properties of carbon fiber composite materials according to the present invention. Figure 5 This is a flowchart of the method for analyzing the ultraviolet irradiation threshold and its influence on the aging test of the dynamic conductivity properties of carbon fiber composite materials according to the present invention. Detailed Implementation The test method and measurement principle of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0017] This invention obtains the variation law of dynamic electrical conductivity of carbon fiber composite materials by conducting accelerated aging tests on carbon fiber composite materials under all factors such as ambient temperature, humidity, and ultraviolet irradiation.

[0018] See Figure 1 The multi-factor evaluation method for the influence of all environmental factors on the dynamic conductivity of carbon fiber composites includes two parts: accelerated aging test method for carbon fiber composites under all environmental factors such as temperature, humidity, and ultraviolet irradiation, and analysis method for the influence of temperature, humidity, and ultraviolet irradiation intensity of environmental aging test on the dynamic conductivity of carbon fiber composites. The accelerated aging test method for carbon fiber composites under different ambient temperatures, humidity levels, and ultraviolet irradiation is as follows: 1. Experimental data on the influence of ambient humidity on the pulse dynamic conductivity characteristics of carbon fiber composite materials were obtained under constant ambient temperature.

[0019] 1) Selection of ambient temperature: It is advisable to conduct the test at a normal temperature of 25℃.

[0020] 2) The ambient humidity ranges from 10%RH to 99%RH. At least five humidity values ​​are selected within this range, but at least the lowest and highest humidity points are included.

[0021] 3) The humidity aging time shall be no less than 1000 hours, and no less than 100 pulse dynamic conductivity test points shall be performed within the aging time. The time interval between the test points can be equal, denoted as . n =1, 2, ..., 99, 100.

[0022] 4) Set up 10 pulse dynamic conductivity measurements of carbon fiber composite materials, and record the measurement data as σ. 25THmn ,in: m Select at least 5 humidity condition points. n The number of data points detected during the aging test (no less than 100 points).

[0023] 5) Conduct the first aging test under the set humidity H1 condition. When the first time point of the 1000hr aging time is reached, measure the pulse dynamic conductivity σ of the carbon fiber composite material. IMP25TH11 ..., until the 100th time node is reached, the pulse dynamic conductivity σ of the carbon fiber composite material is measured. IMP25TH1100 .

[0024] 6) Repeat step 5) to conduct the aging test under the first humidity H1 condition. When the second time point is reached within the 1000hr aging time, measure the pulse dynamic conductivity σ of the carbon fiber composite material. IMP25TH21 The experiment was repeated, and when the 10th time point of the 1000-hour aging period was reached, the pulse dynamic conductivity σ of the carbon fiber composite material was measured at the 100th time point. IMP25TH2100 .

[0025] 7) Repeat steps 5) and 6) above to conduct experiments on the variation law of pulse dynamic conductivity characteristics of carbon fiber composites under the second humidity conditions from H2 to H5; finally, obtain the pulse dynamic conductivity σ of carbon fiber composites at time nodes 1-100 under humidity conditions H1...H5. IMP25H11 , ..., σ IMP25H1100 ... and pulse dynamic conductance σ IMP25TH51 , ..., σ IMP25TH5100 .

[0026] 2. Under constant ambient humidity, investigate the influence of ambient temperature on the pulse dynamic conductivity characteristics of carbon fiber composite materials.

[0027] 1) Selection of ambient humidity: An average ambient humidity of 60%RH can be considered.

[0028] 2) The ambient temperature range covers the harsh environmental temperatures of the aircraft, from -30℃ to 60℃. Considering that in an oxygen-rich environment (such as air), the decomposition temperature is significantly reduced due to the thermal oxidation and decomposition of the resin, typically starting at 180-200℃, the upper limit of the environmentally accelerated aging temperature for carbon fiber composite materials is set at 200℃. At least [amount missing] within the range of -30℃ to 200℃ is selected. m Environmental aging tests of carbon fiber composite materials were conducted at a temperature condition of 5, denoted as . m =1, 2, ..., 5.

[0029] 3) The aging time at ambient temperature shall not be less than 1000 hours, and within the aging time, an aging process of not less than [amount missing] hours shall be conducted. n The test points for the pulse dynamic conductivity characteristic of 100 are equidistant from each other, and the time interval between the test points can be denoted as . n =1, 2, ..., 99, 100.

[0030] 4) During the environmental temperature aging test of carbon fiber composite materials, the measured data is recorded as σ. 60HTmn ,in, m =1, 2, ..., 5, n =1, 2, ..., 99, 100 5) Conduct an aging test on the carbon fiber composite material under the first set temperature T1. When the first time point within the 1000hr aging time is reached, measure the pulse dynamic conductivity σ of the carbon fiber composite material. IMP60HT11 .

[0031] 6) Repeat step 5) to conduct the aging test of the carbon fiber composite material at the first temperature T1. When the second time node is reached within the 1000hr temperature aging time, measure the pulse dynamic conductivity σ of the carbon fiber composite material. IMP60HT12 The experiment was repeated... When the 100th time point of the 1000-hr temperature aging period was reached, the pulse dynamic conductivity σ of the carbon fiber composite material at the 100th time point was measured. IMP60HT1100 .

[0032] 7) By repeating the temperature aging tests in steps 5) and 6), the pulse dynamic conductivity σ of the carbon fiber composite material at time nodes 1-100 under ambient temperature aging conditions T1...T5 can be obtained. IMP60HT11 , ..., σ IMP60HT1100 ...until the pulse dynamics σ of the carbon fiber composite material at constant humidity and the 5th ambient temperature. IMP60HT51 , ..., σ IMP60HT5100 .

[0033] 3. Obtain test data on the pulse dynamic conductivity characteristics of carbon fiber composite materials under constant ambient temperature and humidity.

[0034] 1) Selection of ambient ultraviolet radiation intensity: 100W / m² can be considered within the radiation intensity range. 2 -2000W / m 2 conduct.

[0035] 2) At 100W / m 2 -2000W / m 2 Select at least within the ultraviolet irradiation range m Environmental full-factor UV irradiation aging test of carbon fiber composites under 5 irradiation conditions, denoted as m =1, 2, ..., 5.

[0036] 3) The environmental ultraviolet irradiation aging time shall not be less than 1000 hours, and within the aging time, an irradiation process of not less than [amount missing] hours shall be carried out. nThe test points represent the dynamic conductivity characteristic of 100, and the time intervals between the test points can be equal, denoted as . n =1, 2, ..., 99, 100.

[0037] 4) During the environmental ultraviolet irradiation aging test of carbon fiber composite materials, the measured data is recorded as σ. ImpUTmn ,in, m =1, 2, ..., 5, n =1, 2, ..., 99, 100 5) Conduct the first aging test of the carbon fiber composite material under the set ultraviolet irradiation U1 condition. When the first time node is reached within the 1000hr aging time, measure the pulse dynamic conductivity σ of the carbon fiber composite material. ImpU11 .

[0038] 6) Repeat step 5) to conduct the aging test of the carbon fiber composite material under the first temperature U1 condition. When the second time node is reached within the 1000hr temperature aging time, measure the pulse dynamic conductivity σ of the carbon fiber composite material. ImpU12 The experiment was repeated... When the 100th time point of the 1000-hr temperature aging period was reached, the pulse dynamic conductivity σ of the carbon fiber composite material at the 100th time point was measured. ImpU1100 .

[0039] 7) By repeating the temperature aging tests in steps 5) and 6), the pulse dynamic conductivity σ of the carbon fiber composite material at time nodes 1-100 under ambient temperature aging conditions U1...U5 can be obtained. ImpU11 , ..., σ ImpU100 ...until the pulse dynamic conductivity σ of carbon fiber composite material under constant humidity and the 5th ambient ultraviolet irradiation. ImpU51 , ..., σ ImpU5100 .

[0040] 4. Data acquisition from multifactor regression analysis of environmental all-factor aging tests 1) Humidity acceleration threshold and data on the dynamic conductivity of carbon fiber composites (1) Under normal circumstances, for carbon fiber composites with layered structures, since the temperature resistance of carbon fiber materials is much higher than that of interlayer resin materials, the change of humidity has little effect on the properties of carbon fiber materials. Therefore, this application focuses on the effect of humidity change on the dynamic conductivity characteristics of carbon fiber composites in the thickness direction. In other words, unless otherwise specified, the pulse dynamic conductivity in this application specifically refers to the pulse dynamic conductivity in the thickness direction of carbon fiber composites.

[0041] (2) Repeat process 2 for 3 ( i=3) tests were conducted to reduce the dispersion of the samples, and the pulse dynamic conductivity data of carbon fiber composites were obtained under constant temperature (25℃) and 5 humidity levels (10%-99%RH). Pulse dynamic conductivity σ Imp25TH11i , ..., σ Imp25TH1100i ... until the pulse dynamic conductance σ Imp25TH51i , ..., σ Imp25TH5100i .

[0042] 2) Temperature acceleration factor and data on the dynamic conductivity of carbon fiber composites (1) Similarly, this application focuses on the effect of temperature change on the dynamic conductivity characteristics of carbon fiber composite material in the thickness direction. In other words, without further explanation, in the temperature accelerated aging test of this application, pulse dynamic conductivity also specifically refers to the dynamic conductivity characteristics of carbon fiber composite material in the thickness direction.

[0043] (2) Repeat process 2 for 3 ( i =3) tests were conducted to reduce sample dispersion, and pulse dynamic conductivity data σ of carbon fiber composites were obtained at constant humidity (average humidity 60%) and 5 temperatures (-30℃-200℃). Imp60HT11i , ..., σ Imp60HT100i ...until the pulse dynamic conductivity σ of the carbon fiber composite material at constant humidity and the 5th ambient temperature. Imp60HT51i , ..., σ Imp60HT5100i .

[0044] 3) Data on the effects of ultraviolet irradiation acceleration factor and temperature on the dynamic conductivity properties of carbon fiber composites (1) Ultraviolet irradiation Similarly, this application focuses on the effect of ultraviolet irradiation aging on the dynamic electrical conductivity of carbon fiber composite materials in the thickness direction.

[0045] (2) Repeat process 2 for 3 ( i =3) tests were conducted to reduce sample dispersion, and 5 ultraviolet irradiation intensities (100W / m²) were obtained. 2 -2000W / m 2 The pulse dynamic conductivity data σ of carbon fiber composite materials obtained under the following conditions ImpU11i , ..., σ ImpU100i ...until the pulse dynamic conductivity σ of the carbon fiber composite material under the 5th ultraviolet irradiation intensity. ImpU51i , ..., σ ImpU5100i .

[0046] Referring to Figures 2(a) and 2(b), the dynamic conductivity characteristics of triaxial carbon fiber composite materials were measured according to the invention patent ZL 201510453885.5, "Method and Device for Measuring Impedance Characteristics of Carbon Fiber Composite Materials under Non-destructive Lightning Current". The dynamic conductivity measurement device mainly consists of a controllable DC high-voltage charging circuit 1, a pulse current discharge unit 2, a carbon fiber composite material 3, a control unit 4, a measurement unit 5, and a computer data processing unit 6. Specifically, the controllable DC high-voltage charging circuit 1 comprises a voltage regulator T1, a transformer T2, a rectifier silicon stack D, and a charging resistor. R 1. Components: Switch S and resistor R 2. A safe discharge circuit for the energy storage capacitor is formed; the energy storage capacitor 2 (capacity C), the discharge switch 3, the waveform forming inductor 5 (inductance L), and the waveform forming resistor 4 (resistance R) form a pulse current discharge circuit. The waveform of the pulse current can be the 8 / 20μs standard lightning current waveform in the power field, or the 6.4 / 69μs lightning current A component waveform or the 3.2 / 34.5μs lightning current D component waveform, etc., used in direct lightning effect tests in the aviation field.

[0047] The specific method and procedure for testing the pulse dynamic conductivity of carbon fiber composite materials refer to the invention patent ZL201510453885.5, "Method and device for measuring the impedance characteristics of carbon fiber composite materials under non-destructive lightning current".

[0048] See Figure 3 , Figure 4 , Figure 5 The temperature, humidity, ultraviolet irradiation intensity threshold, and multi-factor regression method are used to analyze the dynamic electrical conductivity properties of carbon fiber composites. The specific analysis methods are as follows: 1) Analysis of the influence of humidity on the dynamic conductivity of carbon fiber composites: The humidity threshold for accelerated aging of the dynamic conductivity of carbon fiber composites and the influence of humidity on the dynamic conductivity of carbon fiber composites were obtained.

[0049] (1) If the pulse dynamic conductivity of carbon fiber composite material changes significantly under the humidity conditions during the increase of ambient humidity, the test point is to be reduced by 10%RH to the humidity and then retested; if the pulse dynamic conductivity of carbon fiber composite material does not change under the new effective humidity conditions, the test point is to be increased by 5%RH and then retested, and so on, until the highest humidity threshold for accelerated aging of carbon fiber composite material is finally determined.

[0050] (2) Regression analysis is performed on the pulse dynamic conductivity data obtained under effective humidity conditions. If the obtained scatter data is roughly linearly distributed, a linear regression equation is established. If the scatter data shows an increase followed by a relatively stable trend, a quadratic polynomial regression model can be established. If the scatter data shows an exponential change pattern, an exponential regression model is adopted.

[0051] 2) Analysis of the effect of temperature on the dynamic conductivity of carbon fiber composites: The temperature threshold for accelerated aging of the dynamic conductivity of carbon fiber composites and the influence of temperature on the dynamic conductivity of carbon fiber composites were obtained.

[0052] (1) If the change in pulse dynamic conductivity of carbon fiber composite material is significantly distorted during the increase of ambient temperature, then 10℃ is subtracted from the temperature as the new effective temperature test point for testing; if the pulse dynamic conductivity of carbon fiber composite material is not distorted at the new effective temperature, then 5℃ is added to this effective temperature point for testing, and so on... Finally, the temperature threshold for accelerated aging of carbon fiber composite material is determined.

[0053] (2) Regression analysis is performed on the pulse dynamic conductivity data obtained under effective temperature conditions. If the obtained scatter data is roughly linearly distributed, a linear regression equation is established. If the scatter data shows an increase followed by a relatively stable trend, a quadratic polynomial regression model can be established. If the scatter data shows an exponential change pattern, an exponential regression model is adopted.

[0054] 3) Analysis of the influence of ultraviolet irradiation on the dynamic conductivity of carbon fiber composites: The ultraviolet irradiation threshold for accelerated aging of the dynamic conductivity of carbon fiber composites and the influence of ultraviolet irradiation intensity on the dynamic conductivity of carbon fiber composites were obtained.

[0055] (1) If the pulse dynamic conductivity of the carbon fiber composite material changes significantly under the ultraviolet irradiation intensity as the ultraviolet irradiation intensity increases, then the ultraviolet irradiation intensity should be reduced by 100 W / m. 3 The test will be repeated at the new effective UV irradiation intensity test point; if the pulse dynamic conductivity of the carbon fiber composite material does not change under the new effective UV irradiation intensity condition, then this effective humidity point will be increased by 50 W / m. 3 Experiments were conducted, and so on, until the highest UV irradiation intensity threshold for humidity-accelerated aging of carbon fiber composite materials was finally determined.

[0056] (2) Regression analysis is performed on the pulse dynamic conductivity data obtained under effective ultraviolet irradiation intensity. If the obtained scatter data is roughly linearly distributed, a linear regression equation is established. If the scatter data shows an increase followed by a relatively stable trend, a quadratic polynomial regression model can be established. If the scatter data shows an exponential change pattern, an exponential regression model is adopted.

[0057] 4) The influence of environmental temperature factors on the pulse dynamic conductivity of carbon fiber composite materials Based on the obtained influence of temperature and humidity ultraviolet irradiation on the pulse dynamic conductivity of carbon fiber composite materials, a multi-factor regression model combining all environmental factors was established.

[0058] Using pulse dynamic conductivity test data of carbon fiber composite materials combined with temperature, humidity and ultraviolet irradiation intensity, the influence of multiple factors such as temperature, humidity and ultraviolet irradiation intensity and the multi-factor regression coefficients of environmental all-factor aging test were calculated.

Claims

1. A multi-factor evaluation method for the influence of all environmental factors on the dynamic conductivity properties of carbon fiber composites, characterized in that... Includes the following steps: 1) An aging test of carbon fiber composite materials was conducted under constant ambient temperature and different humidity conditions. Test data samples of the effect of humidity on the pulse dynamic conductivity of carbon fiber composite materials were obtained under non-destructive low amplitude pulse voltage / current. 2) Aging tests of carbon fiber composite materials were conducted under constant ambient humidity and different temperature conditions. Test data samples on the effect of humidity on the pulse dynamic conductivity of carbon fiber composite materials were obtained under non-destructive low amplitude pulse voltage / current. 3) Exposed carbon fiber composite material samples to ultraviolet irradiation of different intensities, and used non-destructive low-amplitude pulsed voltage / current to obtain experimental data samples of the pulsed dynamic conductivity of carbon fiber composite materials under ultraviolet irradiation. 4) Repeat the aging test of carbon fiber composite material under different temperature, humidity and ultraviolet irradiation environments described in steps 1) to 3) to obtain test data samples on the effect of environmental factors accelerated aging test on the pulse dynamic conductivity of carbon fiber composite material, obtain the temperature, humidity and ultraviolet irradiation threshold of the pulse dynamic conductivity characteristics of carbon fiber composite material, establish an evaluation model of the change / influence of the pulse dynamic conductivity characteristics of carbon fiber composite material, and the influence law of multiple environmental factors temperature + humidity ultraviolet irradiation on the pulse dynamic conductivity of carbon fiber composite material. 5) Based on the obtained influence law of temperature + humidity and ultraviolet irradiation on the pulse dynamic conductivity of carbon fiber composites, a multi-factor regression model of environmental factors was established. Using the experimental data of pulse dynamic conductivity of carbon fiber composites with temperature + humidity + ultraviolet irradiation intensity, the influence law of temperature, humidity and ultraviolet irradiation intensity and the multi-factor regression coefficient of environmental factors in the aging test were calculated.

2. The multi-factor evaluation method for the influence of all environmental factors on the dynamic conductivity properties of carbon fiber composite materials according to claim 1, characterized in that: In step 1), under a constant ambient temperature, at least five humidity values ​​H1...H5, including the lowest and highest humidity values, are selected within an ambient humidity range of 10%RH to 99%RH for aging tests. The aging time for each humidity value is no less than 1000 hours, and no less than 100 pulse dynamic conductivity test points are conducted within the aging time of each humidity value. The time intervals between the test points are equal or unequal, so as to obtain test data samples of the influence of humidity at time nodes 1-100 under different humidity values ​​H1...H5 on the pulse dynamic conductivity of carbon fiber composite materials.

3. The multi-factor evaluation method for the influence of all environmental factors on the dynamic conductivity properties of carbon fiber composites according to claim 1, characterized in that: In step 2), under constant ambient humidity, at least five temperature values ​​T1 to T5, including the lowest and highest temperature values, are selected within the ambient temperature range of -30℃ to 200℃ for aging tests. The aging time for each temperature value is no less than 1000 hours, and no less than 100 pulse dynamic conductivity test points are conducted within the aging time of each temperature value. The time intervals between the test points are equal or unequal, so as to obtain test data samples of the influence of the temperature at the 1st to 100th time nodes of different temperatures T1 to T5 on the pulse dynamic conductivity of carbon fiber composite materials.

4. The multi-factor evaluation method for the influence of all environmental factors on the dynamic conductivity properties of carbon fiber composites according to claim 1, characterized in that: Step 3) is performed under constant ambient temperature and humidity, with an ambient ultraviolet irradiation intensity of 100 W / m. 2 -2000W / m 2 Environmental full-factor UV irradiation aging tests were conducted on carbon fiber composites under at least five irradiation conditions U1…U5, including the lowest and highest UV irradiation values. The UV irradiation aging time for each environment was no less than 1000 hours, and no less than 100 pulse dynamic conductivity test points were conducted within the aging time. The time intervals between the test points were equal or unequal, so as to obtain test data samples of the influence of pulse dynamic conductivity on carbon fiber composites at time nodes 1-100 under UV irradiation aging conditions U1…U5.

5. The multi-factor evaluation method for the influence of all environmental factors on the dynamic conductivity properties of carbon fiber composite materials according to claim 2, characterized in that, Step 4) involves obtaining the humidity threshold for accelerated aging of the pulse dynamic conductivity characteristics of carbon fiber composite materials and establishing a humidity change / impact assessment model for the pulse dynamic conductivity characteristics of carbon fiber composite materials. The specific process includes: If, during step 1), the pulse dynamic conductivity of the carbon fiber composite material changes significantly under the humidity conditions as the ambient humidity increases, then the test is repeated at the new effective humidity test point by subtracting 10%RH from the current humidity. If the pulse dynamic conductivity of the carbon fiber composite material does not change under the new effective humidity conditions, then the test is repeated by adding 5%RH to the effective humidity value. This process continues until the highest humidity threshold for accelerated aging of the carbon fiber composite material is finally determined. Regression analysis was performed on the pulse dynamic conductivity data obtained under effective humidity conditions. If the obtained scatter data showed a roughly linear distribution, a linear regression equation was established; if the scatter data showed an initial increase followed by a relatively stable trend, a quadratic polynomial regression model was established; if the scatter data showed an exponential change, an exponential regression model was established.

6. The multi-factor evaluation method for the influence of all environmental factors on the dynamic conductivity properties of carbon fiber composite materials according to claim 3, characterized in that, Step 4) involves obtaining the temperature threshold for accelerated aging of the pulse dynamic conductivity characteristics of carbon fiber composites and establishing a temperature change / impact assessment model for the pulse dynamic conductivity characteristics of carbon fiber composites. The specific process includes: If, in step 2), the change in pulse dynamic conductivity of carbon fiber composite material undergoes significant distortion during the increase of ambient temperature, then 10°C is subtracted from this temperature to obtain a new effective temperature test point for testing; if the pulse dynamic conductivity of carbon fiber composite material does not change at this new effective temperature, then 5°C is added to this effective temperature point for testing, and so on, until the temperature threshold for accelerated aging of carbon fiber composite material is finally determined. Regression analysis was performed on the pulse dynamic conductivity data obtained under effective temperature conditions. If the obtained scatter data is roughly linearly distributed, a linear regression equation was established; if the scatter data shows an initial increase followed by a relatively stable trend, a quadratic polynomial regression model was established; if the scatter data shows an exponential change, an exponential regression model was established.

7. The multi-factor evaluation method for the influence of all environmental factors on the dynamic conductivity properties of carbon fiber composites according to claim 4, characterized in that, Step 4) involves obtaining the UV irradiation threshold for accelerated aging of the pulsed dynamic conductivity properties of carbon fiber composites and establishing a UV irradiation change / impact assessment model for the pulsed dynamic conductivity properties of carbon fiber composites. The specific process includes: If, in step 3), the pulse dynamic conductivity of the carbon fiber composite material undergoes significant distortion under the increased UV irradiation intensity, then the UV irradiation intensity should be reduced by 100 W / m. 3 The test will be repeated at the new effective UV irradiation intensity test point; if the pulse dynamic conductivity of the carbon fiber composite material does not change under the new effective UV irradiation intensity condition, then this effective humidity point will be increased by 50 W / m. 3 Experiments were conducted, and so on, to ultimately determine the maximum ultraviolet irradiation intensity threshold for humidity-accelerated aging of carbon fiber composite materials. Regression analysis was performed on the pulse dynamic conductivity data obtained under effective ultraviolet irradiation intensity conditions. If the obtained scatter data is roughly linearly distributed, a linear regression equation was established; if the scatter data shows an initial increase followed by a relatively stable trend, a quadratic polynomial regression model was established; if the scatter data shows an exponential change, an exponential regression model was established.

8. The multi-factor evaluation method for the influence of all environmental factors on the dynamic conductivity properties of carbon fiber composites according to claim 1, characterized in that: Repeat step 1) three times to reduce the dispersion of the sample and obtain pulse dynamic conductivity data of carbon fiber composite material under constant temperature and five humidity conditions. Repeat step 2) three times to reduce the dispersion of the sample and obtain pulse dynamic conductivity data of carbon fiber composite material at constant humidity and five temperatures; Repeat step 3) three times to reduce the dispersion of the sample and obtain pulse dynamic conductivity data of carbon fiber composite material under constant ambient temperature, humidity and five ultraviolet irradiation intensities.

Images