Method and system for equivalent acceleration and life prediction of composite materials in polar multi-field coupling environment

Abstract

The application belongs to the technical field of composite material durability and reliability evaluation, and discloses a composite material equivalent acceleration and life prediction method and system under a polar multi-field coupling environment. The application constructs a natural environment spectrum of a service environment; determines key environmental factors based on the environment spectrum and a damage mechanism, designs and combines a moisture absorption module, a freeze-thaw module, a low-temperature freezing module and an ultraviolet radiation module to form an acceleration test spectrum; performs a multi-cycle accelerated aging test on a sample according to the spectrum, and synchronously applies a mechanical load; tests the performance of the sample after aging by using a high-throughput platform, and obtains attenuation data; based on the equivalent relationship between the data and the acceleration spectrum, a life prediction model is established by fitting a residual strength model and calculating an acceleration coefficient, so as to realize the life prediction of the composite material under the multi-field coupling environment. The application systematically expounds the compilation method of the multi-factor equivalent environment acceleration test spectrum of the composite material in the marine environment, and lays a foundation for the related research on the life prediction of the composite material in the polar low-temperature environment.

Description

Technical Field

[0001] This invention belongs to the field of composite material durability and reliability assessment technology, and particularly relates to the equivalent accelerated testing method and service life prediction method and system for composite materials under polar multi-field coupling environment, especially the damage equivalent accelerated testing method and service life prediction technology for composite materials under complex multi-field coupling environment (especially polar / low temperature marine environment). Background Technology

[0002] With the implementation of my country's polar strategy and the deployment of aviation equipment in polar regions, composite material structures for aircraft such as helicopters and drones are facing severe challenges from extreme environments. The polar environment is characterized by low temperatures, strong ultraviolet radiation, high humidity, salt spray, frequent freeze-thaw cycles, and complex multi-field coupling of mechanical loads, posing unprecedented challenges to the long-term durability and reliability of composite materials.

[0003] Existing technologies for addressing the environmental aging behavior of composite materials mainly suffer from the following problems and shortcomings: (1) Environmental factors are singular and coupling mechanisms are unclear: Most existing studies focus on the effects of single environmental factors (such as constant temperature and humidity, salt spray or ultraviolet) on the performance of composite materials, and have failed to fully reveal the microscopic damage initiation and evolution mechanism of the synergistic and coupled effects of multiple fields of heat, humidity, force and chemical in polar environments. The understanding of the failure mode change law under the coupling of polar characteristic factors such as low temperature, freeze-thaw cycle and dynamic load is still blank.

[0004] (2) Insufficient simulation of accelerated testing methods: Traditional accelerated aging test spectra (such as constant humidity and temperature, neutral salt spray) are mainly designed for temperate or tropical climates, and their environmental stress types, action sequences and magnitudes differ greatly from those of polar environments. Existing methods cannot accurately simulate the unique polar cycle sequence of "low temperature-high humidity-freeze-thaw-strong ultraviolet" and extreme events such as ice sand impact, resulting in inconsistencies between the damage patterns and evolution laws of laboratory accelerated aging and natural environmental aging, and insufficient equivalence and credibility of accelerated tests.

[0005] (3) Lack of damage evolution and life prediction models: In polar environments, the degradation of composite material properties is a multi-scale dynamic process involving micro-interface debonding, meso-crack propagation, and macro-performance deterioration. Existing life prediction models are mostly based on empirical formulas under single-factor or simple acceleration conditions, lacking physical models and prediction methods based on multi-scale damage evolution mechanisms and capable of characterizing multi-field coupled nonlinear effects. This makes it impossible to accurately assess and predict the remaining strength and life of composite materials used in polar regions.

[0006] (4) Lack of high-throughput and high-efficiency assessment methods: The evaluation cycle of polar environment adaptability is long and costly. Traditional single-sample and single-performance testing methods are inefficient. There is a lack of integrated test systems and methods that can simultaneously apply multiple coupled environmental loads and mechanical loads, and can perform high-throughput, parallel, and rapid characterization and analysis of microscopic damage and macroscopic properties of materials. This seriously restricts the rapid evaluation and selection of the polar applicability of new materials and structures.

[0007] In summary, existing technologies fail to provide a comprehensive testing and evaluation method capable of highly simulating the multi-field coupled service environment of polar regions, revealing the multi-scale damage mechanism of materials, and achieving efficient and accurate lifetime prediction. This is precisely the core technical problem that this invention aims to solve. Summary of the Invention

[0008] To overcome the problems existing in related technologies, the present invention discloses an equivalent acceleration and lifetime prediction method and system for composite materials in a polar multi-field coupling environment, the technical solution of which is as follows: This invention is implemented as follows: an equivalent acceleration and lifetime prediction method for composite materials under polar multi-field coupling environments, comprising the following steps: S1. Construct the natural environment spectrum of the target service area, which includes time-varying data of at least two factors among temperature, humidity, ultraviolet radiation, salt spray and freeze-thaw cycles. S2. Based on the statistical analysis of the natural environment spectrum and the correlation analysis of environmental factors and material properties, key environmental factors are identified and corresponding accelerated test modules are designed and combined to form an accelerated test spectrum. S3. Based on the accelerated test spectrum, conduct multi-cycle accelerated aging tests on the composite material samples; S4. Test the mechanical properties of the composite material samples after aging and obtain performance degradation data; S5. Based on the equivalent relationship between performance degradation data and accelerated test spectrum, a life prediction model for composite materials is established to realize life prediction of composite materials under multi-field coupling environment.

[0009] In step S1, the natural environment spectrum of the target service area is constructed, including: Collect long-term meteorological and environmental pollutant data from representative stations in polar or low-temperature marine environments; Statistical analysis of meteorological and environmental pollutant data is conducted to form a comprehensive environmental factor spectrum that includes annual temperature, humidity, ultraviolet radiation, salt deposition, and freeze-thaw day-to-day data.

[0010] In step S2, the accelerated test spectrum consists of at least three combinations of the following: moisture absorption module, freeze-thaw cycle module, low temperature freezing module, and ultraviolet irradiation module; the environmental stress level of each module is determined based on the extreme values ​​of the corresponding factors in the natural environment spectrum or the accelerated equivalence principle.

[0011] Furthermore, the conditions for the moisture absorption module are: temperature 45°C to 80°C, relative humidity ≥95%, and / or carried out in a 5% NaCl solution; The conditions for the freeze-thaw cycle module are: temperature alternation between -40℃ and 20℃, with a 5% NaCl solution as the medium; The temperature of the low-temperature freezing module is ≤-40℃; The ultraviolet irradiation module uses an ultraviolet light source with a wavelength of 340nm.

[0012] In step S3, while the composite material sample is subjected to accelerated aging test, a static or quasi-static tensile load and / or bending load is applied to the sample through a special loading fixture to achieve multi-field coupling accelerated test of force load and environmental load.

[0013] In step S4, the mechanical properties of the aged sample are tested using a high-throughput testing platform. This platform is capable of performing parallel mechanical tests on multiple micro-samples and / or using in-situ high-throughput characterization techniques to perform batch, rapid statistical analysis and identification of microscopic damage to the sample.

[0014] In step S5, the construction of the life prediction model for the composite material includes: Define a damage variable with the mechanical property retention rate as a metric. Based on accelerated aging test data, the law of change of damage variables with accelerated test time was obtained by fitting. By comparing the exposure time in the natural environment with the laboratory accelerated test time under the same damage variables, the accelerated equivalent coefficient is calculated, thereby establishing the equivalent relationship for life prediction.

[0015] Furthermore, the residual strength empirical model used for fitting is as follows: ;

[0016] In the formula, Aging of composite materials Intensity value after time, This represents the initial strength value of the composite material. These are the model parameters determined by fitting experimental data. For time.

[0017] Another objective of this invention is to provide an equivalent acceleration and lifetime prediction system for composite materials under polar multi-field coupling environments. This system is used to implement the aforementioned method for equivalent acceleration and lifetime prediction of composite materials under polar multi-field coupling environments. The system includes: The environmental spectrum construction and processing module is used to generate and process natural environmental spectra and accelerated test spectra. The key factor analysis module is used to perform statistical and correlation analysis on the natural environment spectrum to output key environmental factors; The multi-field coupled environment test chamber group includes at least a temperature and humidity control chamber, a freeze-thaw cycle chamber, an ultra-low temperature chamber, and an ultraviolet aging chamber, for performing the accelerated test spectrum; The mechanical property testing module is used to test the mechanical properties of aged samples. The data processing and life prediction module is used to process test data, run the life prediction model, and output the life prediction results of the composite material.

[0018] The system also includes: A multi-functional loading fixture is installed in a multi-field coupling environment test chamber to simultaneously apply set tensile and / or bending loads to multiple samples during accelerated aging. The central control unit is used to uniformly schedule and control the multi-field coupling environment test chamber, multi-functional loading fixtures and mechanical performance testing modules, and automatically execute the test process according to the preset test spectrum.

[0019] Combining all the above technical solutions, the beneficial effects of this invention are as follows: First, this invention conducts an adaptability study of composite materials in polar low-temperature marine environments. It involves surveying, screening, simplifying, and statistically analyzing characteristic data of polar low-temperature marine environments to compile a spectrum of natural environmental factors for typical polar environments. Combined with the structural characteristics of composite materials and environmental damage mechanisms, a multi-factor equivalent accelerated environmental test spectrum for marine environments is developed. This invention systematically elucidates the method for compiling multi-factor equivalent accelerated environmental test spectra of composite materials in marine environments, laying the foundation for research on performance degradation, damage mechanisms, and lifespan prediction of composite materials under polar low-temperature environments.

[0020] Secondly, the equivalent acceleration and lifetime prediction method and system for composite materials in polar multi-field coupling environments provided by this invention have the following significant advantages and technical effects: (1) High environmental simulation and accurate damage mechanism reproduction: By systematically analyzing real polar environmental data, a "natural environment spectrum" including temperature, humidity, ultraviolet, salt spray and freeze-thaw cycle was constructed, and a "multi-module combination of accelerated test spectrum" was designed accordingly. This spectrum can highly reproduce the harsh service environment of "heat-humidity-mechanical-chemical" multi-field coupling and time-series alternation unique to the polar region, so that the damage mode generated by accelerated aging in the laboratory (such as fiber / matrix interface debonding, interlayer cracking, matrix cracking) is consistent with the damage characteristics under polar natural environment exposure, fundamentally solving the problems of insufficient simulation and mechanism distortion in traditional single-factor accelerated test.

[0021] (2) Accelerated testing possesses scientific equivalence and strong predictive reliability. This invention innovatively establishes an equivalent acceleration relationship between laboratory accelerated testing and natural environmental aging based on the core principle of "damage equivalence." By defining and monitoring the mechanical property retention rate as a damage variable, and using a fitting model to back-calculate, this invention can calculate an acceleration coefficient with clear physical meaning. This ensures that short-term laboratory testing can equivalently replace the effects of natural environmental aging that last for several years, giving the life prediction results a solid experimental basis and high reliability.

[0022] (3) The life prediction model combines physical mechanisms with engineering practicality; the life prediction model adopted in this invention (such as the Guniev empirical formula) is rooted in the physical laws of reversible and irreversible damage evolution during the aging process of composite materials. The model obtains parameters by fitting multi-cycle accelerated test data, which can accurately describe the nonlinear trajectory of performance degradation. The model is simple in form and has clear parameters. It can reveal the macroscopic laws of damage accumulation and can be conveniently used for residual strength assessment and service life extrapolation in engineering practice, thus achieving the unity of mechanism and application.

[0023] (4) The evaluation efficiency is significantly improved, supporting rapid research and development and selection. This invention integrates a "force environment" coupled loading fixture with a "high-throughput" micro-sample parallel testing system. A single test can simultaneously complete the aging and testing of multiple samples under different stress states, and use advanced characterization techniques to obtain micro-damage information in batches. This system transforms the traditional sequential, low-throughput evaluation process into a parallel, high-throughput, and efficient mode, greatly shortening the environmental adaptability evaluation cycle of materials or components, and providing a powerful tool for the rapid screening, optimized design, and reliability verification of composite materials for polar equipment.

[0024] (5) High system integration, good automation and standardization; This invention integrates environmental spectrum construction, multi-field coupling test, high-throughput testing and data modeling analysis into a complete system. Through the central control unit, it can realize full automation from environmental spectrum analysis to automatic test execution, automatic data acquisition and processing, reducing human intervention, ensuring the consistency of the test process and the repeatability of the results, and laying the foundation for establishing a standardized evaluation system for polar composite materials. This invention systematically solves the problem of predicting the life of composite materials in polar environments through highly simulated multi-field coupling acceleration environment, scientific acceleration method based on damage equivalence, mechanism and data-driven prediction model and high-throughput integrated evaluation system. It can more realistically, quickly, accurately and efficiently evaluate and predict the durability of composite materials in polar environments, and has significant engineering application value and economic benefits.

[0025] Third, this invention can provide manufacturers, research institutes, and testing and certification bodies in the fields of aviation, aerospace, shipbuilding, polar equipment, and new energy (such as offshore wind power) with complete sets of "accelerated testing and life prediction system" hardware, dedicated software, and database subscription services. It provides life prediction and health management support for composite material structures of aircraft, ships, and accommodation facilities used in polar scientific expeditions and resource development, significantly reducing operational risks and the probability of catastrophic accidents caused by material failure, ensuring the safety of personnel and assets, and possessing immense strategic value. Existing accelerated aging test standards at home and abroad (such as constant temperature and humidity, neutral salt spray, and ultraviolet aging) are all designed for temperate or general environments, with single environmental factors and simple action modes. There is a lack of accelerated test spectrum compilation methods that can simultaneously reproduce the temporal alternation and synergistic effects of multiple factors such as "low temperature freezing - high humidity absorption - salt spray corrosion - strong ultraviolet radiation - frequent freeze-thaw cycles." Attached Figure Description

[0026] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure; Figure 1 This is a flowchart of the equivalent acceleration and lifetime prediction method for composite materials in a polar multi-field coupling environment provided in this embodiment of the invention; Figure 2 This is a roadmap for establishing the spectrum of natural environmental factors in typical polar environments provided in this embodiment of the invention; Figure 3 This is a roadmap for constructing a multi-factor equivalent environmental accelerated test spectrum for the marine environment provided in this embodiment of the invention; Figure 4 This is a schematic diagram showing the correspondence between environmental factors and accelerated testing modules provided in an embodiment of the present invention; Figure 5These are median tensile strength curves of composite materials after three equivalent accelerated tests provided in the embodiments of the present invention; wherein, (a) is Scheme 1, (b) is Scheme 2, and (c) is Scheme 3; Figure 6 These are median tensile strength curves of composite materials after three equivalent accelerated tests provided in the embodiments of the present invention; wherein, (a) is Scheme 1, (b) is Scheme 2, and (c) is Scheme 3; Figure 7 This is a schematic diagram of the tension-bending loading fixture provided in an embodiment of the present invention; Figure 8 This is a schematic diagram of environmental load setting provided by an embodiment of the present invention; wherein, (a) is Scheme 1, (b) is Scheme 2, and (c) is Scheme 3; Figure 9 This is a median curve of the strength retention rate of high-throughput composite material T700 after aging under scheme one after applying load, provided in the embodiments of the present invention. Figure 10 This is a median strength retention curve of high-throughput composite material T700 after aging under scheme one without applied load, provided in an embodiment of the present invention. Detailed Implementation

[0027] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0028] The composite material in this invention mainly refers to fiber-reinforced resin-based composite materials with high-performance fibers as reinforcement and polymer resin as matrix. The reinforcement includes, but is not limited to, carbon fibers, glass fibers, aramid fibers, basalt fibers, or hybrid fibers thereof; the matrix resin includes, but is not limited to, epoxy resin, bismaleimide resin, polyimide resin, vinyl ester resin, or unsaturated polyester resin.

[0029] The composite materials typically exist in the form of laminates, sandwich structures, or molded components. It should be understood that the equivalent acceleration and lifetime prediction method provided by this invention is also applicable to other composite material systems with similar interface structures and environmentally sensitive characteristics.

[0030] The innovation of this invention lies in the following: Based on the construction path of natural environment spectrum analysis, key factor screening (grey relational analysis), and modular accelerated spectrum synthesis, this invention establishes an equivalent criterion with the mechanical property retention rate as the unified damage variable, based on the accelerated spectrum of four modules: moisture absorption, freeze-thaw cycle, low temperature freezing, and ultraviolet irradiation, which are combined according to the typical time sequence of natural environment occurrence (moisture absorption → freeze-thaw → freezing → ultraviolet). This enables the equivalent acceleration and lifetime prediction of composite materials coupled with multiple factors of moisture, heat, mechanics, and chemical processes in polar and marine environments.

[0031] Example 1, as Figure 1 As shown in the figure, the equivalent acceleration and lifetime prediction method for composite materials in a polar multi-field coupling environment provided by the present invention includes the following steps: S1. Construct the natural environment spectrum of the target service area, which includes time-varying data of at least two factors among temperature, humidity, ultraviolet radiation, salt spray and freeze-thaw cycles. S2. Based on the statistical analysis of the natural environment spectrum and the correlation analysis of environmental factors and material properties, key environmental factors are identified and corresponding accelerated test modules are designed and combined to form an accelerated test spectrum. S3. Based on the accelerated test spectrum, conduct multi-cycle accelerated aging tests on the composite material samples; S4. Test the mechanical properties of the composite material samples after aging and obtain performance degradation data; S5. Based on the equivalent relationship between performance degradation data and accelerated test spectrum, a life prediction model for composite materials is established to realize life prediction of composite materials under multi-field coupling environment.

[0032] In step S1, the construction of the natural environment spectrum of the target service area includes: Collect long-term meteorological and environmental pollutant data from representative stations in polar or low-temperature marine environments; Statistical analysis of meteorological and environmental pollutant data is conducted to form a comprehensive environmental factor spectrum that includes annual temperature, humidity, ultraviolet radiation, salt deposition, and freeze-thaw day-to-day data.

[0033] In step S2, the accelerated test spectrum consists of at least three combinations of the following: moisture absorption module, freeze-thaw cycle module, low temperature freezing module, and ultraviolet irradiation module; the environmental stress level of each module is determined based on the extreme values ​​of the corresponding factors in the natural environment spectrum or the accelerated equivalence principle.

[0034] Furthermore, the conditions for the moisture absorption module are: temperature 45°C to 80°C, relative humidity ≥95%, and / or carried out in a 5% NaCl solution; The conditions for the freeze-thaw cycle module are: temperature alternation between -40℃ and 20℃, with a 5% NaCl solution as the medium; The temperature of the low-temperature freezing module is ≤-40℃; The ultraviolet irradiation module uses an ultraviolet light source with a wavelength of 340nm.

[0035] In step S3, while the composite material sample is subjected to accelerated aging test, a static or quasi-static tensile load and / or bending load is applied to the sample through a special loading fixture to achieve multi-field coupling accelerated test of force load and environmental load.

[0036] In step S4, the mechanical properties of the aged sample are tested using a high-throughput testing platform. This platform is capable of performing parallel mechanical tests on multiple micro-samples and / or using in-situ high-throughput characterization techniques to perform batch, rapid statistical analysis and identification of microscopic damage to the sample.

[0037] In step S5, the construction of the life prediction model for the composite material includes: Define a damage variable with the mechanical property retention rate as a metric. Based on accelerated aging test data, the law of change of damage variables with accelerated test time was obtained by fitting. By comparing the exposure time in the natural environment with the laboratory accelerated test time under the same damage variables, the accelerated equivalent coefficient is calculated, thereby establishing the equivalent relationship for life prediction.

[0038] Furthermore, the residual strength empirical model used for fitting is as follows: ;

[0039] In the formula, Aging of composite materials Intensity value after time, This represents the initial strength value of the composite material. These are the model parameters determined by fitting experimental data. For time.

[0040] Example 2: The equivalent acceleration and lifetime prediction system for composite materials in a polar multi-field coupling environment provided in this embodiment of the invention includes: The environmental spectrum construction and processing module is used to generate and process natural environmental spectra and accelerated test spectra. The key factor analysis module is used to perform statistical and correlation analysis on the natural environment spectrum to output key environmental factors; The multi-field coupled environment test chamber group includes at least a temperature and humidity control chamber, a freeze-thaw cycle chamber, an ultra-low temperature chamber, and an ultraviolet aging chamber, for performing the accelerated test spectrum; The mechanical property testing module is used to test the mechanical properties of aged samples. The data processing and life prediction module is used to process test data, run the life prediction model, and output the life prediction results of the composite material.

[0041] Furthermore, the system also includes: A multi-functional loading fixture is installed in a multi-field coupling environment test chamber to simultaneously apply set tensile and / or bending loads to multiple samples during accelerated aging. The central control unit is used to uniformly schedule and control the multi-field coupling environment test chamber, multi-functional loading fixtures and mechanical performance testing modules, and automatically execute the test process according to the preset test spectrum.

[0042] To further demonstrate the positive effects of the above embodiments, the present invention conducts the following experiments based on the above technical solutions.

[0043] Experiment 1: Analysis of the characteristics of the polar low-temperature marine environment and establishment of the environmental spectrum; 1.1 Survey and analysis of the polar natural environment; The establishment of a spectrum of natural environmental factors in typical polar environments, such as Figure 2 As shown, we first conducted a survey and analysis of the polar natural environment. Based on this, we selected representative stations (Zhongshan Station and Vostok Station in Antarctica) to compile environmental spectra of single factors of polar low-temperature marine environment, as well as chronological spectra of polar low-temperature marine environmental factors.

[0044] Compared to mid- and low-latitude marine environments, polar environments are characterized by lower temperatures and features such as ice condensation and melting, ice cover, environmental loads, thermal loads, and significant periodic seasonal variations. This unique and extreme environment not only makes the replacement and maintenance of equipment materials difficult, but the resulting material corrosion, changes in fracture modes and mechanisms may lead to premature equipment failure, thereby triggering catastrophic accidents.

[0045] Atmospheric ions also have a crucial impact on the corrosion of helicopter structural materials. Polluting ions, especially Cl-, are particularly significant. - SO4 2- NO 3- NH4 + The presence of plasma has a greater impact on the corrosion behavior and mechanism of metals. In recent years, pollutant ions in Antarctic atmospheric aerosols have been continuously increasing, and Antarctic precipitation and snow cover contain Cl... - NO3 - SO4 2- Plasma. Studies of aerosols at Zhongshan Station in Antarctica from 2005 to 2008 showed that sea salt was its main component, with sea salt ions (Na+) being the most abundant. + Mg 2+ Ca 2+ and Cl -The highest concentration was observed in March, with the highest average concentration in September, including a Cl ion concentration. - Na + SO4 2- >Mg 2+ NO3 - >K + >Ca 2+ >NH 4+ In the Antarctic coastal region Na + Cl - K + and Ca 2+ It mainly comes from sea salt. Antarctic snow also contains chemical substances, the formation of which is quite complex. For example, NO3... - For example, lightning, lower stratosphere NO x The deposition of nitrogen-containing compounds and their global transport contribute to the presence of NO3- in Antarctic snow. - The presence of NO3 was investigated by examining the atmosphere (aerosols) and snow cover in the East Antarctic Plain (Dome C) region. - The source and results showed that NO3 was present. - The ion content varies seasonally.

[0046] Sea salt ion concentrations in snow samples from Zhongshan Station to Lambert Glacier in Antarctica decreased exponentially with increasing distance from the coast and / or altitude. Distance from the coast and / or altitude are two major factors influencing the spatial distribution of sea salt ions. High Cl and Na concentrations were observed in the steep coastal cliff area within a 20.6 km radius. + and Mg 2+ The concentration can be attributed to preferential wet or dry sedimentation of sea salt aerosols. The average Cl in the snow sample... - / Na + The ratio was 1.67 ± 0.44, indicating that the sea salt was distributed along the Cl band. - and Na + The main source. In aerosol sampling in Antarctica during 2010-2011, Na+ was visible in the aerosols. + Cl - The content of it is significantly higher.

[0047] 1.2 Establishment of a spectrum of environmental factors in polar low-temperature marine environments; 1.2.1 Establishment of a single-factor chronology for polar low-temperature marine environments; Based on relevant environmental data from publicly available databases, environmental factors at Zhongshan Station (coastal) and Vostok Station (inland, frigid zone) in Antarctica were statistically analyzed. Zhongshan Station is located on the Westoden Peninsula in the Larsmann Hills of Princess Elizabeth Land in East Antarctica, with geographical coordinates of 69°22′24″S, 76°22′40″E. The average annual temperature at Zhongshan Station over the past decade is -9.1℃, with an annual maximum of 9.6℃ and a minimum of -36.4℃. Overall, temperatures are low, with approximately 30 days of freeze-thaw cycles per year. The relative humidity near Zhongshan Station is generally low, with an annual average of 62.5%, classifying it as an arid climate. Zhongshan Station experiences polar day and polar night, with 54 consecutive days of daylight and 58 consecutive days of darkness. Over the past decade, Zhongshan Station has experienced an average of 123 days of snowfall per year, approximately one-third of the annual total. Vostok Station, located at 78°28′S, 106°48′E, near the Antarctic magnetic point, is the coldest place on Earth. August is the coldest month, with an average temperature as low as -68°C. On July 21, 1983, an extreme minimum temperature of -89.2°C was recorded, leading to this region being known as the "Cold Pole" of Antarctica. December is the hottest month, with an average temperature of -31.8°C and an extreme maximum temperature of -14.0°C (January 5, 1974). The annual average temperature is -55.2°C. It has a typical ice sheet climate typical of the Antarctic interior.

[0048] Based on the aforementioned polar environmental factor dataset, the intensity, duration, frequency, and temporal proportion of changes in environmental factors such as temperature, humidity, and snowfall were analyzed to form an annual spectrum for each individual environmental element. Temperature was divided into 11 intervals, each in 5°C increments: -40~-35°C, -35~-30°C, -30~-25°C, -25~-20°C, -20~-15°C, -15~-10°C, -10~-5°C, -5~0°C, 0~5°C, 5~10°C, and >10°C. Humidity was divided into 8 intervals, each in 10% increments: 20~30°C, 30~40°C, 40~50°C, 50~60°C, 60~70°C, 70~80°C, 80~90°C, and 90~100%. Snowfall spectrum was calculated based on the number of snowfall days within a specific temperature range, while the temperature-humidity spectrum combined temperature and humidity intervals for classification and calculation. Tables 1, 2, 3, and 4 are the annual chronologies of temperature, humidity, temperature-humidity, and diurnal temperature range at Zhongshan Station in Antarctica, respectively. Tables 5, 6, and 7 are the annual chronologies of temperature, humidity, and temperature-humidity at Vostok Station in Antarctica, respectively.

[0049] Table 1 Temperature Chronology of Zhongshan Station, Antarctica Table 2. Chronology of Relative Humidity at Zhongshan Station, Antarctica Table 3. Temperature-Humidity Chronology of Zhongshan Station, Antarctica Table 4. Diurnal Temperature Variation Spectrum at Zhongshan Station, Antarctica Table 5 Temperature Chronology of Vostok Station, Antarctica ; Table 6 Humidity Chronology of Vostok Station, Antarctica ; Table 7 Temperature-Humidity Chronology of Vostok Station, Antarctica ; 1.2.2 Establishment of a comprehensive chronology of factors affecting polar low-temperature marine environments; After collecting and statistically analyzing all environmental factors in the Antarctic and Arctic regions, and categorizing and calculating them to maximize coverage of the most extreme environments that metallic materials in polar regions might face, extreme values ​​of environmental factors from the three research stations over the past three years were selected to form data for Zhongshan Station and Vostok Station in Antarctica, as shown in Tables 8 and 9. This natural environment spectrum provides the temporal proportions of temperature and humidity, the number of days with snowfall, snow depth, cumulative duration and intensity of snow and ice cover, and Cl... - Na + and SO4 2- Information such as the concentration of the medium is included. Statistical data shows that the polar regions are constantly exposed to low temperatures and freezing conditions. The environmental chronology of Zhongshan Station will serve as the basis for establishing the environmental spectrum for indoor accelerated experiments.

[0050] Table 8 Chronology of Natural Environmental Factors at Zhongshan Station, Antarctica Table 9 Natural Environment Spectrum of Vostok Station, Antarctica This experiment primarily investigated environmental factors affecting material corrosion in polar environments, focusing on parameters such as temperature, humidity, snowfall, strong ultraviolet radiation, and salt deposition. The investigation revealed that the traditional TOW (time to wet) standard is insufficient for corrosion assessment in polar environments. The average annual relative humidity in polar environments is around 60%, and rising summer temperatures lead to the formation of a liquid film on metal surfaces, accompanied by freeze-thaw cycles, resulting in a significant corrosion process. High wind speeds cause snow redistribution and simultaneously bring marine aerosols to land, where they are deposited on metal surfaces via dry or wet deposition, creating electrolyte conditions.

[0051] Experiment 2: Establishment of accelerated environmental testing spectrum for multi-factor equivalent marine environment; The establishment of the multi-factor equivalent environmental accelerated test spectrum for marine environment was carried out in accordance with the following principles: Figure 3The approach is as follows: First, the principles for compiling the accelerated test spectrum are clarified. Based on the polar low-temperature marine environmental factor spectrum and the damage mechanism of composite materials, the key environmental factors affecting the service performance of composite materials are extracted, and corresponding test modules are designed. The experimental sequence, test parameters and values ​​are determined in sequence. Indoor tests are carried out according to the accelerated test spectrum, and the acceleration factor of the accelerated test spectrum is obtained by comparing and analyzing the results with those of outdoor tests.

[0052] 2.1 Screening and analysis of key environmental factors; To clarify the impact of environmental factors on the mechanical properties of composite materials, we conducted a grey relational analysis using the single-factor test results in Table 10 (some data came from the project team's previous data accumulation). Temperature, humidity, ultraviolet radiation, and time were used as comparison series, while tensile strength, tensile modulus, flexural strength, flexural modulus, impact strength, and compressive strength were selected as reference series.

[0053] Table 10 Results of Single-Factor Experiments 2.1.1 Mean normalization of data columns in grey relational analysis; Determine the reference series and comparison series. The main rows of the reference series are the factors, and the comparison series are the factors of each factor. Reference series: (1); (2); Compare sequences: (3); (4); (5); (6); Then, perform initialization processes separately: (7); (8); in, .

[0054] Since the magnitude and units of each environmental factor are different, these factor data columns need to be generated and processed, i.e., initialized, before performing grey relational analysis. For single-factor experimental test data, each item can be represented as: (9); Common initialization methods include initialization, minimumization, maximumization, averageization, and interval averaging. Initialization includes: (10); The single-factor test data series were averaged, and the averaged results are shown in Table 11.

[0055] Table 11 Averaged results of single-factor experiments 2.1.2 Grey relational coefficient analysis; After initialization, grey relational analysis can be used to analyze single-factor experimental data. Grey relational analysis essentially compares the degree of similarity between data and the geometric shape of the curve. Generally, the closer the geometric shapes, the closer the trends, and the greater the correlation. Therefore, when conducting correlation analysis, a reference sequence must first be determined, and then the similarity of other sequences to the reference sequence must be compared. Only in this way can the other sequences be compared and a judgment made. The steps for calculating the grey relational degree in grey relational analysis are: determine the comparison sequence and the reference sequence → calculate the correlation coefficient → calculate the correlation degree → sort the correlation degrees by magnitude.

[0056] set up: For reference sequence; ( Let be a sequence for comparison. Then we have the following definition: and The correlation coefficient is: (11); If remember ,but: (12); In the formula, For reference sequence Comparison of sequences exist The correlation coefficient at any given time. The resolution coefficient is 0 < <1, The specific value can be determined depending on the specific situation, but it is generally taken as 0.5. Called the first time, and absolute difference This is called the two-level minimum difference, where It is the first-order minimum difference, which means that in On the curve, the corresponding points and The minimum distance between the corresponding points in the middle. This means finding the minimum difference among the curves. On the basis of, then according to Find the minimum difference among all the curves with the minimum difference.

[0057] The maximum difference between the two levels has the same meaning as... The two-level minimum difference is similar. Therefore, the formula can be used to calculate... and corresponding Correlation coefficient between them: (13); 2.1.3 Calculation of Grey Relational Degree The calculation results of the correlation coefficients mainly yield numerical values ​​of the correlation between each comparison series and the reference series at various points. These results are numerous, and the information is too scattered, making comparison inconvenient. Therefore, it is necessary to concentrate the correlation coefficients of each comparison series at each time point into a single value; this value is the grey relational degree. (Comparison Series) For the reference sequence Grey relational degree is denoted as Calculate the correlation degree for the reference sequence: (14); For the reference sequence Comparison of sequences Their correlation degrees are respectively , All sequences form an associative order. Sort them from largest to smallest to obtain a grey relational order. From this, we can determine the sequence with the highest associativity and membership degree. The highest sequence correlation is the highest. The smallest sequence has the smallest correlation. Generally speaking, when... A value >0.6 indicates that the sequence has a good correlation.

[0058] 2.1.4 Calculation of comprehensive grey relational degree (principal component analysis) To clarify the impact of environmental factors on the comprehensive mechanical properties of composite materials, principal component analysis (PCA) was used to reduce the dimensionality of tensile strength, tensile modulus, flexural strength, flexural modulus, impact strength, and compressive strength. The specific process is as follows: (1) Establish the original sequence matrix of the response target, where xi(j) is the corresponding mechanical performance test result: (15); (2) Establish the correlation coefficient matrix R (16); In the formula, cov ( x i ( j ),x i ( l ))for x i ( j ), x i ( l The covariance of σ. x i ( j )for x i ( j The standard deviation of ).

[0059] (3) Eigenvalues ​​and eigenvectors The eigenvalues ​​are obtained using the following characteristic equation: (17); In the formula I m These are the eigenvectors.

[0060] (4) Principal components and cumulative contribution rate The principal component contribution rate and cumulative contribution rate are calculated using the following equations: (18); (19); The KMO and Bartlett test results in Tables 12 and 13 show that tensile strength, tensile modulus, flexural strength, flexural modulus, impact strength, and compressive strength are strongly correlated (KMO > 0.6, significance < 0.05), and two principal components can be extracted from them. The weight values ​​of the two principal components are shown in Table 14.

[0061] Table 12 Results of KMO and Bartlett's Tests Table 13 Explanation of Total Variance Table 14 Principal Component Weights The results obtained by dimensionality reduction of the single-factor test results based on the above calculations are shown in Table 15.

[0062] Table 15 PCA dimensionality reduction processing of single-factor test results The grey correlation degree and ranking between environmental factors and the comprehensive mechanical properties of composite materials are calculated according to equations (11) to (14), as shown in Table 16, where temperature > humidity > time > ultraviolet irradiation.

[0063] Table 16 Grey Relationship and Ranking between Environmental Factors and Comprehensive Mechanical Properties of Composite Materials Analysis results show that temperature, humidity, exposure time, and ultraviolet irradiation have the highest correlation with the comprehensive mechanical properties of composite materials, in the following order: temperature > humidity > time > ultraviolet irradiation. Therefore, in the subsequent accelerated test spectrum design, the focus will be on the above-mentioned key factors and their coupling effects, and corresponding "moisture absorption module", "freeze-thaw cycle module", "low temperature freezing module" and "ultraviolet irradiation module" will be designed.

[0064] 2.2 Accelerated Test Spectrum Module Design Since ISO 9223's criteria for determining the conditions for atmospheric corrosion and aging are no longer applicable to polar environments, it is necessary to redefine the conditions for atmospheric corrosion and aging in polar environments. Based on the surface wetting time criteria and test methods for material corrosion and aging in cold climates proposed by King et al., days with temperature T > -10℃ and relative humidity RH > 50% are defined as humid air; days with temperature T ≤ -10℃ and relative humidity RH ≤ 50% are defined as low-temperature freezing processes.

[0065] Based on the conditions under which material corrosion and aging can occur, and the results of grey relational analysis, the above environmental factor spectrum was modified. The simplified treatment of different environmental factors is as follows: Humid air: A simulated accelerated corrosion test was conducted using a salt spray test. The time with relative humidity 40%≤RH<60% was recorded as 50%, 60%≤RH<80% as 70%, and 80%≤RH<100% as 90%. The temperature range -10≤T<-5℃ was recorded as -10℃, -5≤T<5℃ as 0℃, and 5≤T≤10℃ as 10℃. Freeze-thaw cycles: The accelerated process was completed by increasing the temperature difference. Based on the 3.5% seawater freezing point, the daily maximum temperature T was considered... max >0℃, daily minimum temperature T min Days with a temperature <-1.9℃ are considered freeze-thaw days. If these days are included in humid air, they are only counted as freeze-thaw days. Low-temperature freezing: Storage in a laboratory environment at -40℃, with temperatures T≤-10℃ and relative humidity RH<40%, is recorded as a low-temperature freezing process. The simplified environmental spectrum is shown in Table 17.

[0066] Table 17 Duration of Action under Different Environmental Conditions Based on material failure mechanisms and outdoor field exposure test results, the main environmental factors influencing the failure behavior of metallic materials include temperature, humidity, and ultraviolet radiation. Therefore, its accelerating environment spectrum consists of four blocks, such as... Figure 4 As shown, these are the UV test module, moisture absorption test module, medium and low temperature freeze-thaw cycle test module, and low temperature freezing test module.

[0067] 2.3 Determining the experimental sequence; Throughout a natural year, as the four seasons change, natural phenomena such as humid air, freeze-thaw cycles, and low-temperature freezing occur in sequence. In addition, considering the damp heat test to accelerate the freeze-thaw cycle test and the low-temperature freezing test, the test sequence determined in this experiment is: moisture absorption test → freeze-thaw cycle test → low-temperature freezing test → ultraviolet test cycle.

[0068] 2.4 Determination of the magnitude of the accelerated test spectrum (1) Determination of environmental stress level; ① Moisture Absorption Test: The temperature range of humid air in polar environments is typically -10℃ to 10℃. This temperature range generally does not cause oxidative aging of the composite matrix resin; its impact on the aging process of the composite material is mainly reflected in the influence of moisture absorption kinetics. Furthermore, below 0℃, ice forms on the surface of the composite material, reducing moisture diffusion kinetics and inhibiting the moisture absorption process; this is not considered in the equivalent calculation. Environmental survey results show that the maximum humidity at Zhongshan Station is 96%, and the highest temperature is 9.6℃. Based on the principle of acceleration of the test spectrum, without changing the failure mode of the composite material, heating and humidification are used to promote the moisture absorption process. Therefore, the temperature range for the moisture absorption process is determined to be 45~80℃, and the humidity range is 95~100%RH, resulting in the following three test schemes: Option 1: Experimental parameters: temperature 60℃, 5% NaCl solution; Option 2: Test parameters: Temperature 80℃, Humidity 95%; Option 3: Test parameters: temperature 45℃, humidity 95%.

[0069] ② Freeze-thaw cycle test; The expansion coefficients of fibers and resins differ significantly, generating alternating residual stress at the fiber / resin interface during freeze-thaw cycles, affecting the degradation behavior of the composite material. Environmental survey results show that the melting process mainly occurs at Zhongshan Station. The lowest temperature at Zhongshan Station is -36.4℃, rounded to -40℃, and the highest temperature is 9.6℃. Heating accelerates melting, rounded to 20℃. Therefore, the freeze-thaw cycle test mainly considers the number of freeze-thaw cycles in the polar environment. Tensile strength is selected as the index for equivalent conversion to determine the number of freeze-thaw cycle tests (-40℃~20℃). The test time is determined based on the actual time required for moisture to freeze and thaw at the set temperature. Thus, the parameters of the freeze-thaw cycle test module are as follows: The experiment was conducted in a salt spray-freeze-thaw coupled test chamber. The test parameters were: freezing temperature -40℃, thawing temperature 20℃, and medium 5% NaCl solution.

[0070] ③ Low-temperature freezing test; Low-temperature treatment can reduce the fluidity of the composite material's molecular chains and the intermolecular bonding force, causing the matrix to shrink and harden. Simultaneously, the significant difference in the expansion coefficients of fibers and resins easily leads to residual stress at the fiber / matrix interface, resulting in cracks and debonding, thus affecting the mechanical properties of the composite material. Environmental survey results show that freezing phenomena exist at both Zhongshan Station and Vostok Station in Antarctica. The lowest temperature at Zhongshan Station is -36.4℃, and the average annual temperature at Vostok Station is -69.6℃. Therefore, -70℃ is chosen to fully reflect the effects of low temperature, resulting in the following parameters for the low-temperature freezing test module. The test was conducted in an ultra-low temperature freezing chamber with the following parameters: -70℃.

[0071] ④ Ultraviolet test; referring to the national standard GB / T 16422.3-2022, the irradiance intensity was selected as 0.76 W·m. -2 ·nm -1 The UV lamp was used for the experiment, and the UV exposure time depended on the UV radiation intensity (W) on the surface of the test piece in the UV test chamber and the amount of UV radiation received in one exposure cycle in the real outdoor environment (QT / MJ·m). -2 Therefore, the parameters of the ultraviolet test module are as follows: The experiment was conducted in an ultraviolet irradiation chamber with the following parameters: 0.76 W·m 2 ·nm -1 .

[0072] (2) Determination of environmental stress exposure time; The environmental stress exposure time was mainly determined according to the principle of equal proportion. The ratio of exposure time for different test modules can be approximated as: moisture absorption time: freeze-thaw time: freezing time: UV time = 6:1:6:6. The base time was set to 24h. Considering the continuity of the freeze-thaw process, its proportion was increased to 12h. In addition, considering that UV irradiation mainly acts on the sample surface and has a small impact on the performance of composite materials, its time proportion was reduced from the perspective of accelerating test efficiency, and it was set to 12h. Finally, the test times for the four modules in a single cycle were determined as follows: moisture absorption test 24h; freeze-thaw test -40℃×3h+20℃×3h, repeated twice, totaling 12h; low temperature freezing 24h, UV aging 24h.

[0073] Experiment 3: Validation of the effectiveness of multi-factor equivalent environmental accelerated test spectrum for marine environment; 3.1 The attenuation law of mechanical properties of composite materials in equivalent accelerated tests; A composite material aging life model was constructed based on a semi-empirical formula for residual strength. Regression analysis was used to fit laboratory aging data at different times, obtaining the coefficients in the semi-empirical formula. G.M. Guniev et al. believed that reversible and irreversible property changes during the aging process of polymer-based composite materials have both positive (reinforcement process) and negative (damage process) effects on material properties. For thermosetting composite materials exposed to the environment under no-load conditions, if we assume that the reinforcement and damage processes are independent, the strength change caused by irreversibility is: (20); In the formula, η , β , λ and θ All are undetermined coefficients; S Aging of composite materials t The strength value after time; S0 is the initial strength value of the composite material.

[0074] Based on the above semi-empirical formula for residual strength, the test data at each time point are first processed separately to obtain the average aging strength at each time point. Then, the regression analysis method for the undetermined parameters in equation (20) is determined using the aging test data at each time point. The specific process is as follows: (twenty one); (twenty two); Substituting equations (21) and (22) into equation (20), we get (twenty three); set up( t i , S i ), i =1, 2, ..., n Given a set of aging test data, from equations (21) and (22), we get: (twenty four); (25); Find a set of data ( x i , y i , S i ), i=1,2,…, n .

[0075] (26); Find Q pairs respectively S 0、 η , β , λ and θ Taking the partial derivative of and setting it to 0, we get: Under constraints (27); Under the given conditions, we can solve for... Q Minimum parameter S 0、 η , β , λ and θ By substituting these values ​​into equation (20), the aging median curve equation can be obtained, and the mechanical property degradation law of the composite material can be obtained.

[0076] Tables 18, 19, and 20 show the tensile strength of composite material T700 after different aging cycle tests according to Scheme 1, Scheme 2, and Scheme 3.

[0077] Table 18 Tensile strength of composite material T700 after different aging cycles according to Scheme 1 Table 19 Tensile strength of composite material T700 after different aging cycles according to scheme 2 Table 20 Tensile strength of composite material T700 after different aging cycles according to scheme 3 Using formulas (20) to (27), the tensile strength of composite material T700 was fitted, and the median curve equation of the tensile strength of composite material T700 under three equivalent acceleration schemes was obtained as follows: S = 974.0229 + 13585.9855(1 - e -0.0201t )-10210.6038ln(1+0.0291t)(28); S = 974.6086 + 20716.9040(1 - e -0.0287t )-16152.5484ln(1+0.0388t)(29); S = 969.0252 + 6.5122(1 - e -0.004t )-749.7969ln(1+0.0092t)(30); Let t=12, then equations (28), (29) and (30) can be used to predict the residual tensile strength S accelerated by a multi-factor coupled environment in the laboratory for 12 cycles. 12The median lifetimes were 827.5, 838.5, and 819.2, respectively, with errors of 1.4%, 0.3%, and 0.8%. This shows that the median lifetime predicted by this method is in high agreement with the experimental results.

[0078] Figure 5 The figure shows the median tensile strength curves of composite material T700 after three equivalent accelerated tests. As can be seen from the figure, in Schemes 1 and 2, the tensile strength of composite material T700 decreased rapidly in the initial stage of the test, then entered a slow decline phase, and continued to decline rapidly in the final stage. In Scheme 3, however, the tensile strength of composite material T700 did not show a significant decrease in the initial stage of the test, but began to decline after a period of time. Comparing the environmental conditions of the three test schemes, it can be seen that the rapid decrease in the tensile strength of composite material T700 in the initial stage of Schemes 1 and 2 is likely due to the excessively rapid moisture absorption rate. In actual low-temperature marine environments, the moisture absorption rate of composite materials is relatively slow. Therefore, it can be concluded that the performance degradation pattern of composite material T700 obtained by Scheme 3 of the equivalent accelerated test is closer to that of the actual environment.

[0079] Tables 21, 22, and 23 show the tensile strength of composite material T800 after different aging cycle tests according to Scheme 1, Scheme 2, and Scheme 3.

[0080] Table 21 Tensile strength of composite material T800 after different aging cycles according to scheme 1 Table 22 Tensile strength of composite material T800 after different aging cycles according to Scheme 2 Table 23 Tensile strength of composite material T800 after different aging cycles according to scheme 3 The tensile strength of composite material T800 was fitted using formulas (20) to (27), as follows: Figure 6 As shown, the median tensile strength curve equations of composite material T800 under three equivalent acceleration schemes are obtained as follows: S=985.0780-23.0412ln(1+5.4110t)(31); S = 972.861 + 0.1(1 - e -0.1t )-100.000ln(1+0.116t)(32); S = 985.6879 + 2.4318(1 - e -1.9886t -15.286ln(1+10t)(33; Let t=12, then equations (31), (32) and (33) can be used to predict the 12-cycle accelerated residual tensile strength S under a multi-factor coupled environment in the laboratory. 12 The median lifetimes were 888.6, 885.7, and 914.8, respectively, with errors of 0.2%, 1.6%, and 0.5%. This shows that the median lifetimes predicted by this method are in high agreement with the experimental results.

[0081] 3.3 Acceleration Equivalent Analysis of Equivalent Acceleration Test This experiment uses the accelerated equivalence relationship of laboratory accelerated testing based on damage equivalence as the criterion, and takes the retention rate of mechanical properties of composite materials as a parameter, allowing for natural environmental aging time. T The retention rate of the mechanical properties of the composite material is D; the mechanical property decay curve of the composite material under laboratory simulation conditions is obtained by plotting the fitting formula (34), and then the test time when the retention rate of the mechanical properties of the composite material is D under laboratory simulation conditions is obtained. t Finally, the acceleration equivalent coefficient α for the laboratory accelerated test was obtained by comparing the indoor and outdoor test times: (34); (1) Outdoor natural environment test (Xiaoping Island): After a winter low-temperature marine environment test (180 days), the tensile strength of T700 composite material was 956.8 MPa, with a retention rate of 98.8%; after the marine environment multi-factor equivalent accelerated environmental test according to Scheme 3, when the strength retention rate of composite material T700 was 98.8%, the corresponding test period was 1.33, about 112 hours; the acceleration equivalent coefficient of Scheme 3 for T700 composite material was 38.6; (2) Outdoor natural environment test (Zhongshan Station, Antarctica): After the T800 composite material underwent the test at Zhongshan Station, Antarctica (365 days), its strength retention rate was 95.82%; when the strength retention rate of the T800 composite material was 95.82%, the corresponding test period was 1.625, approximately 136.5 hours; the acceleration equivalent coefficient of the T800 composite material was 64.1.

[0082] Therefore, by comparing the microscopic damage characteristics and fracture morphology of composite material T700 under indoor equivalent accelerated testing and natural environment testing, it was clarified that the damage mode of composite material T700 under the three schemes of equivalent accelerated testing is consistent with the low-temperature marine environment. The attenuation law of tensile strength of composite materials T700 and T800 in the three schemes of equivalent accelerated testing was obtained by fitting the semi-empirical formula of residual strength. Among them, the change of tensile strength of T700 and T800 in the initial stage of the test of scheme 3 is not obvious, which is more similar to the natural environment. Using the damage equivalence criterion, the accelerated equivalent of scheme 3 on the attenuation of tensile strength of T700 and T800 is calculated to be 38.6 and 31.7, respectively.

[0083] Experiment 4: Construction of a high-throughput equivalent accelerated experimental method for multi-field coupled low-temperature environments; 4.1 Tension-bending loading fixture; Design as Figure 7 The tensile-bending loading fixture shown below is based on the three-point bending fixture. It fixes two sections of the sample and controls the degree of bending by adjusting the bolt elongation. Because the two sections of the sample are fixed, the sample bends while simultaneously being subjected to tensile forces from the two clamping ends. In summary, the tensile-bending loading fixture shown in the figure below allows for parallel testing of samples under bending and tensile loads, laying the foundation for coupling force loads with environmental loads.

[0084] 4.2 Equivalent accelerated test method for multi-field coupling of force load and environmental load; 4.2.1 Environmental load setting; The environmental loads were set according to the three marine environmental multi-factor equivalent accelerated environmental test spectra compiled in Experiment 3, which included four modules: endothermic test, freeze-thaw cycle test, low-temperature freezing test, and ultraviolet test, to simulate the multi-factor coupling effects of the low-temperature marine environment, such as... Figure 8 As shown.

[0085] 4.2.2 Force load setting; The loads that carbon fiber resin matrix composites bear during service are typically within the elastic range. When the bolt elongation is 0.8 mm, the bending deflection of the sample is 0.8 mm, and the tensile load is approximately 80 MPa, which is within the elastic range of the composite material. In summary, the force load is applied by controlling the bolt elongation, which is uniformly set to 0.8 ± 0.1 mm.

[0086] 4.3 High-throughput testing of the mechanical properties of micro-samples; 4.3.1 High-throughput analysis of microscopic damage in microsamples; Following accelerated environmental aging tests at different cycles based on the multi-factor equivalent environmental test spectrum of the marine environment, the characterization of high-throughput small samples was achieved using in-situ high-throughput field emission electron microscopy (Navigator-OPA) to acquire surface damage information, combined with CT to acquire internal layered damage information, and tensile testing using a multi-channel small sample tensile testing machine. Finally, the data acquired by each instrument were analyzed rapidly in high throughput using machine learning. The Navigator-OPA can achieve high-throughput continuous acquisition of tissue maps from multiple large-size samples, with an imaging speed approximately 50 times faster than traditional scanning electron microscopy for the same image quality. For the small samples in this experiment, the Navigator-OPA allows for simultaneous injection of multiple samples, significantly reducing the time consumed by frequent preparation work. Approximately 30,000 2048*2048 SEM images were acquired in this experiment. The trained intelligent detection model was used to process 28,252 surface field images to detect surface damage such as fiber breakage, cracks, and substrate detachment in the images in batches; 52,822 CT tomographic images were processed to detect layered damage features in the tomographic images in batches and to reconstruct them in 3D, with a processing speed of about 2 images / second.

[0087] 4.3.2 High-throughput testing of the mechanical properties of micro-samples; Following environmental aging tests at different cycles based on the multi-factor equivalent accelerated environmental test spectrum for marine environments, tensile testing was conducted on a high-throughput testing platform for the mechanical properties of micro-samples, in accordance with the GB / T 1447-2005 standard. The testing platform allows for the simultaneous testing of six micro-samples.

[0088] 4.4 Analysis of multi-field coupling effects of environmental-force loads; The strength retention rate of high-throughput micro specimens without accelerated aging and after undergoing different aging cycles in Scheme 1 was measured respectively. The test results are shown in Tables 24 and 25.

[0089] Table 24 Strength retention rate of high-throughput micro specimens after different aging cycles in Scheme 1 (applied load) Table 25 Strength retention rate of high-throughput micro specimens after different aging cycles in Scheme 1 (without applied load) To verify the experimental results, the median curve was fitted using the tensile strength data from Tables 24 and 25, and the equation of the median curve was obtained as follows: S=99.9692-9.7016ln(1+17.2405t)(35); S = 99.6572 + 2.8444(1 - e -0.1t)-7.0892ln(1+10.0t)(36); Let t=12, the strength retention rate S of the loaded specimen after 20 cycles of aging can be predicted by equations (35) and (36). 20 The strength retention rate S of the unloaded specimen after 10 cycles of aging was 48.2%. 10 It is 68.7%.

[0090] According to the data, the specimen under load was subjected to... 20 43.3% of the unloaded specimens 10 =68.2, then the relative error is: (37); (38); Therefore, the median lifetime predicted by this method is in high agreement with the experimental results.

[0091] Its curve is as follows Figure 9 and Figure 10 As shown, the tensile data obtained through laboratory simulation experiments are very close to the median curve fitted by the method in this section, with a high degree of overlap.

[0092] Comparing the mechanical property degradation curves of loaded and unloaded specimens, it can be seen that the degradation rate of the composite material's mechanical properties is significantly accelerated after applying a load. By comparing the strength retention rate S after 20 cycles of aging... 20 The promoting factor of the applied load on the decay law of the mechanical properties of composite materials is approximately 1.3.

[0093] Therefore, this experiment designed a tension-bending fixture to achieve the simultaneous application of tensile and bending loads. Furthermore, by combining the multi-factor equivalent environmental accelerated test spectrum of the marine environment, a high-throughput equivalent accelerated test method for low-temperature environment with multi-field coupling of "force load-environmental load" was constructed.

[0094] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention and within the spirit and principles of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for equivalent acceleration and lifetime prediction of composite materials under polar multi-field coupling environment, characterized in that, The method includes the following steps: S1. Construct the natural environment spectrum of the target service area, which includes time-varying data of at least two factors among temperature, humidity, ultraviolet radiation, salt spray and freeze-thaw cycles. S2. Based on the statistical analysis of the natural environment spectrum and the correlation analysis of environmental factors and material properties, key environmental factors are identified and corresponding accelerated test modules are designed and combined to form an accelerated test spectrum. S3. Based on the accelerated test spectrum, conduct multi-cycle accelerated aging tests on the composite material samples; S4. Test the mechanical properties of the composite material samples after aging and obtain performance degradation data; S5. Based on the equivalent relationship between performance degradation data and accelerated test spectrum, establish a life prediction model for composite materials to realize life prediction of composite materials under multi-field coupling environment. In step S5, the construction of the life prediction model for the composite material includes: Define a damage variable with the mechanical property retention rate as a metric. Based on accelerated aging test data, the law of change of damage variables with accelerated test time was obtained by fitting. By comparing the exposure time in the natural environment with the laboratory accelerated test time under the same damage variables, the accelerated equivalent coefficient is calculated, thereby establishing the equivalent relationship for life prediction. The residual strength empirical model used for fitting is: ； In the formula, Aging of composite materials Intensity value after time, This represents the initial strength value of the composite material. These are the model parameters determined by fitting experimental data. For time.

2. The method for equivalent acceleration and lifetime prediction of composite materials under polar multi-field coupling environment according to claim 1, characterized in that, In step S1, the natural environment spectrum of the target service area is constructed, including: Collect long-term meteorological and environmental pollutant data from representative stations in polar or low-temperature marine environments; Statistical analysis of meteorological and environmental pollutant data is conducted to form a comprehensive environmental factor spectrum that includes annual temperature, humidity, ultraviolet radiation, salt deposition, and freeze-thaw day-to-day data.

3. The method for equivalent acceleration and lifetime prediction of composite materials under polar multi-field coupling environment according to claim 1, characterized in that, In step S2, the accelerated test spectrum consists of at least three combinations of the following: moisture absorption module, freeze-thaw cycle module, low temperature freezing module, and ultraviolet irradiation module; the environmental stress level of each module is determined based on the extreme values ​​of the corresponding factors in the natural environment spectrum or the accelerated equivalence principle.

4. The method for equivalent acceleration and lifetime prediction of composite materials under polar multi-field coupling environment according to claim 3, characterized in that, The conditions for the moisture absorption module are: temperature 45°C to 80°C, relative humidity ≥95%, and / or carried out in a 5% NaCl solution; The conditions for the freeze-thaw cycle module are: temperature alternation between -40℃ and 20℃, with a 5% NaCl solution as the medium; The temperature of the low-temperature freezing module is ≤-40℃; The ultraviolet irradiation module uses an ultraviolet light source with a wavelength of 340nm.

5. The method for equivalent acceleration and lifetime prediction of composite materials under polar multi-field coupling environment according to claim 1, characterized in that, In step S3, while the composite material sample is subjected to accelerated aging test, a static or quasi-static tensile load and / or bending load is applied to the sample through a special loading fixture to achieve multi-field coupling accelerated test of force load and environmental load.

6. The method for equivalent acceleration and lifetime prediction of composite materials under polar multi-field coupling environment according to claim 1, characterized in that, In step S4, the mechanical properties of the aged specimen are tested using a high-throughput testing platform. This platform is capable of performing parallel mechanical tests on multiple micro specimens and / or using in-situ high-throughput characterization techniques to perform batch, rapid statistical analysis and identification of microscopic damage to the specimens.

7. A composite material equivalent acceleration and lifetime prediction system for polar multi-field coupling environments, characterized in that, This system is used to implement the equivalent acceleration and lifetime prediction method for composite materials under polar multi-field coupling environment as described in any one of claims 1-6, and the system comprises: The environmental spectrum construction and processing module is used to generate and process natural environmental spectra and accelerated test spectra. The key factor analysis module is used to perform statistical and correlation analysis on the natural environment spectrum to output key environmental factors; The multi-field coupled environment test chamber group includes at least a temperature and humidity control chamber, a freeze-thaw cycle chamber, an ultra-low temperature chamber, and an ultraviolet aging chamber, for performing the accelerated test spectrum; The mechanical property testing module is used to test the mechanical properties of aged samples. The data processing and life prediction module is used to process test data, run the life prediction model, and output the life prediction results of the composite material.

8. The equivalent acceleration and lifetime prediction system for composite materials under polar multi-field coupling environment according to claim 7, characterized in that, The system also includes: A multi-functional loading fixture is installed in a multi-field coupling environment test chamber to simultaneously apply set tensile and / or bending loads to multiple samples during accelerated aging. The central control unit is used to uniformly schedule and control the multi-field coupling environment test chamber, multi-functional loading fixtures and mechanical performance testing modules, and automatically execute the test process according to the preset test spectrum.

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