A Calendar Life Assessment Method for Multiple Stress Levels

Abstract

This invention discloses a calendar life assessment method for multiple stress levels, comprising: Step 1, determining the mission profile of airborne equipment and identifying the types of sensitive samples related to the calendar life of the airborne equipment; Step 2, determining the main stress types and stress levels of each sensitive sample; Step 3, determining the calendar life-stress acceleration model of each sensitive sample through laboratory tests; Step 4, determining the time proportion corresponding to each stress level of each sensitive sample under each stress type based on the mission profile; Step 5, calculating the calendar life of each sensitive sample under each stress level of each stress type based on the calendar life-stress acceleration model obtained in Step 3; Step 6, calculating the calendar life of each sensitive sample under each stress level of each stress type based on the calculation results of Steps 4 and 5 using a pre-designed calendar life prediction model for multiple stress levels. The technical solution provided by this invention solves the problem that the existing constant stress level assessment method for evaluating the calendar life of airborne equipment does not conform to the actual state of the airborne equipment, resulting in low reliability of the assessment conclusions.

Description

Technical Field

[0001] This invention relates to, but is not limited to, the field of life assessment technology, specifically a calendar life assessment method for multiple stress levels. Background Technology

[0002] Airborne equipment life indicators are essentially descriptions of product durability, primarily characterized by operational life and calendar life. During product development and qualification phases, it is necessary to verify and evaluate whether design specifications can be met in conjunction with specified mission profiles. Currently, methods for verifying and evaluating the operational life of airborne equipment are very mature and widely used in model development; however, methods for verifying and evaluating calendar life are relatively weak, still in the research and development stage, with few engineering application cases.

[0003] Considering that the calendar life of airborne equipment is generally very long, typically ranging from several decades, the stress levels it experiences throughout its lifespan vary significantly with seasons, day and night, region, and different operating conditions. Operating under multiple stress levels rather than a constant stress level is commonplace. Currently, life-stress acceleration models based on laboratory test results can calculate the calendar life of a product at a certain constant stress level. However, given that the calendar life-sensitive stresses (such as temperature) for most products, especially airborne equipment, are variable rather than constant throughout their entire lifespan, using current constant stress levels to assess the calendar life of airborne equipment does not reflect the actual conditions of airborne equipment, resulting in low reliability of the assessment conclusions. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned technical problems. This invention provides a calendar life assessment method for multiple stress levels, which solves the problem that existing constant stress level assessment methods for evaluating the calendar life of airborne equipment do not accurately reflect the actual condition of the equipment, leading to low reliability of the assessment conclusions.

[0005] The technical solution of the present invention: Embodiments of the present invention provide a calendar life assessment method for multiple stress levels, comprising:

[0006] Step 1: Determine the mission profile of the airborne equipment and identify the types of sensitive samples related to the calendar life of the airborne equipment;

[0007] Step 2: Determine the main stress types and stress levels of each sensitive sample.

[0008] Step 3: Determine the time percentage of each sensitive sample under each stress level for each stress type based on the task profile.

[0009] Step 4: Based on the type of sensitive sample, determine the calendar lifetime-stress acceleration model for each sensitive sample through laboratory testing.

[0010] Step 5: Based on the calendar lifetime-stress acceleration model of each sensitive sample obtained in Step 4, calculate the calendar lifetime of each sensitive sample at each stress level under each stress type.

[0011] Step 6: Based on the calculation results of Step 4 and Step 5, calculate the calendar lifetime of each sensitive sample using a pre-designed calendar lifetime prediction model for multiple stress levels.

[0012] Optionally, in the calendar life assessment method for multiple stress levels as described above, step 3 includes:

[0013] Based on the task profile, determine the stress level of each sensitive sample under each stress type, and obtain the time percentage corresponding to each stress level of each sensitive sample under each stress type.

[0014] Optionally, in the calendar life assessment method for multiple stress levels as described above, step 4 includes:

[0015] The calendar life-stress acceleration model type is selected based on the type of each sensitive sample. For each sensitive sample, the model parameters of the calendar life-stress acceleration model are confirmed by laboratory test regression, thus obtaining the calendar life-stress acceleration model for each sensitive sample.

[0016] Optionally, in the calendar life assessment method for multiple stress levels as described above, step 5 includes:

[0017] For each sensitive sample, the stress levels of each stress type are substituted into its respective calendar lifetime-stress acceleration model to calculate the calendar lifetime corresponding to each stress level in each stress type for each sensitive sample.

[0018] Optionally, in the calendar life assessment method for multiple stress levels as described above, before step 1, the method further includes:

[0019] Step a: Establish a calendar lifetime prediction model. The calendar lifetime prediction model takes the calendar lifetime corresponding to all stress levels of all stress types of all sensitive samples as input and the calendar lifetime of the sensitive samples as output.

[0020] Optionally, in the calendar life assessment method for multiple stress levels as described above, step a, establishing a calendar life prediction model, includes:

[0021] Based on the life-end mechanism of airborne equipment, and according to the weighted relationship between calendar life and calendar life of sensitive samples under various stress levels for different stress types, a calendar life prediction model is established as follows:

[0022]

[0023] Where t is the calendar lifetime of the sensitive sample;

[0024] The time percentage of the k-th stress level for the i-th stress type is determined by the task profile.

[0025] S l，k For the i-th stress type, the k-th stress level;

[0026] N represents the number of stress types in the sensitive sample;

[0027] i is 1, 2, 3, ..., N;

[0028] M represents the number of stress levels for the i-th stress type;

[0029] k is 1, 2, 3, ..., M;

[0030] f(S l，k ) represents the calendar lifetime of the sensitive sample at the k-th stress level for the i-th stress type, calculated by the calendar lifetime-stress acceleration model.

[0031] Optionally, in the calendar life assessment method for multiple stress levels as described above,

[0032] The stress types include: temperature, humidity, chemical substances, microorganisms, deformation, and load;

[0033] The stress level for each stress type is based on all values ​​from the airborne equipment mission profile.

[0034] Optionally, in the calendar life assessment method for multiple stress levels as described above,

[0035] The set of stress levels formed by the stress type and stress level is represented as follows:

[0036]

[0037] The calendar lifetime for each stress level under each stress type is:

[0038]

[0039] The time percentage for each stress level under each stress type is as follows:

[0040] in

[0041] The beneficial effects of this invention are as follows: This invention provides a calendar life assessment method for multiple stress levels. On one hand, by identifying the types of sensitive samples related to the calendar life of airborne equipment and determining the calendar life-stress acceleration model for each sensitive sample, the calendar life of each sensitive sample at each stress level under each stress type is calculated. On the other hand, by determining the main stress types and stress levels experienced by each sensitive sample and determining the time percentage of each sensitive sample at each stress level under each stress type based on the mission profile, the calendar life of each sensitive sample is calculated using a pre-designed calendar life prediction model for multiple stress levels based on the above two calculation results. The technical solution provided by this invention has the following beneficial effects:

[0042] 1) It expands the application scope of the life-stress acceleration model based on laboratory test data, breaks through the limitations of the traditional life calculation method with constant stress level, makes the evaluation conclusions more consistent with the actual service scenarios of the product, and improves the credibility of the conclusions.

[0043] 2) A calendar life assessment scheme for multiple stress levels is presented, the elements and steps of calendar life assessment are standardized, and the operability of the calendar life calculation method for multiple stress levels is improved.

[0044] 3) Based on the principle of weighting proportion, a cumulative damage modeling scheme is proposed, which provides a new idea and statistical analysis method for the collection and analysis of environmental stress levels during the service life of airborne equipment, and promotes the equipment environmental engineering profession to better serve model engineering. Attached Figure Description

[0045] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of the present invention and do not constitute a limitation on the technical solutions of the present invention.

[0046] Figure 1 A flowchart of a calendar life assessment method for multiple stress levels is provided as an embodiment of the present invention;

[0047] Figure 2 A trend graph of the life curve in a calendar life assessment method for multiple stress levels provided as an example of an implementation of the present invention. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

[0049] As explained in the background section, the lifespan of airborne equipment is typically characterized by operational lifespan and calendar lifespan. While methods for verifying and evaluating the operational lifespan of airborne equipment are well-established, methods for verifying and evaluating calendar lifespan are relatively weak and still in the research and development stage. These mainly include:

[0050] 1) The evaluation was based on the lifespan of calendar-sensitive components (mainly including seals, cables, springs, etc.) selected for airborne equipment. The evaluation value directly adopted the lifespan of the calendar-sensitive components without fully considering factors such as assembly dimensions, installation environment, and stress levels (temperature, humidity, chemicals, microorganisms, deformation, load, etc.).

[0051] 2) Using calendar life-sensitive samples as test objects, the tooling fixtures are designed to fit the actual working conditions of the aircraft as much as possible. Stress acceleration tests are carried out, and the test process data is used to establish a life-stress acceleration model. Then, the life under actual stress conditions is inferred. The evaluation value obtained based on the life-stress acceleration model is the life index of airborne equipment under constant stress. This causes the life assessment conclusion to deviate from the actual service life value of the equipment. The credibility of the assessment conclusion is poor and cannot support actual engineering applications.

[0052] Based on laboratory test data, a calendar life-stress acceleration model can be established for airborne equipment. The calendar life at a specified stress level S can then be calculated using this acceleration model. Typically, during a product's service life, it may encounter one or more stress levels, including temperature, humidity, chemicals, microorganisms, deformation, and load. Furthermore, each stress level may vary with environmental factors, seasons, and operating conditions, and is not a constant stress S. Currently, there is a lack of calendar life assessment models and standardized assessment procedures for multiple stress levels. Using a constant stress level to assess a product's calendar life does not reflect its actual condition, resulting in low reliability of the assessment conclusions.

[0053] Based on the above analysis, it is necessary and of great practical significance to establish a calendar life assessment method oriented towards multiple stress levels rather than constant stress levels. To address the aforementioned problems and the need for calendar life assessment at multiple stress levels rather than constant stress levels, this invention provides a calendar life assessment method oriented towards multiple stress levels.

[0054] The present invention provides the following specific embodiments, which can be combined with each other. For the same or similar concepts or processes, they may not be described again in some embodiments.

[0055] This invention provides a calendar life assessment method for multiple stress levels, applicable to both single stress types with different stress levels and multiple stress types with multiple stress levels. The technical solution provided by this invention mainly involves two parts: a calendar life assessment model and a flowchart for the calendar life assessment method.

[0056] The input to the calendar life assessment model is the calendar life corresponding to all stress levels for all stress types of each sensitive specimen. Stress types mainly include temperature, humidity, chemical substances, microorganisms, deformation, and load, and are determined by the wear and degradation mechanism, working environment, and operating conditions of the calendar life sensitive specimen. The stress level set S... N×M This represents all stress levels for all stress types, and the calendar life f(s) for each stress level under each stress type. N×M Time percentage (in ).

[0057] Among them, stress level set S N×M The proportion of each stress level under each stress type (in The calendar lifetime value f(S) for each stress level under each stress type is determined by the corresponding airborne mission profile. N×M The solution is obtained using a calendar life-stress acceleration model. The calendar life-stress acceleration models for calendar life-sensitive components such as seals, cables, and springs can all be constructed using existing mature methods; for example, the Arrhenius model is used for seals. Detailed input data for the calendar life assessment model is shown in Table 1.

[0058] Table 1 Inputs to the calendar life prediction model for multiple stress levels

[0059]

[0060]

[0061] The calendar life assessment method for multiple stress levels provided by this invention will be described in two parts below.

[0062] (I) Establishing a calendar life prediction model

[0063] First, given that calendar life loss is cumulative, the calendar life is considered to have reached its end when the total loss of calendar life due to each stress level of all stress types reaches the total calendar life (100%).

[0064] Secondly, based on the life-end mechanism of airborne equipment, and considering the weighted relationship between calendar life and calendar life of sensitive samples under various stress levels and stress types, a calendar life prediction model is established as shown in the following formula (1):

[0065]

[0066] Where t is the calendar lifetime of the sensitive sample;

[0067] The time percentage of the k-th stress level for the i-th stress type is determined by the task profile.

[0068] S i，k For the i-th stress type, the k-th stress level;

[0069] N represents the number of stress types in the sensitive sample;

[0070] i is 1, 2, 3, ..., N;

[0071] M represents the number of stress levels for the i-th stress type;

[0072] k is 1, 2, 3, ..., M;

[0073] f(S i，k ) represents the calendar lifetime of the sensitive sample at the k-th stress level for the i-th stress type, calculated by the calendar lifetime-stress acceleration model;

[0074] Finally, by transforming formula (1), we can obtain the formula for calculating the calendar lifetime of the sensitive sample, as shown in formula (2):

[0075]

[0076] (II) Implementation process of calendar life assessment method for multiple stress levels:

[0077] like Figure 1 The diagram shows a flowchart of a calendar life assessment method for multiple stress levels provided by an embodiment of the present invention. It includes the following steps:

[0078] Step 1: Determine the mission profile of the airborne equipment and identify the types of sensitive samples related to the calendar life of the airborne equipment;

[0079] In this step, the mission profile of the airborne equipment is determined based on its design, operational characteristics, and service characteristics.

[0080] Step 2: Determine the main stress types and stress levels of each sensitive sample.

[0081] In this step, the main stress types and stress levels under each stress type are determined based on the durability failure mechanism analysis.

[0082] Step 3: Determine the time percentage of each sensitive sample under each stress level for each stress type based on the task profile.

[0083] In this step, firstly, based on the task profile, the stress levels of each sensitive sample under each stress type are determined. Secondly, the time percentage corresponding to each stress level of each sensitive sample under each stress type is obtained.

[0084] Step 4: Determine the calendar lifetime-stress acceleration model for each sensitive sample through laboratory tests;

[0085] In this step, the calendar lifetime-stress acceleration model type is selected according to the type of each sensitive sample; for the calendar lifetime-stress acceleration model type selected for each sensitive sample, the model parameters of the calendar lifetime-stress acceleration model for each sensitive sample are confirmed by laboratory test regression, thus obtaining the calendar lifetime-stress acceleration model for each sensitive sample.

[0086] Step 5: Based on the calendar lifetime-stress acceleration model of each sensitive sample obtained in Step 4, calculate the calendar lifetime of each sensitive sample at each stress level under each stress type.

[0087] In step 5, for each sensitive sample, the stress level of each stress type is substituted into its respective calendar lifetime-stress acceleration model to calculate the calendar lifetime corresponding to each stress level in each stress type of each sensitive sample.

[0088] Step 6: Based on the calculation results of Step 4 and Step 5, calculate the calendar lifetime of each sensitive sample using a pre-designed calendar lifetime prediction model for multiple stress levels.

[0089] The calendar life assessment method for multiple stress levels provided in this invention, on the one hand, determines the types of sensitive samples related to the calendar life of airborne equipment and establishes a calendar life-stress acceleration model for each sensitive sample, thereby calculating the calendar life of each sensitive sample at each stress level under each stress type; on the other hand, it determines the main stress types and stress levels that each sensitive sample experiences, and determines the time percentage of each sensitive sample at each stress level under each stress type based on the mission profile; and then, based on the calculation results from the above two aspects, uses a pre-designed calendar life prediction model for multiple stress levels to calculate the calendar life of each sensitive sample. The technical solution provided in this invention has the following beneficial effects:

[0090] 1) It expands the application scope of the life-stress acceleration model based on laboratory test data, breaks through the limitations of the traditional life calculation method with constant stress level, makes the evaluation conclusions more consistent with the actual service scenarios of the product, and improves the credibility of the conclusions.

[0091] 2) A calendar life assessment scheme for multiple stress levels is presented, the elements and steps of calendar life assessment are standardized, and the operability of the calendar life calculation method for multiple stress levels is improved.

[0092] 3) Based on the principle of weighting proportion, a cumulative damage modeling scheme is proposed, which provides a new idea and statistical analysis method for the collection and analysis of environmental stress levels during the service life of airborne equipment, and promotes the equipment environmental engineering profession to better serve model engineering.

[0093] Implementation Example

[0094] The following uses the calendar life assessment of a certain airborne equipment as an example to explain in detail the implementation process of the calendar life assessment method for multiple stress levels provided by this invention. The assessment process is as follows: Figure 1 As shown. To clearly illustrate the implementation process of this example, the airborne equipment and its mission profile have been simplified. It is assumed that the calendar life sensitive component of the airborne equipment has only one O-ring seal, and the mission profile only considers the environment under day and night conditions throughout the year.

[0095] The first step is to determine the mission profile.

[0096] Airborne equipment will encounter various environmental conditions throughout its entire life cycle, including spring, summer, autumn, winter, day and night, and operating conditions.

[0097] The second step is to determine the stress type of sensitive samples related to the calendar life of airborne equipment.

[0098] In this embodiment, the sensitive sample was identified as an O-ring seal, and the main mechanism of calendar life wear of the O-ring seal was aging, with temperature as the stress type.

[0099] The third step is to determine the calendar lifetime-stress acceleration model based on experimental data.

[0100] 1) Determine the calendar lifetime-stress acceleration model

[0101] The O-ring calendar life-stress acceleration model is based on the Arrenius formula, the basic form of which is shown in formula (3):

[0102]

[0103] In the formula: F is the reaction rate, and its reciprocal can be used as a measure of the lifespan of airborne equipment;

[0104] P represents the state;

[0105] t represents time;

[0106] A is a constant variable, greater than 0;

[0107] K is the Boltzmann constant;

[0108] T represents absolute temperature, in degrees Celsius +273.

[0109] Ea is the activation energy, and the activation energy varies for different failure modes.

[0110] 2) Perform a linear transformation on the calendar lifetime-stress acceleration model.

[0111] To better utilize the Arrhenius model in engineering, a linear relationship between time and temperature needs to be established. The above equation can be transformed as follows:

[0112]

[0113] make:

[0114]

[0115] but:

[0116]

[0117] The standard format is as follows:

[0118] logt=a+b / T (5)

[0119] 3) Determine the model parameters of the calendar lifetime-stress acceleration model.

[0120] Assuming the laboratory selected four temperature levels—80℃, 120℃, 160℃, and 180℃—to conduct accelerated testing, the results are shown in Table 2.

[0121] Table 2. Test results at four different test temperatures.

[0122]

[0123]

[0124] The regression formula is logt = a + b / T, and the trend is as follows: Figure 2 The figure shown is a trend graph of the life curve in the calendar life assessment method for multiple stress levels provided in an embodiment of the present invention. The formula is as follows:

[0125] logt=6.3897+2170.60757 / T; (6)

[0126] The fourth step is to determine the time percentage for each sensitive sample at each stress level under each stress type.

[0127] The entire lifecycle of this airborne product includes seven usage scenarios: spring and autumn nighttime, spring and autumn nighttime, spring and autumn daytime, summer nighttime, summer daytime, winter nighttime, winter daytime, and during operation. The corresponding stress levels are 8℃, 18℃, 30℃, 35℃, -12℃, -2℃, and 180℃, with corresponding time percentages of 20%, 20%, 10%, 10%, 10%, 10%, and 20%, respectively. The temperature and stress levels and percentages throughout the product's lifecycle are shown in Table 3.

[0128] Table 3 Temperature and its stress level and proportion

[0129]

[0130]

[0131] The fifth step is to calculate the calendar lifetime of each sensitive sample at each stress level under each stress type.

[0132] Substituting the stress levels of each stress type in Table 3 into formula (6), the calendar life f(S) at stress levels of 8℃, 18℃, 30℃, 35℃, -12℃, -2℃, and 180℃ can be calculated respectively. i，k The calculation results are shown in Table 4.

[0133] Table 4 Calendar lifespan at various stress levels

[0134]

[0135] Step 6: Calculate the calendar lifetime of the sensitive sample using a calendar lifetime prediction model oriented towards multiple stress levels.

[0136] The calculation is performed according to formula (2), and the calculation results are shown in Table 5. Since the stress type of the O-ring in this example only includes temperature, there are a total of 7 stress levels, that is, N=1 and M=7 in formula (2).

[0137] Table 5 Life calculation under multiple stress levels

[0138]

[0139] The calculation results show that the calendar life of the airborne equipment under the multi-stress level service environment described in Table 3 is approximately 32.6 years (285637h).

[0140] The calendar life assessment method for multiple stress levels provided in this invention, on the one hand, determines the types of sensitive samples related to the calendar life of airborne equipment and establishes a calendar life-stress acceleration model for each sensitive sample, thereby calculating the calendar life of each sensitive sample at each stress level under each stress type; on the other hand, it determines the main stress types and stress levels that each sensitive sample experiences, and determines the time percentage of each sensitive sample at each stress level under each stress type based on the mission profile; and then, based on the calculation results from the above two aspects, uses a pre-designed calendar life prediction model for multiple stress levels to calculate the calendar life of each sensitive sample. The technical solution provided in this invention has the following beneficial effects:

[0141] 1) It expands the application scope of the life-stress acceleration model based on laboratory test data, breaks through the limitations of the traditional life calculation method with constant stress level, makes the evaluation conclusions more consistent with the actual service scenarios of the product, and improves the credibility of the conclusions.

[0142] 2) A calendar life assessment scheme for multiple stress levels is presented, the elements and steps of calendar life assessment are standardized, and the operability of the calendar life calculation method for multiple stress levels is improved.

[0143] 3) Based on the principle of weighting proportion, a cumulative damage modeling scheme is proposed, which provides a new idea and statistical analysis method for the collection and analysis of environmental stress levels during the service life of airborne equipment, and promotes the equipment environmental engineering profession to better serve model engineering.

[0144] While the embodiments disclosed in this invention are as described above, they are merely illustrative of the embodiments to facilitate understanding of the invention and are not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and variations in the form and details of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection for this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A calendar life assessment method for multiple stress levels, characterized in that, include: Step 1: Determine the mission profile of the airborne equipment and identify the types of sensitive samples related to the calendar life of the airborne equipment; Step 2: Determine the stress type and stress level of each sensitive sample; Step 3: Determine the time percentage of each sensitive sample under each stress level for each stress type based on the task profile. Step 4: Based on the type of sensitive sample, determine the calendar lifetime-stress acceleration model for each sensitive sample through laboratory testing. Step 5: Based on the calendar lifetime-stress acceleration model of each sensitive sample obtained in Step 4, calculate the calendar lifetime of each sensitive sample at each stress level under each stress type. Step 6: Based on the calculation results of Step 4 and Step 5, calculate the calendar lifetime of each sensitive sample using a pre-designed calendar lifetime prediction model for multiple stress levels. Before step 1, the following are also included: Step a, establish a calendar lifetime prediction model, which takes the calendar lifetime corresponding to all stress levels of all stress types of all sensitive samples as input and the calendar lifetime of the sensitive samples as output; Step a, establishing a calendar lifespan prediction model, includes: Based on the life-end mechanism of airborne equipment, and according to the weighted relationship between calendar life and calendar life of sensitive samples under various stress levels for different stress types, a calendar life prediction model is established as follows: ； Where t is the calendar lifetime of the sensitive sample; The time percentage of the k-th stress level for the i-th stress type is determined by the task profile. For the i-th stress type, the k-th stress level; N represents the number of stress types in the sensitive sample; i is 1, 2, 3, ..., N; M represents the number of stress levels for the i-th stress type; k is 1, 2, 3, ..., M; The calendar lifetime of the sensitive sample at the k-th stress level for the i-th stress type is calculated by the calendar lifetime-stress acceleration model.

2. The calendar life assessment method for multiple stress levels according to claim 1, characterized in that, Step 3 includes: Based on the task profile, determine the stress level of each sensitive sample under each stress type, and obtain the time percentage corresponding to each stress level of each sensitive sample under each stress type.

3. The calendar life assessment method for multiple stress levels according to claim 2, characterized in that, Step 4 includes: The calendar life-stress acceleration model type is selected based on the type of each sensitive sample. For each sensitive sample, the model parameters of the calendar life-stress acceleration model are confirmed by laboratory test regression, thus obtaining the calendar life-stress acceleration model for each sensitive sample.

4. The calendar life assessment method for multiple stress levels according to claim 3, characterized in that, Step 5 includes: For each sensitive sample, the stress levels of each stress type are substituted into its respective calendar lifetime-stress acceleration model to calculate the calendar lifetime corresponding to each stress level in each stress type for each sensitive sample.

5. The calendar life assessment method for multiple stress levels according to any one of claims 1 to 4, characterized in that, The stress types include: temperature, humidity, chemical substances, microorganisms, deformation, and load; The stress level for each stress type is based on all values ​​from the airborne equipment mission profile.

6. The calendar life assessment method for multiple stress levels according to claim 5, characterized in that, The set of stress levels formed by the stress type and stress level is represented as follows: ； The calendar lifetime for each stress level under each stress type is: ； The time percentage for each stress level under each stress type is as follows: ;in, .

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