Method for evaluating comprehensive service performance of insulating resin under irradiation

Abstract

The application discloses a kind of methods for evaluating the comprehensive service performance of insulating resin irradiation.It is simulated to detect step by ladder cumulative irradiation: set up multiple gradient cumulative irradiation dose for insulating resin sample, set up irradiation rate control group to carry out continuous gamma ray irradiation test, and the performance parameters of three dimensions of electrical insulation, thermal stability and mechanical mechanics are collected synchronously at multiple cumulative irradiation dose nodes; the step of establishing a comprehensive irradiation degradation quantitative evaluation model: establish a sub-item degradation normalization calculation model including electrical insulation irradiation, thermal stability irradiation and mechanical mechanics irradiation; and introduce weight coefficient, multi-parameter coupling correction coefficient and non-synchronous degradation correction coefficient to construct a comprehensive irradiation degradation evaluation model; comprehensive irradiation degradation quantitative evaluation: the performance parameters of each irradiation dose node are substituted into the evaluation model to complete the quantitative evaluation and screening of insulating resin radiation resistance performance.

Description

Technical Field

[0001] This invention relates to a method for evaluating the comprehensive service performance of insulating resin under irradiation, belonging to the field of resin performance testing technology. Background Technology

[0002] Insulating resins are commonly used to isolate different electrical components in electrical equipment to ensure their long-term stable operation under high-voltage environments. Depending on the characteristics of the working environment, the insulating materials in the equipment may be subjected to partial discharge and other effects, generating ionizing radiation (such as gamma rays and neutrons), affecting their overall service performance. Irradiation can cause epoxy resin molecular chains to break, cross-linked structures to degrade, or chemical bonds to change, leading to material aging. This can result in decreased insulation performance and reduced mechanical strength, making electrical equipment more susceptible to insulation failure, performance degradation, or insufficient sealing in irradiated fields, severely impacting the long-term reliability and safety of the equipment. Therefore, accurately assessing the radiation resistance of insulating resins is crucial for the long-term stable operation of different electronic components within electrical equipment under high-voltage environments.

[0003] Current conventional methods for evaluating the radiation resistance of insulating resins often employ single or a few performance indicators, and these tests lack systematic correlation. Existing methods are often limited to isolated parameters such as weight changes and decomposition behavior after irradiation, and measuring electrical insulation properties before and after irradiation at room temperature, failing to reveal the comprehensive performance evolution of insulating materials under continuous irradiation conditions. The dielectric and mechanical properties of insulating materials under irradiation differ significantly from those before irradiation, making it difficult to accurately assess their true service performance under actual irradiation conditions based solely on isolated indicators. Summary of the Invention

[0004] The purpose of this invention is to provide a method for evaluating the comprehensive service performance of insulating resins under irradiation, addressing the aforementioned problems. This method is of great significance for scientifically assessing the radiation resistance of materials, predicting the long-term reliability of materials in electrical equipment, and preventing related safety accidents, by evaluating the electrical, thermal, and mechanical service performance of insulating resins under simulated continuous irradiation environments.

[0005] The technical solution adopted in this invention is as follows: A method for evaluating the comprehensive service performance of insulating resin under irradiation, characterized by comprising a step A of stepped cumulative irradiation simulation detection, a step B of establishing a comprehensive irradiation degradation quantitative evaluation model, and a comprehensive irradiation degradation quantitative evaluation step C. Step A of the stepped cumulative irradiation simulation detection includes: A continuous gamma-ray irradiation test was conducted on the insulating resin sample with multiple gradient cumulative irradiation doses and an irradiation rate control group. The performance parameters of the sample in three dimensions—electrical insulation, thermal stability, and mechanical properties—were collected simultaneously at multiple cumulative irradiation dose nodes. Step B in establishing the comprehensive irradiation degradation quantitative assessment model includes: B1. Establish a normalized calculation model for the deterioration of electrical insulation by irradiation De, thermal stability by irradiation Dt, and mechanical deterioration by irradiation Dm. B2. Using the component-based degradation normalization calculation model of B1 and introducing the weight coefficient w, multi-parameter coupling correction coefficient α, and asynchronous degradation correction coefficient β, a comprehensive irradiation degradation degree D evaluation model is constructed. The comprehensive irradiation degradation quantitative assessment step C includes: Substitute the performance parameters of each irradiation dose node collected in step A into the evaluation model constructed in step B to complete the quantitative evaluation and screening of the radiation resistance performance of the insulating resin.

[0006] Alternatively, the irradiation test conditions for step A of the stepped cumulative irradiation simulation test are as follows: four groups of gradient cumulative irradiation doses are set: 0 Gy, 1.2 × 10^4 Gy, 1.2 × 10^5 Gy, and 1.2 × 10^6 Gy. The irradiation reference rate is 3.05 × 10^3 Gy / h. A control group with an irradiation rate of 4.07 × 10^3 Gy / h at a dose of 1.2 × 10^4 Gy is added. After each group of irradiation doses is completed, it serves as a sampling test node, and full-dimensional performance tests are carried out simultaneously.

[0007] Alternatively, the comprehensive irradiation degradation degree D assessment model is as follows:

[0008] In the formula, D: comprehensive irradiation degradation degree, dimensionless, with a value range of 0~1. The larger the value, the higher the degree of material irradiation aging and the greater the risk of insulation failure; De: electrical insulation irradiation degradation degree; Dt: thermal stability irradiation degradation degree; Dm: mechanical irradiation degradation degree. These are the weighting coefficients for electrical insulation, thermal stability, and mechanical properties, respectively, satisfying... α: Multi-parameter coupling correction coefficient, used to quantify the coupled aggravation effect of irradiation-induced internal molecular degradation and surface electrical property degradation; β: Asynchronous degradation correction coefficient, used to identify the latent aging characteristics of asynchronous decay of surface properties and internal micro-properties under irradiation.

[0009] The available weighting coefficients satisfy > > .

[0010] Alternatively, the multi-parameter coupling correction coefficient α can be calculated using the following formula:

[0011] Where: k is the coupling sensitivity coefficient; The value represents the correlation deviation of irradiation degradation in the three dimensions of electricity, heat and machinery. The larger the value, the more significant the damage caused by the combined aging of multiple performance components. The value range of α is [1, 1.6].

[0012] Alternatively, the asynchronous degradation correction coefficient β can be calculated as follows:

[0013] In the formula: Da is the average value of the three-dimensional irradiation degradation; the square root term is the standard deviation of the three-dimensional irradiation degradation data.

[0014] Optionally, the electrical insulation performance parameters include the breakdown field strength at 50 Hz, insulation resistance, dielectric constant at 50 Hz, and dielectric loss factor at 50 Hz. Formula for calculating the degree of electrical insulation degradation due to irradiation (De):

[0015] Eb0 and Ebt represent the breakdown field strength of the material before and after irradiation, respectively; R0 and Rt represent the insulation resistance before and after irradiation, respectively; ε0 and εt represent the dielectric constant at 50 Hz before and after irradiation, respectively; tanδ0 and tanδt represent the dielectric loss factor at 50 Hz before and after irradiation, respectively.

[0016] Alternatively, the thermal stability performance parameters may include initial thermal decomposition temperature, glass transition temperature, thermal weight loss rate, and thermal conductivity at room temperature of 25°C. Formula for calculating thermal stability irradiation degradation degree Dt:

[0017] Td0 and Tdt are the initial thermal decomposition temperatures before and after irradiation, respectively; Tg0 and Tgt are the glass transition temperatures before and after irradiation, respectively; W0 and Wt are the thermal weight loss rates before and after irradiation, respectively; λ0 and λt are the thermal conductivity at 25℃ before and after irradiation, respectively.

[0018] Alternatively, the mechanical performance parameters may include bending strength and tensile strength; Formula for calculating mechanical irradiation degradation degree Dm:

[0019] σb0 and σbt represent the bending strength before and after irradiation, respectively; σf0 and σft represent the tensile strength before and after irradiation, respectively.

[0020] Alternatively, step A may also include using scanning electron microscopy (SEM) to observe and obtain microscopic morphology data of the sample, which can be used to assist in verifying the evolution of microscopic defects such as molecular chain breakage, micropores, and microcracks inside the resin after irradiation, and simultaneously combining the macroscopic appearance morphology of the sample to complete the evaluation results for auxiliary verification and screening.

[0021] Alternatively, step C may also include classifying the material's irradiation aging level based on the comprehensive irradiation degradation degree D, to adapt to the life assessment and operation and maintenance management of equipment under irradiation conditions: 0≤D<0.2: No / slight irradiation aging, performance is intact; 0.2≤D<0.4: Slight degradation, can be used for a short period of time; 0.4≤D<0.6: Moderate degradation, monitoring needs to be strengthened; 0.6≤D<0.8: Severe degradation, with a high risk of breakdown / cracking; 0.8≤D≤1.0: Completely invalid, prohibited from use.

[0022] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. This invention provides a method for evaluating the comprehensive service performance of insulating resin under irradiation. It simultaneously measures multiple key parameters of the insulating resin under different irradiation environments, including electrical properties (such as breakdown field strength, dielectric constant, insulation resistance, and dielectric loss), thermal properties (such as thermogravimetric loss, initial decomposition temperature, and glass transition temperature), mechanical properties (such as flexural strength and tensile strength), and microstructure (SEM). This systematic and comprehensive evaluation overcomes the limitations of traditional single-index evaluation, enabling a scientific and comprehensive assessment of the radiation resistance of insulating materials. A unified quantitative evaluation model for the coupling of electro-thermal-mechanical multiple properties under irradiation is established. An irradiation coupling coefficient α and an asynchronous degradation coefficient β are introduced to accurately identify latent aging. A stepped irradiation dose is used to simulate real-world operating conditions, enabling full-process tracking of performance evolution. All parameters are derived from conventional testing and are readily applicable to engineering applications.

[0023] 2. The present invention provides a method for evaluating the comprehensive service performance of insulating resin under irradiation. Continuous irradiation experiments are conducted under different irradiation doses to simulate the irradiation effect under actual working conditions and reveal the evolution law of the material's comprehensive performance under different irradiation conditions. Attached Figure Description

[0024] Figure 1 These are the breakdown field strengths of 116HP resin under different irradiation doses.

[0025] Figure 2 This is a graph showing the dielectric constant of 116HP resin under different irradiation doses.

[0026] Figure 3 This is a dielectric loss diagram of 116HP resin under different irradiation doses.

[0027] Figure 4 This is a graph showing the insulation resistance of 116HP resin under different irradiation doses.

[0028] Figure 5 It is the flexural strength of 116HP resin under different irradiation doses.

[0029] Figure 6 It represents the tensile strength of 116HP resin after different cycles.

[0030] Figure 7 These are the initial thermal decomposition temperatures of 116HP resin under different irradiation doses.

[0031] Figure 8 This is a graph showing the thermal conductivity of 116HP resin under different irradiation doses.

[0032] Figure 9 These are the glass transition temperatures of 116HP resin under different irradiation doses. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings.

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0035] A method for evaluating the overall service performance of irradiated insulating resins. Step A: Stepped cumulative irradiation simulation detection procedure Five dry and clean samples were prepared using 116HP radiation-resistant insulating resin as the research object. Each sample was subjected to a total irradiation dose of 1.2 × 10⁴ Gy, 1.2 × 10⁵ Gy, and 1.2 × 10⁶ Gy, with a uniform irradiation rate of 3.05 × 10³ Gy / h. A control group with a varying irradiation rate of 4.07 × 10³ Gy / h was also added to the samples with a total irradiation dose of 1.2 × 10⁴ Gy. The samples with total irradiation doses of 0, 1.2 × 10⁴ Gy, 1.2 × 10⁵ Gy, and 1.2 × 10⁶ Gy were numbered 1, 2, 3, and 4, respectively, and the rate variation group with a total irradiation dose of 1.2 × 10⁴ Gy was numbered 5. The samples were evaluated using the following test methods, and the results are as follows: Figures 1-9 As shown.

[0036] Breakdown field strength test: The test was conducted according to standard GB / T1408.1-2006 (IEC60243-1:1998). The sample size was 40×40×0.5mm. Three clean and dry samples were prepared and tested under the same conditions. The sample was placed between two electrodes and immersed in insulating oil. A steady voltage increase of 1kV / s was then applied until the insulating sample broke down. The breakdown field strength was calculated as the ratio of the voltage at the moment of breakdown to the sample thickness. The average breakdown field strength of the three samples was taken as the typical breakdown field strength for this type of sample. After irradiation with a dose of 1.2×10⁴ Gy, the breakdown field strength of 116HP insulating resin decreased, and the decrease continued with increasing irradiation dose, with a greater decrease observed at an irradiation rate of 3.05×10³ Gy / h. This is because the stronger irradiation energy per unit time results in a more concentrated bombardment of epoxy polymer chains by high-energy particle streams such as gamma rays, generating a large number of free radicals. Consequently, fewer polymers undergo cross-linking reactions with the free radicals, ultimately leading to a higher defect density (such as micropores and cracks) within the material. These defects become charge concentration points, causing local electric field distortion, which significantly reduces the material's insulation performance and ultimately lowers the breakdown field strength.

[0037] Dielectric constant testing: A broadband dielectric spectrum / thermal stimulation current testing system, model GmbH, was used. The testing was conducted according to standard GB / T1409-2006. Six samples were prepared for testing. The samples were placed between electrodes (the effective area needed to be measured), and all parameters were set to form a capacitor, and its capacitance value was measured. The dielectric constant was obtained by multiplying the capacitance value by the ratio of the sample thickness to the vacuum dielectric constant. Simultaneously, the testing system measured the dielectric loss tangent. This yielded the variation of dielectric constant and dielectric loss with frequency. Dielectric constant at 50Hz power frequency: before irradiation: 3.4713, after irradiation: 4.4400, an increase of 27.91%; Dielectric loss at 50Hz power frequency: before irradiation: 0.0030, after irradiation: 0.0029, a decrease of 3.33%.

[0038] Insulation resistance test: Three samples were prepared for testing. The samples were placed between electrodes, and a test voltage was selected. Stable current values ​​were then recorded. The insulation resistance of the samples was obtained as the ratio of the test voltage to the current value, and the average resistance of the three samples was taken as the insulation resistance of this type of sample. The insulation resistance of the samples decreased after irradiation. This is because stronger irradiation intensity results in more high-energy particles bombarding the insulating material and exciting electron transitions, thus forming a large number of free electron-hole pairs and increasing carrier mobility. The surface trap energy levels deepen, accelerating the rate of charge trapping, thereby forming microscopic conductive regions locally within the material. Furthermore, a large number of free radicals recombine, forming a graphitization-like state, which increases conductivity. Therefore, the resistivity of the insulating material ultimately decreased by 2.97%.

[0039] Dielectric loss test: Six samples were prepared for testing using a dielectric loss tester. The samples were placed in the measuring chamber of the tester, ensuring good contact between the samples and the measuring electrodes. The test frequency and voltage were set. The current of the samples under AC voltage was measured, and the dielectric loss factor (tanδ) was calculated.

[0040] Scanning electron microscopy (SEM) testing: Observing the surface morphology and microstructure of the material. After irradiation with different doses, the SEM images of the samples did not show significant changes. This is because irradiation primarily damages the interior of the epoxy material, degrading the polymer crosslinking network (a large number of CH and C bonds are broken), but the surface damage is relatively low. Furthermore, SEM only represents the surface morphology and topology, and cannot represent changes at the molecular scale.

[0041] Flexural Strength Test: A flexural test was conducted on the composite material using the Sansi Measurement and Control System. Parameters such as the fracture flexural strength of the composite structure were determined according to the national standard GB / T9341-2008 "Determination of Flexural Properties of Plastics". Five samples were prepared for testing. After the first irradiation experiment, the flexural strength of the 116HP insulating resin decreased by 22.99%, and this decrease continued with increasing irradiation dose. This is because a large number of epoxy resin polymer chains degraded, reducing the maximum stress load that molecules could collectively bear. The resulting large number of free radicals cross-linked, forming a denser three-dimensional network structure, increasing the material's brittleness and making it difficult for the insulating material to withstand the higher energy generated by bending, ultimately reducing the flexural strength of the insulating material.

[0042] Bending strength calculation formula:

[0043] In the formula, F is the applied force, in Newtons. b and h are the width and thickness of the sample, respectively.

[0044] Tensile strength testing: This test determines the maximum load-bearing capacity of a material under tensile load, reflecting its ductility and toughness. At lower irradiation doses, specifically 12 kGy and 120 kGy, tensile strength decreases slightly, primarily due to molecular chain fragmentation induced by gamma rays, but the degree of fragmentation is low. At a dose of 1200 kGy, the decrease in tensile strength accelerates, reducing it by approximately 18%. At this level, the molecular chain fragmentation reaction intensifies, the cross-linked network degrades, and the weight-average molecular weight decreases, making it unable to withstand higher stress loads. Furthermore, numerous defects form within the material, causing stress concentration and becoming initiation points for microcracks, ultimately leading to a decrease in tensile strength.

[0045] Thermogravimetric analysis (TGA): This measure the mass change of a material during heating to determine its thermal stability and decomposition temperature. After the irradiation experiment, the macroscopic morphology of the sample did not change significantly. The weight loss rate of the sample increased after high-dose irradiation, and increased with increasing irradiation dose. This is because the chain-splitting reaction of the insulating resin molecular chains is intensified, the number of short branches increases, and more volatile small-molecule organic compounds are formed, leading to a further decrease in the initial thermal decomposition temperature. Figure 7 The initial thermal decomposition temperature of the sample can be obtained. After high-dose irradiation, the initial thermal decomposition temperature decreases, and this decrease continues with increasing irradiation dose. This is because irradiation degrades the epoxy polymer, forming volatile small molecule products, disrupting the chemical stability of the aromatic rings, and significantly reducing the material's thermal stability. Furthermore, the numerous free groups formed within the material due to irradiation actively break down the polymer chains due to increased temperature, decomposing them into even lower molecular weight products, ultimately leading to a decrease in the initial thermal decomposition temperature.

[0046] Thermal conductivity testing: The thermal conductivity of insulating resin irradiated with different doses at room temperature (25℃) was tested. The thermal conductivity decreased after irradiation, and this decrease continued with increasing irradiation dose. This is likely because gamma ray irradiation induces molecular chain breakage in the insulating resin (irradiation degradation), disrupting the phonon transport pathways along the molecular chains. Numerous defects within the material cause phonon scattering, and the recombination of numerous free radicals into smaller molecules further exacerbates the disorder within the material, leading to more severe scattering and ultimately a decrease in the thermal conductivity of the insulating material.

[0047] Differential Scanning Calorimetry (DSC): The glass transition temperature (GCT) curve shows that the GCT of the insulating resin increases after the first dose of irradiation. This is because radiation-induced degradation of the epoxy polymer generates a large number of free radicals. These free radicals recombine to form low-molecular-weight products, which then crosslink with the degraded molecular chains, forming a tighter three-dimensional network structure that restricts chain segment movement and increases the GCT. As the irradiation dose increases, the GCT gradually decreases. This is because the high energy of gamma rays may disrupt the CO backbone, causing a large number of long-chain polymers to be broken down into short-chain polymers. Furthermore, the disruption of the tight crosslinked network increases chain segment mobility, thereby lowering the GCT.

[0048] This invention addresses the typical characteristics of insulating resins under continuous gamma-ray irradiation, including molecular chain breakage, cross-linking degradation, defect proliferation, and synergistic deterioration of multiple properties, abandoning the isolated evaluation model based on a single indicator. It uses electrical insulation performance, thermal stability, and mechanical properties as three core dimensions, employs initial performance normalization to eliminate dimensional differences, and introduces an irradiation coupling correction coefficient α and an asynchronous degradation correction coefficient β to quantify the irradiation-induced "molecular damage → microscopic defects → macroscopic failure" chain mechanism. This accurately identifies the hidden risks of asynchronous performance degradation under irradiation, achieving a comprehensive, accurate, and quantitative evaluation of overall service performance.

[0049] Step B in establishing a comprehensive irradiation degradation quantitative assessment model: 1. Core Comprehensive Degradation Evaluation Model

[0050] In the formula: D : Overall deterioration degree, dimensionless, with a value range of 0 to 1. The larger the value, the more severe the material irradiation aging and the greater the risk of performance failure. De Electrical insulation degradation; Dt Thermal stability degradation; Dm Mechanical degradation degree; These are the weighting coefficients for electrical, thermal, and mechanical properties, respectively, satisfying... ; α : Multi-parameter coupling correction coefficient, used to quantify the coupled aggravating effect of internal degradation and surface / electrical aging; β : Asynchronous degradation correction coefficient, used to identify latent aging characteristics where surface properties and internal properties evolve asynchronously.

[0051] 2. Formula for calculating the degree of deterioration of each item The three core dimensions of basic aging damage are all calculated using initial performance benchmark normalization to eliminate differences in parameter dimensions: (1) Electrical insulation degradation :

[0052] 、 These represent the initial and post-irradiation breakdown field strengths of the material, respectively. , These are the initial and post-irradiation insulation resistances, respectively. , These are the initial and post-irradiation dielectric constants, respectively. , These represent the initial and post-irradiation dielectric losses, respectively.

[0053] (2) Deterioration of thermal stability :

[0054] , These are the initial and post-irradiation thermal decomposition temperatures, respectively. , These are the initial and post-irradiation glass transition temperatures, respectively. , These represent the initial and post-irradiation thermogravimetric rates, respectively. , These are the initial and post-irradiation thermal conductivity values, respectively.

[0055] (3) Deterioration of mechanical properties :

[0056] , These represent the initial and post-cycle bending strengths, respectively. , These represent the initial tensile strength and the tensile strength after cyclic loading, respectively.

[0057] 3. Weighting coefficients Electrical safety failure > thermal aging structural failure > mechanical performance degradation This allocation method accurately reflects the actual service importance of insulating resins under irradiation conditions in nuclear power, aerospace, and high-energy physics equipment, making the comprehensive evaluation results more scientific and more aligned with engineering needs. Therefore, the following method is adopted: .

[0058] 4. Multi-parameter coupling correction coefficient

[0059]

[0060] in: The coupling sensitivity coefficient is uniformly set to 0.8 for electrical insulation materials; This represents the deviation between internal and external aging; the larger the value, the stronger the parameter coupling effect and the more significant the cumulative damage from aging. Value range: When there is no coupling deviation The coefficient increases as coupling aging intensifies.

[0061] 5. Asynchronous aging correction factor

[0062] The core innovation coefficient of the formula is specifically designed to identify asynchronous aging characteristics mentioned in the text (surface qualified but internally deteriorated, internally intact but surface collapsed), solving the problems of missed early aging and lifespan prediction errors.

[0063] To eliminate errors from manual experience-based value selection and achieve full-parameter quantitative calculation, a quantitative formula for the asynchronous aging correction coefficient β is constructed based on multi-dimensional aging deviation entropy values. This formula accurately characterizes the degree of imbalance in aging across three dimensions: mechanical properties, electrical insulation, and thermal stability. The judgment logic and calculation formula are as follows:

[0064] In the formula: The average value of the three-dimensional basic aging damage is given by the square root term, which represents the standard deviation of the three-dimensional aging data. This accurately reflects the discrete deviation of the aging degree in each dimension and perfectly matches the asynchronous aging characteristics of materials.

[0065] Coefficient value determination mechanism: During synchronous aging, the three-dimensional aging values ​​are basically consistent, and the standard deviation approaches 0. The greater the aging asynchrony, the larger the standard deviation. β The numerical values ​​increase synchronously, automatically amplifying the weight of latent aging damage, eliminating the need for manual grading and judgment, and achieving fully automated quantitative calculation.

[0066] Comprehensive Irradiation Degradation Quantitative Assessment Step C: The method of this invention was used to treat 116HP resin at a maximum dosage of 1.2 × 10⁻⁶. 6 Taking Gy experimental data as an example, the aging status evaluation is carried out, and the calculation process is as follows.

[0067] ① Electrical insulation degradation De =1 1 / 4(20.016 / 29.482+28.3 / 747+6.9630 / 15.4979+0.0785 / 0.2294)=0.227 ②Deterioration of thermal stability performance Dt =1 - 1 / 3(268.3 / 315.5 + 32.22 / 55.10 + 5.0452 / 3.2598) = 0.316 ③Deterioration of mechanical properties Dm =1 - 1 / 2(32.502 / 80.228 + 8.990 / 35.051) = 0.385 ④ Basis-weighted aging damage 0.45×0.227+0.35×0.316+0.20×0.385=0.291 ⑤ Multi-parameter coupling correction coefficient α=1+0.8×|0.316–√(0.227×0.385)|=1.104 ⑥ Asynchronous aging correction factor β=1.147 ⑦ Overall aging damage D =1.104 × 0.291 × 1.147 = 0.371 Based on the comprehensive aging damage degree D, the aging state of materials is classified to adapt to engineering life assessment and equipment operation and maintenance: (1) 0≤D<0.2: No / slight irradiation aging, performance is intact; (2) 0.2≤D<0.4: Slight degradation, can be used for a short period of time; (3) 0.4≤D<0.6: Moderate degradation, monitoring needs to be strengthened; (4) 0.6≤D<0.8: Severe degradation, with a high risk of breakdown / cracking; (5) 0.8≤D≤1.0: Completely invalid, prohibited from use.

[0068] D=0.371 indicates severe asynchronous aging. After 60 liquid nitrogen cycles, the material showed significant risks of low-temperature brittleness and insulation degradation, which is completely consistent with the experimental results.

[0069] In summary, the final result for 116HP resin was mild to moderate irradiation aging, which is completely consistent with the experimental test results. Therefore, by comprehensively measuring multi-dimensional performance parameters such as thermal, electrical, and mechanical properties, the accuracy of evaluating the radiation resistance of insulating resins can be improved, and the reliability of insulating resins under actual working conditions can be further understood.

[0070] Current evaluation methods often focus on single performance indicators, such as relying solely on breakdown field strength analysis to judge a material's radiation resistance, or measuring its electrical properties without considering actual radiation environments. Such isolated testing methods cannot comprehensively reflect the interactions and synergistic degradation mechanisms among various performance parameters of a material under irradiation conditions. Since there is an inherent correlation between the electrical, mechanical, and stability properties of insulating resins under irradiation, relying on a single indicator can easily lead to evaluation results deviating from reality. This patent employs a systematic multi-parameter comprehensive evaluation, its advancement lying in constructing a bridge from the radiation resistance performance of materials in simulated experiments to the evaluation of actual engineering reliability. By exposing materials to environments with different irradiation doses, experimental parameters are obtained, and the synergistic evolution of multi-dimensional properties such as electrical, thermal, and mechanical properties is comprehensively analyzed. For the first time, a dynamic correlation map between irradiation and performance is constructed. This technical evaluation system transforms engineering decision-making from an experience-based inference model to a data-driven, targeted approach. Before a material is put into service, its comprehensive performance synergistic degradation law under irradiation environments is predicted, effectively avoiding potential failure risks caused by improper selection of insulating materials. Furthermore, scientifically evaluating the remaining lifespan of in-service equipment provides managers with quantifiable failure warning thresholds for materials, ultimately ensuring the long-term operational reliability and safety of electrical equipment in actual irradiation environments.

[0071] Furthermore, the testing conditions used in existing experimental methods differ significantly from actual operating conditions. In electrical equipment, insulating materials are subjected to a combined environment of irradiation and electro-thermal stress for extended periods. Conventional room-temperature electrical performance tests or short-term irradiation tests are insufficient to effectively simulate such comprehensive stress conditions, leading to overly idealized evaluation results that fail to accurately predict the material's performance evolution and service life during long-term operation. This proposed solution effectively simulates the service environment of insulating resins in real equipment by setting up phased experiments under different irradiation doses. By combining multiple sampling and analysis during the process, it can systematically capture the changing trends of material properties with increasing irradiation dose (such as the gradual decrease in insulation resistance and the slow decay of tensile strength) and key inflection points (such as the rise and fall of glass transition temperature). This allows for a more accurate assessment of its durability and failure threshold under long-term irradiation conditions, providing a practical reference for engineering selection and service life prediction.

[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. The invention extends to any new features or combinations disclosed in this specification, and any modifications, equivalent substitutions, and improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the above exemplary embodiments, and that any detailed technical features not disclosed in these embodiments are prior art, which can be obtained by those skilled in the art from the prior art.

Claims

1. A method for evaluating the comprehensive service performance of irradiated insulating resin, characterized in that: It includes step A, which involves simulating and detecting stepped cumulative irradiation; step B, which involves establishing a comprehensive irradiation degradation quantitative assessment model; and step C, which involves comprehensive irradiation degradation quantitative assessment. Step A of the stepped cumulative irradiation simulation detection includes: A continuous gamma-ray irradiation test was conducted on the insulating resin sample with multiple gradient cumulative irradiation doses and an irradiation rate control group. The performance parameters of the sample in three dimensions—electrical insulation, thermal stability, and mechanical properties—were collected simultaneously at multiple cumulative irradiation dose nodes. Step B in establishing the comprehensive irradiation degradation quantitative assessment model includes: B1. Establish a normalized calculation model for the deterioration of electrical insulation by irradiation De, thermal stability by irradiation Dt, and mechanical deterioration by irradiation Dm. B2. Using the component-based degradation normalization calculation model of B1 and introducing the weight coefficient w, multi-parameter coupling correction coefficient α, and asynchronous degradation correction coefficient β, a comprehensive irradiation degradation degree D evaluation model is constructed. The comprehensive irradiation degradation quantitative assessment step C includes: Substitute the performance parameters of each irradiation dose node collected in step A into the evaluation model constructed in step B to complete the quantitative evaluation and screening of the radiation resistance performance of the insulating resin.

2. The method as described in claim 1, characterized in that: The irradiation test conditions for step A of the stepped cumulative irradiation simulation test are as follows: four groups of gradient cumulative irradiation doses are set: 0 Gy, 1.2 × 10^4 Gy, 1.2 × 10^5 Gy, and 1.2 × 10^6 Gy. The irradiation reference rate is 3.05 × 10^3 Gy / h. A control group with an irradiation rate of 4.07 × 10^3 Gy / h at a dose of 1.2 × 10^4 Gy is added. After each group of irradiation doses is completed, it serves as a sampling test node, and full-dimensional performance tests are carried out simultaneously.

3. The method as described in claim 1, characterized in that: The comprehensive irradiation degradation degree D assessment model is as follows: In the formula, D: comprehensive irradiation degradation degree, dimensionless, with a value range of 0~1. The larger the value, the higher the degree of material irradiation aging and the greater the risk of insulation failure. De: Electrical insulation degradation due to irradiation; Dt: Thermal stability degradation due to irradiation; Dm: Mechanical degradation due to irradiation; These are the weighting coefficients for electrical insulation, thermal stability, and mechanical properties, respectively, satisfying... ; α: Multi-parameter coupling correction coefficient, used to quantify the intensified coupling effect of irradiation-induced internal molecular degradation and surface electrical property degradation; β: Asynchronous degradation correction factor, used to identify the latent aging characteristics of asynchronous decay of surface properties and internal microstructure properties under irradiation.

4. The method as described in claim 3, characterized in that: The formula for calculating the multi-parameter coupling correction coefficient α is as follows: Where: k is the coupling sensitivity coefficient; The value represents the correlation deviation of irradiation degradation in the three dimensions of electricity, heat and machinery. The larger the value, the more significant the damage caused by the combined aging of multiple performance components. The value range of α is [1, 1.6].

5. The method as described in claim 3, characterized in that: The asynchronous degradation correction coefficient β is calculated as follows: In the formula: Da is the average value of the three-dimensional irradiation degradation; the square root term is the standard deviation of the three-dimensional irradiation degradation data.

6. The method as described in claim 3, characterized in that: The electrical insulation performance parameters include the breakdown field strength at 50 Hz, insulation resistance, dielectric constant at 50 Hz, and dielectric loss factor at 50 Hz. Formula for calculating the degree of electrical insulation degradation due to irradiation (De): Eb0 and Ebt represent the breakdown field strength of the material before and after irradiation, respectively; R0 and Rt represent the insulation resistance before and after irradiation, respectively; ε0 and εt represent the dielectric constant at 50 Hz before and after irradiation, respectively; tanδ0 and tanδt represent the dielectric loss factor at 50 Hz before and after irradiation, respectively.

7. The method as described in claim 3, characterized in that: The thermal stability performance parameters include initial thermal decomposition temperature, glass transition temperature, thermal weight loss rate, and thermal conductivity at room temperature of 25°C. Formula for calculating thermal stability irradiation degradation degree Dt: Td0 and Tdt are the initial thermal decomposition temperatures before and after irradiation, respectively; Tg0 and Tgt are the glass transition temperatures before and after irradiation, respectively; W0 and Wt are the thermal weight loss rates before and after irradiation, respectively; λ0 and λt are the thermal conductivity at 25℃ before and after irradiation, respectively.

8. The method as described in claim 3, characterized in that: The mechanical performance parameters include bending strength and tensile strength. Formula for calculating mechanical irradiation degradation degree Dm: σb0 and σbt represent the bending strength before and after irradiation, respectively; σf0 and σft represent the tensile strength before and after irradiation, respectively.

9. The method as described in claim 1, characterized in that: Step A also includes using scanning electron microscopy (SEM) to observe and obtain microscopic morphology data of the sample, which is used to assist in verifying the evolution of microscopic defects such as molecular chain breakage, micropores, and microcracks inside the resin after irradiation. The evaluation results are simultaneously verified and screened in conjunction with the macroscopic appearance of the sample.

10. Step C also includes classifying the material's irradiation aging level based on the comprehensive irradiation degradation degree D, adapting it to the life assessment and operation and maintenance management of equipment under irradiation conditions: 0≤D<0.2: No / slight irradiation aging, performance is intact; 0.2≤D<0.4: Slight degradation, can be used for a short period of time; 0.4≤D<0.6: Moderate degradation, monitoring needs to be strengthened; 0.6≤D<0.8: Severe degradation, with a high risk of breakdown / cracking; 0.8≤D≤1.0: Completely invalid, prohibited from use.

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