Equivalent simplification method of aircraft load spectrum

Abstract

The invention relates to an equivalent simplification method of an aircraft load spectrum, and relates to the technical field of aircrafts. The method comprises the following steps: acquiring an original multi-level load spectrum determined based on a multi-level load spectrum model corresponding to a full-size aircraft; performing simplification processing on the original multi-level load spectrum based on an equivalent damage rule to obtain a target multi-level load spectrum; wherein the number of first stress levels of the original multi-level load spectrum is greater than the number of second stress levels of the target level load spectrum; determining the original life distribution of the multi-level load spectrum model under the target level load spectrum; and converting the original life distribution to obtain target life distribution of the multi-level load spectrum model under the constant-amplitude load spectrum. According to the invention, the precision of the simplified load spectrum is improved.

Description

Background Art

[0002] The existing low-order load spectrum simplification method is: first, delete the load with low stress level; second, convert the damage caused by low load into the load with high stress level, so as to reduce the number of load cycles; however, this simplification method belongs to accelerated fatigue, and its difficulty lies in finding a definite method to make the statistical properties of the damage distribution caused by a loading block before and after simplification the same, that is, to ensure that the distribution of the number of blocks before and after conversion is the same when the structure reaches fatigue failure; and the fatigue life of the structure is the product of the number of loading blocks and the number of loading hours or the total number of cycles of a loading block. As the total number of cycles after simplification decreases, the corresponding life is shortened, so the accuracy of the simplified load spectrum is low.

[0003] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0004] The purpose of the present disclosure is to provide an equivalent simplified method for aircraft load spectrum, thereby overcoming the problem of low accuracy of simplified load spectrum caused by limitations and defects of related technologies at least to a certain extent.

[0005] According to one aspect of the present disclosure, an equivalent simplified method for aircraft load spectrum is provided, comprising:

[0006] Acquire an original multi-level load spectrum determined based on a multi-level load spectrum model corresponding to a full-scale aircraft;

[0007] The original multi-level load spectrum is simplified based on the equivalent damage rule to obtain a target multi-level load spectrum; wherein the number of first stress levels of the original multi-level load spectrum is greater than the number of second stress levels of the target multi-level load spectrum;

[0008] Determining the original life distribution of the multi-level load spectrum model under the target level load spectrum;

[0009] The original life distribution is transformed to obtain a target life distribution of the multi-level load spectrum model under a constant amplitude load spectrum.

[0010] In an exemplary embodiment of the present disclosure, the original multi-level load spectrum is simplified based on the equivalent damage rule to obtain a target multi-level load spectrum, including:

[0011] Calculating the cycle life ratio of each load spectrum of different levels in the original multi-level load spectrum, and truncating the original multi-level load spectrum based on the cycle life ratio to obtain a truncated multi-level load spectrum;

[0012] Calculate the fatigue damage of each load spectrum of different levels after truncation; wherein the multi-level load spectrum after truncation includes the first-level load spectrum, the second-level load spectrum, ..., the m+1-th level load spectrum, ..., the 2m+1-th level load spectrum; the fatigue damage includes the first-level fatigue damage, the second-level fatigue damage, ..., the m+1-th level fatigue damage, ..., the 2m+1-th level fatigue damage;

[0013] Calculating a first reference distribution of each load spectrum at different levels according to a first average value and a first standard deviation of the fatigue damage, and determining a target number of cycles of each load spectrum at different levels based on the first reference distribution;

[0014] The original cycle number of the truncated multi-level load spectrum is replaced based on the target cycle number to obtain the target multi-level load spectrum.

[0015] In an exemplary embodiment of the present disclosure, calculating fatigue damage of each load spectrum at different levels after truncation includes:

[0016]

[0017] Among them, D i is the fatigue damage of the load spectrum at level i, N ij and N i is the random fatigue life, E i is the expected fatigue life, n i is the original number of cycles of the load spectrum of the i-th level, i is the load level of the stress of the i-th level; a i is a fixed exponent, f i is the hysteresis effect coefficient, S i is the stress amplitude of the stress at the i-th level; is the maximum value of the load level from level 1 to the stress of level i-1; v is the material constant.

[0018] In an exemplary embodiment of the present disclosure, calculating the first reference distribution of the load spectrum of each different level according to the first average value and the first standard deviation of the fatigue damage includes:

[0019] Extracting the m+1th level fatigue damage and the 2m+1th level fatigue damage from the fatigue damage, and calculating a first average value and a first standard deviation of the m+1th level fatigue damage and the 2m+1th level fatigue damage based on a maximum likelihood estimation method;

[0020] A first reference distribution of the (m+1)th level load spectrum and the (2m+1)th level load spectrum is determined based on the first average value and the first standard deviation.

[0021] In an exemplary embodiment of the present disclosure, determining the target number of cycles of each load spectrum at different levels based on the first reference distribution includes:

[0022] Taking the first reference distribution as a benchmark and taking the equivalent damage distribution corresponding to the target number of cycles as a constraint condition that the equivalent damage distribution corresponding to the target number of cycles is infinitely close to the first reference distribution, the target number of cycles of the load spectrum of each different level is determined.

[0023] In an exemplary embodiment of the present disclosure, determining the original life distribution of the multi-level load spectrum model under the target level load spectrum includes:

[0024] Determining an original shape parameter of the Weibull distribution of fatigue damage of the multi-level load spectrum model based on the first reference distribution, and determining an original scale parameter of the Weibull distribution of fatigue damage of the multi-level load spectrum model;

[0025] According to the original shape parameters and the original scale parameters, the original Weibull life distribution of the multi-level load spectrum model under the target level load spectrum is determined.

[0026] In an exemplary embodiment of the present disclosure, the original life distribution is converted to obtain the target life distribution of the multi-level load spectrum model under the constant amplitude load spectrum, including:

[0027] Determining a predicted fatigue life of the multi-level load spectrum model under the multi-level load based on a probability statistics model corresponding to the multi-level load spectrum model, and determining a predicted fatigue life distribution of the multi-level load spectrum model according to the predicted fatigue life;

[0028] Based on the predicted fatigue life distribution and the original Weibull life distribution, a life consistency criterion is obtained, and based on the original Weibull life distribution, an optimal KS probability distribution criterion, an average consistency criterion, a variance consistency criterion, and a model consistency criterion are determined;

[0029] The original shape parameters are converted according to a life consistency criterion, an optimal KS probability distribution criterion, an average consistency criterion, a variance consistency criterion, and a model consistency criterion to obtain target shape parameters;

[0030] The original Weibull life distribution is adjusted based on the target shape parameter to obtain a target Weibull life distribution.

[0031] In an exemplary embodiment of the present disclosure, determining the average consistency criterion, the variance consistency criterion, and the model consistency criterion based on the original Weibull life distribution includes:

[0032] Calculating a first average value of the predicted fatigue life distribution and a second average value of the original Weibull life distribution, and determining an average consistency criterion according to a ratio of the first average value to the second average value;

[0033] Calculating a first variance of the predicted fatigue life distribution and a second variance of the original Weibull life distribution, and determining a variance consistency criterion according to a ratio of the first variance to the second variance;

[0034] A first model consistency ratio of the predicted fatigue life distribution and a second model consistency ratio of the original Weibull life distribution are calculated, and a model consistency criterion is determined according to the first model consistency ratio and the second model consistency ratio.

[0035] In an exemplary embodiment of the present disclosure, the equivalent simplified method of the aircraft load spectrum further includes:

[0036] Calculating a first stress amplitude of the constant amplitude spectrum of the original Weibull distribution and a second stress amplitude of the constant amplitude spectrum of the target Weibull distribution, and calculating a ratio of the first stress amplitude to the second stress amplitude;

[0037] The fatigue consistency of the multi-level load spectrum model is determined according to the ratio of the first stress amplitude to the second stress amplitude.

[0038] In an exemplary embodiment of the present disclosure, the equivalent simplified method of the aircraft load spectrum further includes:

[0039] The equal life curve of the multi-level load spectrum model is obtained, and the constant amplitude spectrum of the multi-level load spectrum model under any stress ratio is determined according to the equal life curve and the target Weibull distribution.

[0040] An equivalent simplification method for an aircraft load spectrum provided by an embodiment of the present disclosure, on the one hand, obtains an original multi-level load spectrum determined based on a multi-level load spectrum model corresponding to a full-size aircraft; then simplifies the original multi-level load spectrum based on an equivalent damage rule to obtain a target multi-level load spectrum; then determines the original life distribution of the multi-level load spectrum model under the target level load spectrum; finally, converts the original life distribution to obtain the target life distribution of the multi-level load spectrum model under the constant amplitude load spectrum; since the original multi-level load spectrum can be converted into the target multi-level load spectrum, then based on the target The life distribution of the multi-level load spectrum model under the constant amplitude load spectrum is obtained by using the target multi-level load spectrum, thereby realizing the equivalent simplification of the multi-level load spectrum. On the other hand, since the original life distribution of the multi-level load spectrum model under the target level load spectrum can be determined, and then the original life distribution is transformed to obtain the target life distribution of the multi-level load spectrum model under the constant amplitude load spectrum, the problem of low accuracy of the simplified load spectrum caused by the simplification method in the prior art being unable to ensure that the distribution of the number of blocks before and after the conversion is the same when the structure reaches fatigue failure can be avoided, thereby improving the accuracy of the target life distribution.

[0041] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0043] Figure 1 A flowchart schematically illustrates an equivalent simplified method for aircraft load spectrum according to an exemplary embodiment of the present disclosure.

[0044] Figure 2 An example diagram schematically illustrates a load time history experienced by a full-scale aircraft during a flight according to an example embodiment of the present disclosure.

[0045] Figure 3 An example diagram of a constant amplitude load spectrum according to an example embodiment of the present disclosure is schematically shown.

[0046] Figure 4 A flowchart of a method for simplifying an original multi-level load spectrum based on an equivalent damage rule to obtain a target multi-level load spectrum according to an exemplary embodiment of the present disclosure is schematically shown.

[0047] Figure 5 A flow chart schematically illustrates a method for converting the original life distribution to obtain a target life distribution of the multi-level load spectrum model under a constant amplitude load spectrum according to an exemplary embodiment of the present disclosure.

[0048] Figure 6 An example diagram of an iso-life curve according to an example embodiment of the present disclosure is schematically shown.

[0049] Figure 7 A block diagram schematically shows an equivalent simplified device of an aircraft load spectrum according to an exemplary embodiment of the present disclosure.

[0050] Figure 8 An electronic device for implementing an equivalent simplified method of aircraft load spectrum according to an exemplary embodiment of the present disclosure is schematically shown. DETAILED DESCRIPTION

[0051] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as being limited to the examples set forth herein; on the contrary, these embodiments are provided so that the present disclosure will be more comprehensive and complete, and the concepts of the example embodiments are fully conveyed to those skilled in the art. The described features, structures, or characteristics may be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced while omitting one or more of the specific details, or other methods, components, devices, steps, etc. may be adopted. In other cases, known technical solutions are not shown or described in detail to avoid obscuring various aspects of the present disclosure.

[0052] In addition, the accompanying drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and their repeated description will be omitted. Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0053] The loads that aircraft structures are subjected to during use include static loads, dynamic loads, fatigue loads, thermal loads, and many other different loads. Among them, fatigue loads have the following main characteristics: first, they are alternating loads; second, they act on the aircraft structure repeatedly. From this perspective, fatigue loads are also called repetitive loads, that is, fatigue loads are an alternating repetitive load, and the load spectrum is a description of this alternating repetitive load. Since the load spectrum is always generated when the aircraft is in use, the load spectrum can usually be called the service load spectrum.

[0054] The load spectrum used in aircraft design is the basis for structural strength calculation, damage tolerance and durability. The test verification of the fatigue life of full-scale aircraft structures can be carried out directly according to the standard load spectrum formed by the statistical specifications of the aircraft standard mission profile and the damage counting principle; however, even if the double life verification test is completed based on this method, the time and cost consumption are huge. Therefore, studying the simplified method of fatigue load spectrum has important engineering practical value for shortening the test cycle and improving technical and economic benefits.

[0055] In the process of practical application, the premise of fatigue load spectrum simplification technology is to determine the fatigue damage of the aircraft. Fatigue damage is a characteristic of the degradation of mechanical properties of aircraft components under various loads. For a long time in the past, fatigue damage theory has demonstrated many models; for example, the fatigue damage of the aircraft can be determined based on the early proposed method of equal damage conversion using linear cumulative damage theory (Miner rule); among them, in the process of equal damage conversion based on Miner rule, the engineering damage caused by each cyclic load can be quantitatively accumulated and calculated, which can be better applied to fatigue damage prediction under complex loads in engineering practice; however, this method is a linear and deterministic method, which does not consider the order effect of loads, so the accuracy of the fatigue damage obtained is low.

[0056] In order to solve the above problems, researchers have developed a series of damage determination models from the aspects of damage evolution curve, continuous damage mechanics, energy-based methods and crack extension concepts, and then determined the fatigue damage of the aircraft based on the damage determination model; however, the above-mentioned damage determination models did not consider the statistical characteristics of cumulative damage when determining fatigue load damage, which made the accuracy of the obtained fatigue load damage low. In order to solve this problem, the researchers used the reverse statistical inference method to fit the pSN curve of aircraft fatigue, thereby improving the prediction accuracy of small sample life data.

[0057] Furthermore, the fatigue load spectrum of general flight is a random sequence of random loads or simple multi-level load cycles, in which small stress load cycles account for a large proportion, and these loads cause relatively small damage to the structure compared with other load levels. In addition, the multi-level load spectrum has a great influence on the fatigue crack growth life of the full-aircraft acceleration test. Therefore, finding an effective method to simplify the multi-level load spectrum is an urgent problem that researchers need to solve. So far, the existing methods for simplifying the load spectrum include low-load interception, high-load acquisition, amplitude enhancement, severity spectrum, etc. In the process of load spectrum simplification, the interaction of loads and the influence of sequence effects are often considered. In response to the above simplification methods, researchers have proposed load spectrum simplification criteria, including finite objectives, damage consistency and damage equivalence criteria, among which the damage equivalence criteria are more commonly used in fatigue life estimation, fatigue load spectrum compilation and load spectrum simplification. The method of equivalent damage simplification is to simplify the original multi-level load spectrum into load blocks with fewer levels and convert them into equal-amplitude loads. The different understandings of the concepts of these two types of equivalent damage lead to different simplification effects.

[0058] The existing low-order load spectrum simplification method is: first, remove the load with low stress level; second, convert the damage caused by low load into the load with high stress level, so as to reduce the number of load cycles; however, this simplification method belongs to accelerated fatigue, and its difficulty lies in finding a definite method to make the statistical properties of the damage distribution caused by a loading block before and after simplification the same, that is, to ensure that the distribution of the number of blocks before and after conversion is the same when the structure reaches fatigue failure; and the fatigue life of the structure is the product of the number of loading blocks and the number of loading hours or the total number of cycles of a loading block. As the total number of cycles after simplification decreases, the corresponding life is shortened, so the accuracy of the simplified load spectrum is low.

[0059] Based on this, this example implementation first provides an equivalent simplified method for an aircraft load spectrum, which can be run on a terminal device, a server, a server cluster or a cloud server, etc. Of course, those skilled in the art can also run the method disclosed herein on other platforms as required, and this exemplary embodiment does not specifically limit this.

[0060] Specifically, refer to Figure 1 As shown, the equivalent simplified method of the aircraft load spectrum may include the following steps:

[0061] Step S110. Acquire an original multi-level load spectrum determined based on a multi-level load spectrum model corresponding to a full-scale aircraft;

[0062] Step S120. Simplify the original multi-level load spectrum based on the equivalent damage rule to obtain a target multi-level load spectrum; wherein the number of first stress levels of the original multi-level load spectrum is greater than the number of second stress levels of the target multi-level load spectrum;

[0063] Step S130. Determine the original life distribution of the multi-level load spectrum model under the target level load spectrum;

[0064] Step S140: converting the original life distribution to obtain a target life distribution of the multi-level load spectrum model under a constant amplitude load spectrum.

[0065] In the above-mentioned equivalent simplification method of the aircraft load spectrum, on the one hand, by obtaining the original multi-level load spectrum determined based on the multi-level load spectrum model corresponding to the full-size aircraft; then simplifying the original multi-level load spectrum based on the equivalent damage rule to obtain the target multi-level load spectrum; then determining the original life distribution of the multi-level load spectrum model under the target level load spectrum; finally, converting the original life distribution to obtain the target life distribution of the multi-level load spectrum model under the constant amplitude load spectrum; since the original multi-level load spectrum can be converted into the target multi-level load spectrum, and then the life distribution of the multi-level load spectrum model under the constant amplitude load spectrum is obtained based on the target multi-level load spectrum, the equivalent simplification of the multi-level load spectrum is achieved; on the other hand, since the original life distribution of the multi-level load spectrum model under the target level load spectrum can be determined; and then the original life distribution is converted to obtain the target life distribution of the multi-level load spectrum model under the constant amplitude load spectrum, the simplification method in the prior art can avoid the problem of low accuracy of the simplified load spectrum caused by the inability to ensure that the distribution of the number of blocks before and after the conversion is the same when the structure reaches fatigue failure, thereby improving the accuracy of the target life distribution.

[0066] Hereinafter, the equivalent simplified method of the aircraft load spectrum recorded in the exemplary embodiment of the present disclosure will be explained and illustrated in detail with reference to the accompanying drawings.

[0067] First, the purpose of the invention of the exemplary embodiment of the present disclosure is explained and illustrated. Specifically, the equivalent simplification method of the aircraft load spectrum recorded in the present disclosure can achieve the equivalent simplification of the aircraft load spectrum from two aspects: on the one hand: simplifying the original multi-level load spectrum into a load spectrum with fewer levels, and verifying it through the experimental data of the 5-level and 7-level load spectra; the equivalent damage here is not the equivalent fatigue life, but the equivalent number of spectrum blocks; on the other hand, according to a certain principle, the life distribution under the multi-level load spectrum is converted into the life distribution of the equal amplitude spectrum, that is, the equivalent damage is achieved through the equivalent fatigue life; at the same time, the simplification method proposed in the exemplary embodiment of the present disclosure is universal and is a predictive engineering method that does not rely on experimental data.

[0068] It should be noted that the purpose of the equivalent simplification method of the aircraft load spectrum recorded in the exemplary embodiment of the present disclosure is to simplify the original multi-level load spectrum into a smaller number of loads based on an equal number of loading blocks and an equal-amplitude spectrum taking into account equivalent fatigue life; in the process of actual application, firstly, a simplified method is proposed to reduce the lower stress level load of the descent section to the highest stress level under the low-high-low sequential planning; secondly, the feasibility of the method is verified by the experimental load spectrum, and it is proved that the low stress load of the ascending section cannot be converted into a high stress load through the equivalent damage law; in addition, the present disclosure also studies the simplification method of the multi-level load spectrum to the equal-amplitude spectrum, and compares the results of 5 conversion criteria.

[0069] The following will Figure 1 The equivalent simplified method of the aircraft load spectrum shown in is further explained and illustrated. Specifically:

[0070] In step S110 , an original multi-level load spectrum determined based on a multi-level load spectrum model corresponding to a full-scale aircraft is obtained.

[0071] Specifically, the load recorded here refers to the aircraft load; if classified according to the nature of the load, the aircraft load can be divided into static load, dynamic load, fatigue load and thermal load, etc.; among them, dynamic load can include vibration load, sound load and impact load, etc.; and from the perspective of mechanics, static load and dynamic load are mainly characterized by the rate of change of load, with the structural natural frequency as a reference, the load size, direction and point of action slowly changing over time is static load, and the load that changes rapidly is dynamic load; fatigue load is mainly characterized by the alternation and repeatability of load, no matter what load, as long as it acts on the aircraft structure repeatedly, it is fatigue load. Further, if classified according to the source of load, it can be divided into load caused by the external environment and load caused by the use of the structure; further, if classified according to the position and state of the aircraft, it can be divided into flight load and ground load, etc.; in the process of actual application, the corresponding category of load can be selected according to actual needs, and this example does not impose special restrictions on this.

[0072] Furthermore, the multiple levels recorded here refer to levels corresponding to different stress levels; for example, applying stresses of different magnitudes may correspond to loads of different levels; in actual application, the required load level may be determined according to actual needs, and this example does not impose any special restrictions on this.

[0073] Furthermore, the load spectrum recorded here can be understood as a graph formed by the change of load size over time, that is, the time history of load size; among them, the load time history experienced by a full-scale aircraft in one flight can be referred to Figure 2It should be noted that an alternating load in the load spectrum is a load cycle. The load size of a load cycle can usually be described by five parameters: maximum load, minimum load, load amplitude (or load range), load mean and load ratio. Figure 3 The constant amplitude stress spectrum shown is used to represent the load spectrum, where the load magnitude becomes the corresponding stress magnitude.

[0074] In step S120, the original multi-level load spectrum is simplified based on the equivalent damage rule to obtain a target multi-level load spectrum; wherein the number of first stress levels of the original multi-level load spectrum is greater than the number of second stress levels of the target multi-level load spectrum.

[0075] Specifically, refer to Figure 4 As shown, the original multi-level load spectrum is simplified based on the equivalent damage rule to obtain the target multi-level load spectrum, which can include the following steps:

[0076] Step S410, calculating the cycle life ratio of each load spectrum of different levels in the original multi-level load spectrum, and truncating the original multi-level load spectrum based on the cycle life ratio to obtain a truncated multi-level load spectrum.

[0077] Step S420, calculate the fatigue damage of each different level of load spectrum after truncation; wherein the multi-level load spectrum after truncation includes the first level load spectrum, the second level load spectrum, ..., the m+1th level load spectrum, ..., the 2m+1th level load spectrum; the fatigue damage includes the first level fatigue damage, the second level fatigue damage, ..., the m+1th level fatigue damage, ..., the 2m+1th level fatigue damage.

[0078] Specifically, the fatigue damage of each load spectrum at different levels after truncation can be calculated by the following formula (1):

[0079]

[0080] Among them, D i is the fatigue damage of the load spectrum at level i, N ij and N i is the random fatigue life, E i is the expected fatigue life, n i is the original number of cycles of the load spectrum of the i-th level, i is the load level of the stress of the i-th level; a i is a fixed exponent, f i is the hysteresis effect coefficient, S i is the stress amplitude of the stress at the i-th level; is the maximum value of the load level from level 1 to the stress of level i-1; v is the material constant.

[0081] Step S430, calculating a first reference distribution of each load spectrum at different levels according to the first average value and the first standard deviation of the fatigue damage, and determining a target number of cycles of each load spectrum at different levels based on the first reference distribution.

[0082] In this example embodiment, first, based on the first mean value and the first standard deviation of the fatigue damage, the first reference distribution of each different level of the load spectrum is calculated; specifically, it can be achieved in the following way: first, the m+1th level fatigue damage and the 2m+1th level fatigue damage are extracted from the fatigue damage, and the first mean value and the first standard deviation of the m+1th level fatigue damage and the 2m+1th level fatigue damage are calculated based on the maximum likelihood estimation method; secondly, based on the first mean value and the first standard deviation, the first reference distribution of the m+1th level load spectrum and the 2m+1th level load spectrum is determined.

[0083] Secondly, determining the target number of cycles for each different level of the load spectrum based on the first reference distribution can be achieved in the following way: taking the first reference distribution as a benchmark, and making the equivalent damage distribution corresponding to the target number of cycles infinitely close to the first reference distribution as a constraint condition, determining the target number of cycles for each different level of the load spectrum.

[0084] Step S440: replacing the original cycle number of the truncated multi-level load spectrum based on the target cycle number to obtain the target multi-level load spectrum.

[0085] The following will further explain and illustrate the specific process of determining the target multi-level load spectrum. Specifically, the specific process of determining the target multi-level load spectrum can be achieved by simplifying the multi-level load spectrum into a lower-level load spectrum by using the equivalent damage rule. In the actual application process, it can be achieved by the following methods:

[0086] First, the load level with too small fatigue damage is truncated, which generally corresponds to the first or last level of load; then the load level with lower stress is converted to the load level with the highest stress level. The specific steps of the simplified method are as follows:

[0087] Step 1: Cycle life ratio n for each load spectrum with different stress levels i / E i Sorting, assuming the maximum value is n (1) / E (1) , then judge whether the load level of the i-th stress level meets ni / E i <(n (1) / E (1) )·5%; if satisfied, truncate; if not, retain, and do not change the original order of the remaining load levels; where n i is the number of cycles under the i-th level stress level; E i is the fatigue life under the i-th stress level.

[0088] Step 2: Assume that the number of cycles for each level in the multi-level load spectrum is n 1 ,n 2 ,...,n m+1 ,...,n 2m+1 , the corresponding fatigue damage is D 1 ,D 2 ,…,D m+1 ,…,D 2m+1 For simplicity, the final load level (i.e., 2m+1) is converted to the maximum stress level (i.e., m+1) according to the equivalent damage, thus satisfying the equation And the number of cycles at the highest stress level is changed from n m+1 Increase to The specific solution process is as follows:

[0089] (1) A multi-level load spectrum fatigue damage probability calculation model is used, as shown in formula (1), to solve the damage caused by each level of load. This statistical model takes into account the load sequence effect of the multi-level load spectrum. In the fatigue load spectrum, when the difference between the high and low load levels is small, the hysteresis effect is small. On the contrary, the impact is greater. The load level in the descending section is affected by the load hysteresis effect of the highest stress level. It is precisely because of the existence of the hysteresis factor exp(-f) that the equivalent damage conversion in the probabilistic sense can be achieved.

[0090]

[0091] Among them, D i is the fatigue damage of the load spectrum at level i, N ij and N i is the random fatigue life, E i is the expected fatigue life, n i is the original number of cycles of the load spectrum of the i-th level, i is the load level of the stress of the i-th level; a i is a fixed exponent, f i is the hysteresis effect coefficient, S i is the stress amplitude of the stress at the i-th level; is the maximum value of the load level of stress from level 1 to level i-1; v is the material constant, and the specific value can be 2.

[0092] Furthermore, the load-related parameters of the two levels (2m+1 and m+1) are substituted into formula (1), 2000 groups are randomly selected, and then the damage of level 2 in each group is added together to obtain D under the maximum sample size. 2m+1 and D m+1 The damage data is estimated using the maximum likelihood method to obtain the mean E 0 and standard deviation The two damage distribution parameters of , the numerical sampling test takes the damage distribution as the reference distribution.

[0093] (2) Use binary search to find the appropriate number of cycles Make the damage distribution parameter caused by the m+1 level load of the cycle number approximately equal to the reference distribution parameter; specifically, first, assume that the cycle number The initial range is [a, b], where a is the original cycle number of the m+1 layer, that is, a = n m+1 ; Secondly, b is the equivalent damage criterion of Miner (Δn m+1 / S m+1 )=(n 2m+1 / S 2m+1 ) is determined; therefore b=n m+1 +Δn m+1 =n m+1 +(S m+1 / S 2m+1 )·n 2m+1 ;

[0094] For the convenience of representation, it is assumed that the damage parameters at the m+1 loading level under n cycles are E n and Obviously, the initial value satisfies E(a)<E 0 , E(b)>E 0 , i is the number of iterations; similarly, if the damage of the last two load levels (2m+1 and 2m) is converted to the maximum stress level (m+1), then And the number of cycles at the highest stress level is changed from n m+1 Increase to The specific solution steps are similar to the above. Simply add the three levels of damage in step 1 to get the D with the largest sample size. 2m+1 +D 2m +D m+1 The damage data is used as the reference distribution.

[0095] In step S130, the original life distribution of the multi-level load spectrum model under the target level load spectrum is determined.

[0096] Specifically, determining the original life distribution of the multi-level load spectrum model under the target level load spectrum can be achieved in the following way: first, determining the original shape parameters of the Weibull distribution of fatigue damage of the multi-level load spectrum model based on the first reference distribution, and determining the original scale parameters of the Weibull distribution of fatigue damage of the multi-level load spectrum model; secondly, determining the original Weibull life distribution of the multi-level load spectrum model under the target level load spectrum based on the original shape parameters and the original scale parameters. Specifically, in the actual application process, first, assume that the fatigue test data of the test structure under multi-level loads obeys the Weibull distribution with shape parameter X=4; then, use the Bayesian Jeffery method to estimate the original scale parameters and the double 95% life N 95 / 95 , and then substitute it into the pSN curve to obtain the first stress amplitude Sa of the constant amplitude spectrum corresponding to the multi-level load spectrum life distribution.

[0097] In step S140, the original life distribution is converted to obtain a target life distribution of the multi-level load spectrum model under a constant amplitude load spectrum.

[0098] Specifically, refer to Figure 5 As shown, converting the original life distribution to obtain the target life distribution of the multi-level load spectrum model under the constant amplitude load spectrum may include the following steps:

[0099] Step S510, determining a predicted fatigue life of the multi-level load spectrum model under the multi-level load based on a probability statistics model corresponding to the multi-level load spectrum model, and determining a predicted fatigue life distribution of the multi-level load spectrum model according to the predicted fatigue life;

[0100] Step S520, obtaining a life consistency criterion based on the predicted fatigue life distribution and the original Weibull life distribution, and determining an optimal KS probability distribution criterion, an average consistency criterion, a variance consistency criterion, and a model consistency criterion based on the original Weibull life distribution;

[0101] Step S530, converting the original shape parameters according to the life consistency criterion, the best KS probability distribution criterion, the average consistency criterion, the variance consistency criterion and the model consistency criterion to obtain the target shape parameters;

[0102] Step S540: adjusting the original Weibull life distribution based on the target shape parameter to obtain a target Weibull life distribution.

[0103] In an exemplary embodiment, determining the average consistency criterion, the variance consistency criterion, and the model consistency criterion based on the original Weibull life distribution can be achieved in the following manner: calculating the first average value of the predicted fatigue life distribution and the second average value of the original Weibull life distribution, and determining the average consistency criterion based on the ratio of the first average value to the second average value; calculating the first variance of the predicted fatigue life distribution and the second variance of the original Weibull life distribution, and determining the variance consistency criterion based on the ratio of the first variance to the second variance; calculating the first model consistency ratio of the predicted fatigue life distribution and the second model consistency ratio of the original Weibull life distribution, and determining the model consistency criterion based on the first model consistency ratio and the second model consistency ratio.

[0104] The specific determination process of the target life distribution will be further explained and illustrated below. Specifically, in the actual application process, the specific determination process of the target life distribution may include the following process:

[0105] Firstly, the fatigue test data of the test structure under multi-level loads are numerically simulated using the multi-level load spectrum probability statistical model to obtain the fatigue life of a large sample size; secondly, the life distribution of the model is estimated using the maximum likelihood method, and the shape parameter obtained is close to but not equal to 4; then, according to one of the five criteria described below, it is appropriately transformed into a life distribution with a shape parameter of 4, and the transformed distribution is used as the life distribution under a constant amplitude load. Finally, the transformed life parameter is substituted into the pSN curve to solve the stress amplitude of the constant amplitude spectrum. At the same time, the life distribution of the multi-level load spectrum model is approximately transformed into a Weibull distribution with a shape parameter of 4, that is, the life distribution on the pSN curve under a constant amplitude load is obtained, thereby obtaining the constant amplitude spectrum stress with the same effect. Since the shape parameter α in the two-parameter Weibull distribution has been determined, the result of the approximate transformation is only reflected in the change of the scale parameter β. Therefore, the following five approximate criteria are proposed to transform the life distribution of the model into a Weibull distribution with a shape parameter α of 4.

[0106] (1)N 95 / 95 Consistency Criteria

[0107] The double 95% life consistency criterion refers to the double 95% life N of the life distribution obtained by the probability statistics model and the Weibull distribution with a shape parameter of 4. 95 / 95 The fatigue life N with confidence level C and reliability R is C / R Defined as:

[0108]

[0109] in, is the estimate of the scale parameter, SC Is the confidence coefficient. For the Bayesian Jeffery method calculation:

[0110]

[0111] S R =(-lnR) -1 / α ; Formula (5)

[0112] in, is the percentile of the upper bound 1-C chi-square distribution with 2m degrees of freedom; S R is the reliability coefficient, S T It is the coefficient of the specimen, which reflects the difference between the specimen and the actual structure. In practical application, for small specimens, the coefficient of the specimen can be 1.3; for standard specimens, the coefficient of the specimen can be 1.

[0113] Fatigue life N 95 / 95 The conversion formula for consistency criterion calculation is as follows:

[0114]

[0115] Where m is the number of samples. In the model simulation of multi-level load spectrum test data, a total of 2000 groups of sampling tests were carried out, so m was set to 2000; where in formula (6), the subscript of the parameter corresponding to the predicted fatigue life distribution is 1, and the subscript of the parameter corresponding to the original Weibull life distribution is 2. Furthermore, given the constant parameter α 1 ,α 2 (α 2 =4), the fatigue life N can be obtained 95 / 95 The specific value of β 1 and β 2 ; Finally, β 2 Substituting into the S-β curve, the stress amplitude S corresponding to the constant amplitude spectrum can be calculated; at the same time, based on N 95 / 95 The consistency criterion shows that the N 95 / 95 Consistent with the multi-level load spectrum.

[0116] lgβ=B 1 lgS+A 1 ; Formula (7)

[0117] Among them, S, A 1 and B 1 is a constant parameter.

[0118] (2) Best Kolmogorov-Smirnov (KS) probability distribution approximation criterion

[0119] The approximate criterion is to find a scale parameter β in the Weibull distribution with a shape parameter of 4, so that the KS goodness-of-fit test statistic of the life distribution obtained by the probability statistical model is minimized. The KS statistic is expressed as:

[0120]

[0121] in, and is the exact error boundary between the empirical frequency and the theoretical distribution frequency. 2 Obtained by Matlab programming, it is substituted into the S-β curve shown in formula (7) to calculate the corresponding constant amplitude fatigue load.

[0122] (3) Average consistency criterion

[0123] The criterion is to make the mean of the life distribution obtained by the statistical model equal to the mean of the Weibull distribution with a shape parameter of 4. The mean is defined as (9):

[0124]

[0125] in, is the gamma function. Given α 1 , α 2 and β 1 , the scale parameter is calculated by formula (10):

[0126]

[0127] (4) Variance consistency criterion

[0128] The criterion is to make the variance of the life distribution obtained by the probability model equal to the variance of the Weibull distribution with a shape parameter of 4. The variance is defined as (11):

[0129]

[0130] Given α 1 , α 2 and β 1 , the scale parameter is calculated by formula (12):

[0131]

[0132] (5) Model consistency criteria

[0133] The criterion is to make the life distribution mode obtained by the statistical model equal to the Weibull distribution mode with a shape parameter of 4; the model consistency ratio M is obtained by formula (13).

[0134]

[0135] Given α 1 , α 2 and β 1 , the scale parameter is calculated by formula (14):

[0136]

[0137] So far, the specific calculation process of the life consistency criterion, the best KS probability distribution criterion, the average consistency criterion, the variance consistency criterion and the model consistency criterion has been completed. Under this premise, the original shape parameters can be converted based on the life consistency criterion, the best KS probability distribution criterion, the average consistency criterion, the variance consistency criterion and the model consistency criterion to obtain the target shape parameters; based on the target shape parameters, the original Weibull life distribution is adjusted to obtain the target Weibull life distribution.

[0138] Furthermore, the equivalent simplification method of the aircraft load spectrum may also include: calculating the first stress amplitude of the constant amplitude spectrum of the original Weibull distribution and the second stress amplitude of the constant amplitude spectrum of the target Weibull distribution, and calculating the ratio of the first stress amplitude and the second stress amplitude; judging the fatigue consistency of the multi-level load spectrum model according to the ratio of the first stress amplitude and the second stress amplitude. That is, in the process of actual application, the second stress amplitude of the constant amplitude spectrum obtained from the model life distribution can be compared with the first stress amplitude of the test data. Based on the statistical consistency fatigue damage model, the method of simplifying the multi-level load spectrum into a constant amplitude spectrum has a better prediction effect.

[0139] Furthermore, the equivalent simplified method of the aircraft load spectrum may also include: obtaining the iso-life curve of the multi-level load spectrum model, and determining the constant amplitude spectrum of the multi-level load spectrum model under any stress ratio according to the iso-life curve and the target Weibull distribution. Specifically, in the actual application process,

[0140] The simplified method proposed in this paper is only applicable under the same stress ratio and further simplifies the calculation. First, the life distribution of the multilayer load spectrum model is simplified to a constant amplitude spectrum under the same stress ratio using the method described above, and then it is converted to a constant amplitude spectrum under any stress ratio using the constant life diagram. The specific method is as follows:

[0141] The Goodman linear model is selected for the iso-life curve, and all intersect the horizontal axis at the same point R 0 , where R 0 is the ultimate strength of the structural material, such as Figure 6 Assume that the stress ratio R 0 The stress under m0 , S a0 ) is known, then the stress (Sm ,S a ). Here, the arbitrary stress ratio R is applicable to fatigue test, and the commonly used stress ratio is R = 0.06 or -1. According to the properties of similar triangles, we can get:

[0142]

[0143] Among them, S m is the mean stress, S a is the stress amplitude. S max is the maximum stress, S min is the minimum stress, σ 0 As a constant parameter, the fatigue stress ratio is defined as:

[0144]

[0145] therefore:

[0146]

[0147] In particular, when R 0 =1, that is, the given load is a symmetrical load. Simplify the above formula to (18). Therefore, given R0 and S a0 and R, we can get S a .

[0148]

[0149] So far, the equivalent simplified method of the aircraft load spectrum recorded in the exemplary embodiments of the present disclosure has been fully realized.

[0150] The following are embodiments of the device disclosed herein, which can be used to execute the method embodiments disclosed herein. For details not disclosed in the device embodiments disclosed herein, please refer to the method embodiments disclosed herein.

[0151] The exemplary embodiment of the present disclosure also provides an equivalent simplified device for aircraft load spectrum. Specifically, refer to Figure 7 As shown, the equivalent simplified device of the aircraft load spectrum may include a load spectrum acquisition module 710, a load spectrum simplification processing module 720, an original life distribution determination module 730 and a target life distribution module 740. Among them:

[0152] The load spectrum acquisition module 710 may be used to acquire an original multi-level load spectrum determined based on a multi-level load spectrum model corresponding to a full-scale aircraft;

[0153] The load spectrum simplification processing module 720 can be used to simplify the original multi-level load spectrum based on the equivalent damage rule to obtain a target multi-level load spectrum; wherein the number of first stress levels of the original multi-level load spectrum is greater than the number of second stress levels of the target level load spectrum;

[0154] The original life distribution determination module 730 may be used to determine the original life distribution of the multi-level load spectrum model under the target level load spectrum;

[0155] The target life distribution module 740 can be used to convert the original life distribution to obtain the target life distribution of the multi-level load spectrum model under the constant amplitude load spectrum.

[0156] In an exemplary embodiment of the present disclosure, the original multi-level load spectrum is simplified based on the equivalent damage rule to obtain a target multi-level load spectrum, including: calculating the cycle life ratio of the load spectrum of each different level in the original multi-level load spectrum, and truncating the original multi-level load spectrum based on the cycle life ratio to obtain the truncated multi-level load spectrum; calculating the fatigue damage of the load spectrum of each different level after the truncation; wherein the truncated multi-level load spectrum includes the first level load spectrum, the second level load spectrum, ..., the m+1th level load spectrum spectrum, …, 2m+1th level load spectrum; the fatigue damage includes the first level fatigue damage, the second level fatigue damage, …, the m+1th level fatigue damage, …, the 2m+1th level fatigue damage; according to the first mean value and the first standard deviation of the fatigue damage, the first reference distribution of the load spectrum of each different level is calculated, and based on the first reference distribution, the target number of cycles of the load spectrum of each different level is determined; based on the target number of cycles, the original number of cycles of the truncated multi-level load spectrum is replaced to obtain the target multi-level load spectrum.

[0157] In an exemplary embodiment of the present disclosure, calculating fatigue damage of each load spectrum at different levels after truncation includes:

[0158]

[0159] Among them, D i is the fatigue damage of the load spectrum at level i, N ij and N i is the random fatigue life, E i is the expected fatigue life, n i is the original number of cycles of the load spectrum of the i-th level, i is the load level of the stress of the i-th level; a i is a fixed exponent, f i is the hysteresis effect coefficient, S i is the stress amplitude of the stress at the i-th level; is the maximum value of the load level from level 1 to the stress of level i-1; v is the material constant.

[0160] In an exemplary embodiment of the present disclosure, a first reference distribution of each different level of load spectrum is calculated based on the first mean value and the first standard deviation of the fatigue damage, including: extracting the m+1th level fatigue damage and the 2m+1th level fatigue damage from the fatigue damage, and calculating the first mean value and the first standard deviation of the m+1th level fatigue damage and the 2m+1th level fatigue damage based on the maximum likelihood estimation method; determining the first reference distribution of the m+1th level load spectrum and the 2m+1th level load spectrum based on the first mean value and the first standard deviation.

[0161] In an exemplary embodiment of the present disclosure, a target number of cycles for each different level of the load spectrum is determined based on the first reference distribution, including: taking the first reference distribution as a benchmark, and determining the target number of cycles for each different level of the load spectrum with the constraint that the equivalent damage distribution corresponding to the target number of cycles is infinitely close to the first reference distribution.

[0162] In an exemplary embodiment of the present disclosure, the original life distribution of the multi-level load spectrum model under the target level load spectrum is determined, including: determining the original shape parameters of the Weibull distribution of fatigue damage of the multi-level load spectrum model based on a first reference distribution, and determining the original scale parameters of the Weibull distribution of fatigue damage of the multi-level load spectrum model; determining the original Weibull life distribution of the multi-level load spectrum model under the target level load spectrum based on the original shape parameters and the original scale parameters.

[0163] In an exemplary embodiment of the present disclosure, the original life distribution is converted to obtain the target life distribution of the multi-level load spectrum model under the constant amplitude load spectrum, including: based on the probability statistics model corresponding to the multi-level load spectrum model, determining the predicted fatigue life of the multi-level load spectrum model under the multi-level load, and determining the predicted fatigue life distribution of the multi-level load spectrum model according to the predicted fatigue life; based on the predicted fatigue life distribution and the original Weibull life distribution, obtaining a life consistency criterion, and based on the original Weibull life distribution, determining the best KS probability distribution criterion, average consistency criterion, variance consistency criterion and model consistency criterion; according to the life consistency criterion, the best KS probability distribution criterion, average consistency criterion, variance consistency criterion and model consistency criterion, converting the original shape parameters to obtain target shape parameters; adjusting the original Weibull life distribution based on the target shape parameters to obtain a target Weibull life distribution.

[0164] In an exemplary embodiment of the present disclosure, the average consistency criterion, the variance consistency criterion and the model consistency criterion are determined based on the original Weibull life distribution, including: calculating the first average value of the predicted fatigue life distribution and the second average value of the original Weibull life distribution, and determining the average consistency criterion according to the ratio of the first average value and the second average value; calculating the first variance of the predicted fatigue life distribution and the second variance of the original Weibull life distribution, and determining the variance consistency criterion according to the ratio of the first variance and the second variance; calculating the first model consistency ratio of the predicted fatigue life distribution and the second model consistency ratio of the original Weibull life distribution, and determining the model consistency criterion according to the first model consistency ratio and the second model consistency ratio.

[0165] In an exemplary embodiment of the present disclosure, the equivalent simplified device of the aircraft load spectrum further includes:

[0166] A stress amplitude calculation module, which can be used to calculate the first stress amplitude of the constant amplitude spectrum of the original Weibull distribution and the second stress amplitude of the constant amplitude spectrum of the target Weibull distribution, and calculate the ratio of the first stress amplitude to the second stress amplitude;

[0167] The fatigue consistency determination module can be used to determine the fatigue consistency of the multi-level load spectrum model according to the ratio of the first stress amplitude to the second stress amplitude.

[0168] In an exemplary embodiment of the present disclosure, the equivalent simplified device of the aircraft load spectrum further includes:

[0169] The horizontal amplitude spectrum determination module can be used to obtain the equal-life curve of the multi-level load spectrum model, and determine the constant amplitude spectrum of the multi-level load spectrum model under any stress ratio based on the equal-life curve and the target Weibull distribution.

[0170] The specific details of each module in the above-mentioned equivalent simplification device of the aircraft load spectrum have been described in detail in the corresponding equivalent simplification method of the aircraft load spectrum, so they will not be repeated here.

[0171] It should be noted that, although several modules or units of the device for action execution are mentioned in the above detailed description, this division is not mandatory. In fact, according to the embodiments of the present disclosure, the features and functions of two or more modules or units described above can be embodied in one module or unit. On the contrary, the features and functions of one module or unit described above can be further divided into multiple modules or units to be embodied.

[0172] In addition, although the steps of the method in the present disclosure are described in a specific order in the drawings, this does not require or imply that the steps must be performed in this specific order, or that all the steps shown must be performed to achieve the desired results. Additionally or alternatively, some steps may be omitted, multiple steps may be combined into one step, and / or one step may be decomposed into multiple steps, etc.

[0173] In an exemplary embodiment of the present disclosure, an electronic device capable of implementing the above method is also provided.

[0174] Those skilled in the art will appreciate that various aspects of the present disclosure may be implemented as systems, methods or program products. Therefore, various aspects of the present disclosure may be specifically implemented in the following forms, namely: complete hardware implementation, complete software implementation (including firmware, microcode, etc.), or a combination of hardware and software, which may be collectively referred to herein as "circuits", "modules" or "systems".

[0175] Refer to the following Figure 8 The electronic device 800 according to this embodiment of the present disclosure is described. Figure 8 The electronic device 800 shown is merely an example and should not bring any limitation to the functions and scope of use of the embodiments of the present disclosure.

[0176] like Figure 8 As shown, the electronic device 800 is in the form of a general computing device. The components of the electronic device 800 may include, but are not limited to: the at least one processing unit 810, the at least one storage unit 820, a bus 830 connecting different system components (including the storage unit 820 and the processing unit 810), and a display unit 840.

[0177] The storage unit stores program codes, which can be executed by the processing unit 810, so that the processing unit 810 performs the steps according to various exemplary embodiments of the present disclosure described in the above “Exemplary Method” section of this specification. For example, the processing unit 810 can perform the following steps: Figure 1 Step S110 shown in: obtaining an original multi-level load spectrum determined based on a multi-level load spectrum model corresponding to a full-scale aircraft; step S120: simplifying the original multi-level load spectrum based on the equivalent damage rule to obtain a target multi-level load spectrum; wherein the number of first stress levels of the original multi-level load spectrum is greater than the number of second stress levels of the target level load spectrum; step S130: determining the original life distribution of the multi-level load spectrum model under the target level load spectrum; step S140: converting the original life distribution to obtain the target life distribution of the multi-level load spectrum model under the constant amplitude load spectrum. .

[0178] The storage unit 820 may include a readable medium in the form of a volatile storage unit, such as a random access memory unit (RAM) 8201 and / or a cache memory unit 8202 , and may further include a read-only memory unit (ROM) 8203 .

[0179] The storage unit 820 may also include a program / utility 8204 having a set (at least one) of program modules 8205, such program modules 8205 including but not limited to: an operating system, one or more application programs, other program modules, and program data, each of which or some combination may include an implementation of a network environment.

[0180] Bus 830 may represent one or more of several types of bus structures, including a memory unit bus or memory unit controller, a peripheral bus, an accelerated graphics port, a processing unit, or a local bus using any of a variety of bus architectures.

[0181] The electronic device 800 may also communicate with one or more external devices 900 (e.g., keyboards, pointing devices, Bluetooth devices, etc.), may also communicate with one or more devices that enable a user to interact with the electronic device 800, and / or communicate with any device that enables the electronic device 800 to communicate with one or more other computing devices (e.g., routers, modems, etc.). Such communication may be performed via an input / output (I / O) interface 850. Furthermore, the electronic device 800 may also communicate with one or more networks (e.g., local area networks (LANs), wide area networks (WANs), and / or public networks, such as the Internet) via a network adapter 860. As shown, the network adapter 860 communicates with other modules of the electronic device 800 via a bus 830. It should be understood that, although not shown in the figure, other hardware and / or software modules may be used in conjunction with the electronic device 800, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage systems, etc.

[0182] Through the description of the above implementation, it is easy for those skilled in the art to understand that the example implementation described here can be implemented by software, or by software combined with necessary hardware. Therefore, the technical solution according to the implementation of the present disclosure can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, a USB flash drive, a mobile hard disk, etc.) or on a network, including several instructions to enable a computing device (which can be a personal computer, a server, a terminal device, or a network device, etc.) to execute the method according to the implementation of the present disclosure.

[0183] In an exemplary embodiment of the present disclosure, a computer-readable storage medium is also provided, on which a program product capable of implementing the above method of the present specification is stored. In some possible implementations, various aspects of the present disclosure may also be implemented in the form of a program product, which includes a program code, and when the program product is run on a terminal device, the program code is used to enable the terminal device to execute the steps according to various exemplary implementations of the present disclosure described in the above "Exemplary Method" section of the present specification.

[0184] According to the program product for implementing the above method in the embodiment of the present disclosure, it can adopt a portable compact disk read-only memory (CD-ROM) and include program code, and can be run on a terminal device, such as a personal computer. However, the program product of the present disclosure is not limited thereto. In this document, a readable storage medium can be any tangible medium containing or storing a program, which can be used by or in combination with an instruction execution system, an apparatus or a device.

[0185] The program product may use any combination of one or more readable media. The readable medium may be a readable signal medium or a readable storage medium. The readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or device, or any combination of the above. More specific examples (non-exhaustive list) of readable storage media include: an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0186] Computer readable signal media may include data signals propagated in baseband or as part of a carrier wave, in which readable program code is carried. Such propagated data signals may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. Readable signal media may also be any readable medium other than a readable storage medium, which may send, propagate, or transmit a program for use by or in conjunction with an instruction execution system, apparatus, or device.

[0187] The program code embodied on the readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wired, optical cable, RF, etc., or any suitable combination of the foregoing.

[0188] Program code for performing the operations of the present disclosure may be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java, C++, etc., and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user computing device, partially on the user device, as a separate software package, partially on the user computing device and partially on a remote computing device, or entirely on a remote computing device or server. In cases involving a remote computing device, the remote computing device may be connected to the user computing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computing device (e.g., through the Internet using an Internet service provider).

[0189] In addition, the above-mentioned figures are only schematic illustrations of the processes included in the method according to the exemplary embodiments of the present disclosure, and are not intended to be limiting. It is easy to understand that the processes shown in the above-mentioned figures do not indicate or limit the time sequence of these processes. In addition, it is also easy to understand that these processes can be performed synchronously or asynchronously, for example, in multiple modules.

[0190] Other embodiments of the present disclosure will be readily apparent to those skilled in the art after considering the specification and practicing the inventions invented herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art that are not invented by the present disclosure. The specification and examples are to be considered merely exemplary, and the true scope and spirit of the present disclosure are indicated by the claims.

Claims

1. An equivalent simplified method for aircraft load spectrum, characterized in that: include: Acquire an original multi-level load spectrum determined based on a multi-level load spectrum model corresponding to a full-scale aircraft; The original multi-level load spectrum is simplified based on the equivalent damage rule to obtain a target multi-level load spectrum; wherein the number of first stress levels of the original multi-level load spectrum is greater than the number of second stress levels of the target multi-level load spectrum; Determining the original life distribution of the multi-level load spectrum model under the target level load spectrum; The original life distribution is transformed to obtain a target life distribution of the multi-level load spectrum model under a constant amplitude load spectrum.

2. The equivalent simplified method of aircraft load spectrum according to claim 1, characterized in that: The original multi-level load spectrum is simplified based on the equivalent damage rule to obtain the target multi-level load spectrum, including: Calculating the cycle life ratio of each load spectrum of different levels in the original multi-level load spectrum, and truncating the original multi-level load spectrum based on the cycle life ratio to obtain a truncated multi-level load spectrum; Calculate the fatigue damage of each load spectrum at different levels after truncation; wherein the multi-level load spectrum after truncation includes a first-level load spectrum, a second-level load spectrum, ..., an m+1-th level load spectrum, ..., and a 2m+1-th level load spectrum; the fatigue damage includes a first-level fatigue damage, a second-level fatigue damage, ..., an m+1-th level fatigue damage, ..., and a 2m+1-th level fatigue damage; Calculating a first reference distribution of each load spectrum at different levels according to a first average value and a first standard deviation of the fatigue damage, and determining a target number of cycles of each load spectrum at different levels based on the first reference distribution; The original cycle number of the truncated multi-level load spectrum is replaced based on the target cycle number to obtain the target multi-level load spectrum.

3. The equivalent simplified method of aircraft load spectrum according to claim 2 is characterized in that: Calculate the fatigue damage of each load spectrum at different levels after truncation, including: Among them, D i is the fatigue damage of the load spectrum at level i, N ij and N i is the random fatigue life, E i is the expected fatigue life, n i is the original number of cycles of the load spectrum of the i-th level, i is the load level of the stress of the i-th level; a i is a fixed exponent, f i is the hysteresis effect coefficient, S i is the stress amplitude of the stress at the i-th level; is the maximum value of the load level from level 1 to the stress of level i-1; v is the material constant.

4. The equivalent simplified method of aircraft load spectrum according to claim 2, characterized in that: Calculating a first reference distribution of each load spectrum at different levels according to the first average value and the first standard deviation of the fatigue damage includes: Extracting the m+1th level fatigue damage and the 2m+1th level fatigue damage from the fatigue damage, and calculating a first average value and a first standard deviation of the m+1th level fatigue damage and the 2m+1th level fatigue damage based on a maximum likelihood estimation method; A first reference distribution of the (m+1)th level load spectrum and the (2m+1)th level load spectrum is determined based on the first average value and the first standard deviation.

5. The equivalent simplified method of aircraft load spectrum according to claim 4 is characterized in that: Determining a target number of cycles of each load spectrum at different levels based on the first reference distribution includes: Taking the first reference distribution as a benchmark and taking the equivalent damage distribution corresponding to the target number of cycles as a constraint condition that the equivalent damage distribution corresponding to the target number of cycles is infinitely close to the first reference distribution, the target number of cycles of the load spectrum of each different level is determined.

6. The equivalent simplified method of aircraft load spectrum according to claim 1, characterized in that: Determining the original life distribution of the multi-level load spectrum model under the target level load spectrum includes: Determining an original shape parameter of the Weibull distribution of fatigue damage of the multi-level load spectrum model based on the first reference distribution, and determining an original scale parameter of the Weibull distribution of fatigue damage of the multi-level load spectrum model; According to the original shape parameters and the original scale parameters, the original Weibull life distribution of the multi-level load spectrum model under the target level load spectrum is determined.

7. The equivalent simplified method of aircraft load spectrum according to claim 1, characterized in that: The original life distribution is converted to obtain the target life distribution of the multi-level load spectrum model under the constant amplitude load spectrum, including: Determining a predicted fatigue life of the multi-level load spectrum model under the multi-level load based on a probability statistics model corresponding to the multi-level load spectrum model, and determining a predicted fatigue life distribution of the multi-level load spectrum model according to the predicted fatigue life; Based on the predicted fatigue life distribution and the original Weibull life distribution, a life consistency criterion is obtained, and based on the original Weibull life distribution, an optimal KS probability distribution criterion, an average consistency criterion, a variance consistency criterion, and a model consistency criterion are determined; The original shape parameters are converted according to a life consistency criterion, an optimal KS probability distribution criterion, an average consistency criterion, a variance consistency criterion, and a model consistency criterion to obtain target shape parameters; The original Weibull life distribution is adjusted based on the target shape parameter to obtain a target Weibull life distribution.

8. The equivalent simplified method of aircraft load spectrum according to claim 7, characterized in that: Determining the average consistency criterion, the variance consistency criterion and the model consistency criterion based on the original Weibull life distribution includes: Calculating a first average value of the predicted fatigue life distribution and a second average value of the original Weibull life distribution, and determining an average consistency criterion according to a ratio of the first average value to the second average value; Calculating a first variance of the predicted fatigue life distribution and a second variance of the original Weibull life distribution, and determining a variance consistency criterion according to a ratio of the first variance to the second variance; A first model consistency ratio of the predicted fatigue life distribution and a second model consistency ratio of the original Weibull life distribution are calculated, and a model consistency criterion is determined according to the first model consistency ratio and the second model consistency ratio.

9. The equivalent simplified method of aircraft load spectrum according to claim 1, characterized in that: The equivalent simplified method of the aircraft load spectrum also includes: Calculating a first stress amplitude of the constant amplitude spectrum of the original Weibull distribution and a second stress amplitude of the constant amplitude spectrum of the target Weibull distribution, and calculating a ratio of the first stress amplitude to the second stress amplitude; The fatigue consistency of the multi-level load spectrum model is determined according to the ratio of the first stress amplitude to the second stress amplitude.

10. The equivalent simplified method of aircraft load spectrum according to claim 1, characterized in that: The equivalent simplified method of the aircraft load spectrum also includes: The equal life curve of the multi-level load spectrum model is obtained, and the constant amplitude spectrum of the multi-level load spectrum model under any stress ratio is determined according to the equal life curve and the target Weibull distribution.

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