Reliability numerical analysis method for strong coupling in temperature vibration environment

Abstract

The invention discloses a reliability numerical analysis method for strong coupling in a temperature vibration environment, and the method comprises the steps: carrying out the three-dimensional modeling of a to-be-analyzed product, dividing a built model into a plurality of grid units, and exporting the information of each grid unit; preprocessing a random vibration load to be added to obtain random vibration load excitation in a time domain; meanwhile, a temperature environment load to be added is preprocessed, and a temperature change function of physical parameters of a structural field under the temperature cycle condition in a time domain is obtained; based on the information of each grid unit, random vibration load excitation and a temperature change function of physical parameters of a structure field, through temperature-structure field coupling and vibration-structure field coupling, a matrix iterative calculation mode is utilized to analyze a temperature vibration strong coupling field, and a strain value and a stress value are obtained; the fatigue damage value and the service life of the product are calculated according to the strain value, and reliability numerical analysis in the temperature vibration coupling environment is achieved in combination with the stress value. The method has the advantages of high efficiency and high precision.

Description

Technical Field

[0001] The invention belongs to the technical field of reliability analysis, and in particular relates to a reliability numerical analysis method with strong coupling in a temperature-vibration environment. Background Art

[0002] Electronic component failure is a common fault phenomenon in electronic systems. It refers to the complete or partial loss of function, parameter drift, or intermittent occurrence of the above conditions during normal use of electronic components, which may cause the performance of the equipment or system to degrade or completely fail to work.

[0003] According to statistics, 55% of electronic component failures are caused by temperature changes, 20% by vibration and shock, 19% by moisture, and 6% by dust. It can be seen that under the action of operating stress or environmental stress, its failure must be caused by the corresponding mechanism, among which the influence of temperature and vibration is dominant, and when facing the loading conditions of simultaneous temperature and random vibration load, temperature and vibration load often have a certain coupling relationship, which makes the conventional reliability analysis method of electronic products have a large error compared with the actual situation.

[0004] At present, the commonly used analysis method for realizing the reliability of electronic products under temperature-vibration coupling conditions is mainly realized by finite element simulation technology. The main process is: first, the temperature cycle conditions and random vibration load conditions are applied through the finite element simulation software to obtain the stress-strain distribution cloud map, and then the fatigue life value of the product is obtained by calculation and prediction. Among them, the load is added by first performing a temperature cycle, and then the result of the temperature cycle is introduced as a prestress into the random vibration modal analysis in the frequency domain, and then a random vibration analysis is performed to obtain the stress and strain values, and the dangerous points with large stress values ​​are determined as dangerous parts, and then the Coffin-Manson formula is used to calculate the damage value Dt under the temperature cycle condition and the damage value Dv under the random vibration load, and then the total damage value under the temperature-vibration coupling condition is obtained by linear superposition of Miner's law, and the corresponding total fatigue life value can be obtained by taking the inverse of the total damage value.

[0005] However, the existing finite element simulation technology cannot well reflect the coupling mechanism between temperature and random vibration loads during coupling, and the temperature load under time domain conditions and the random vibration load under frequency domain cannot be applied simultaneously in a transient state, so it cannot match the environment under actual working conditions, further resulting in reduced accuracy. In addition, due to its complex and comprehensive calculation and processing system, the existing finite element simulation software has a slightly poor directionality in calculation, and often needs to process a lot of additional calculation workload, which takes a long time. Summary of the invention

[0006] In order to solve the above problems existing in the prior art, the present invention provides a reliability numerical analysis method with strong coupling under a temperature-vibration environment. The technical problem to be solved by the present invention is achieved by the following technical solutions:

[0007] In the first aspect, the present invention proposes a reliability numerical analysis method of strong coupling under a temperature-vibration environment, comprising:

[0008] Step 1: Perform 3D modeling on the product to be analyzed, divide the built model into several grid units, and export the information of each grid unit;

[0009] Step 2: Preprocess the random vibration load to be added to obtain the random vibration load excitation in the time domain; at the same time, preprocess the temperature environment load to be added to obtain the temperature variation function of the physical parameters of the structural field under the temperature cycle condition in the time domain;

[0010] Step 3: Based on the information of each grid unit, random vibration load excitation and temperature variation function of physical parameters of the structural field, through temperature-structure field coupling and vibration-structure field coupling, the temperature-vibration strong coupling field is analyzed by matrix iterative calculation to obtain the strain value and stress value of each grid unit;

[0011] Step 4: Calculate the fatigue damage value of the product based on the strain value of each grid unit, and calculate the product life based on the fatigue damage value, and combine the stress value to realize the numerical analysis of reliability under the temperature-vibration coupling environment.

[0012] Beneficial effects of the present invention:

[0013] The invention provides a reliability numerical analysis method of strong coupling under temperature-vibration environment. First, a three-dimensional model is made for the product to be analyzed, and it is divided into several grid units; then, the vibration and temperature cycle loads to be added are preprocessed to obtain the temperature variation function of the physical parameters of the random vibration load excitation and the structural field in the time domain; then, through the temperature-structure field coupling and the vibration-structure field coupling, the temperature-vibration strong coupling field is analyzed by matrix iterative calculation to obtain the strain value and stress value; finally, the fatigue damage value and life of the product are calculated according to the strain value, and the reliability numerical analysis under the temperature-vibration coupling environment is realized in combination with the stress value. Starting from the perspective of the coupling mechanism, the method converts the temperature cycle and the random vibration load into the excitation and temperature variation parameters in the time domain, and performs a more realistic transient analysis of the temperature cycle and the random vibration load in the time domain, and realizes the stress-strain numerical analysis of the temperature-vibration strong coupling field through matrix iterative calculation, thereby realizing the reliability analysis of electronic products under the temperature-vibration coupling condition. Compared with the existing finite element analysis method, it has the advantages of high efficiency and high precision.

[0014] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a flow chart of a reliability numerical analysis method of strong coupling under a temperature-vibration environment provided by an embodiment of the present invention;

[0016] Figure 2 It is a flow chart of another reliability numerical analysis method with strong coupling in a temperature-vibration environment provided by an embodiment of the present invention;

[0017] Figure 3 It is a schematic diagram of tetrahedral grid unit division using a through silicon via structure as an example provided by an embodiment of the present invention;

[0018] Figure 4 is a schematic diagram of a random vibration load signal in the time domain obtained by inverse Fourier transform according to an embodiment of the present invention;

[0019] Figure 5 is a schematic diagram of the change of the thermal expansion coefficient over time provided by an embodiment of the present invention;

[0020] Figure 6 is a schematic diagram of the change of thermal conductivity over time provided by an embodiment of the present invention;

[0021] Figure 7 is a schematic diagram of the change of Young's modulus over time provided by an embodiment of the present invention;

[0022] Figure 8 It is a schematic diagram of a process for solving stress and strain using a numerical analysis method provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Please see the joint Figure 1 and Figure 2 , Figure 1 is a flow chart of a reliability numerical analysis method of strong coupling under a temperature-vibration environment provided by an embodiment of the present invention, Figure 2 1 is a flow chart of another method for numerical analysis of reliability of strong coupling under temperature-vibration environment provided by an embodiment of the present invention. The method for numerical analysis of reliability of strong coupling under temperature-vibration environment provided by the present invention mainly comprises the following steps:

[0025] Step 1: Perform 3D modeling on the product to be analyzed, divide the built model into several grid units, and export the information of each grid unit.

[0026] First, obtain the structural parameters of the product to be analyzed, and perform three-dimensional modeling in the modeling software based on the structural parameters;

[0027] Specifically, taking the Through Silicon Via (TSV) structure as an example, we can obtain parameters such as the thickness and radius of the upper and lower RDL layers, the diameter and height of the copper pillar, the thickness and height of the silicon dioxide buffer layer and the silicon substrate layer, and use 3D modeling software to establish a 3D model of the TSV.

[0028] Then, the constructed model is divided into tetrahedral grid units to obtain several grid units, such as Figure 3 shown.

[0029] Finally, the information of each divided grid unit is derived, wherein the information of each grid unit includes the material of the grid unit, the coordinates of the four points constituting the grid unit, and the number of the grid unit.

[0030] It can be understood that each grid unit has a unique material and thus also has parameters such as Poisson's ratio corresponding to the material. Based on the shape of the grid unit division, for example, the present embodiment is a tetrahedral grid unit, each grid unit also has a specific shape function.

[0031] Step 2: Preprocess the random vibration load to be added to obtain the random vibration load excitation in the time domain; at the same time, preprocess the temperature environment load to be added to obtain the temperature variation function of the physical parameters of the structural field under the temperature cycle conditions in the time domain.

[0032] Specifically, the random vibration load to be added is preprocessed to obtain the random vibration load excitation in the time domain; including:

[0033] 21) Determine the power spectrum density diagram of random vibration based on the material of the product to be analyzed, and obtain the random vibration power spectrum signal to be added.

[0034] Generally speaking, if there are no special requirements, the power spectrum density diagram of random vibration can be directly selected from the national military standard, and the random vibration power spectrum signal to be added can be selected accordingly.

[0035] 22) Use inverse Fourier transform to convert the random vibration power spectrum signal from the frequency domain to the time domain to obtain the time domain random load signal.

[0036] Since structures such as TSV cannot generate vibrations out of thin air in actual situations, the model vibration action form adopted by the present invention is to convert the vibration action of the bottom of the fixed model into a form of force acting on various parts of the structure, which is more in line with actual conditions.

[0037] The random vibration load is preprocessed, and the random vibration power spectrum signal in the frequency domain is converted to the time domain using the inverse Fourier transform. The formula of the inverse Fourier transform is as follows:

[0038]

[0039] Where f(t) is the time domain signal, F(jω) is the frequency domain signal, ω is the angular frequency, and e jωt is a complex exponential function, is the scale factor.

[0040] 23) The random vibration load signal in the time domain is multiplied by the model mass to obtain the load excitation of the force, which is used as the random vibration load excitation in the time domain.

[0041] After inverse Fourier transform processing, the time domain random vibration load signal is obtained as follows: Figure 4 As shown, its ordinate is acceleration g. In order to better meet the application analysis of the force field, the data of the random vibration load signal in the time domain is multiplied by the model mass to obtain the form of force load excitation. The conversion of random vibration load in the frequency domain into force load excitation in the time domain is realized.

[0042] Furthermore, the temperature environment load to be added is preprocessed to obtain the temperature variation function of the material parameters under the temperature cycle condition in the time domain, including:

[0043] 2a) Determine the temperature cycling conditions.

[0044] Generally speaking, if there are no special requirements, the temperature variation range, that is, the temperature cycle conditions, is selected from the national military standard.

[0045] 2b) Under temperature cycle conditions, the interpolation method is used to express the physical parameters of the structural field as a function form related to temperature, thereby obtaining the temperature-dependent function of the physical parameters of the structural field under temperature cycle conditions in the time domain.

[0046] Generally speaking, the physical parameters of the structural field are sensitive to temperature T. These physical parameters include the thermal expansion coefficient α, Young's modulus E, thermal conductivity k, etc., that is, these physical parameters can be expressed as functions of temperature T, namely α(T), E(T) and k(T), etc.

[0047] Based on this, this embodiment uses the interpolation method to express the temperature variation functions of the physical parameters of the structural field as shown in the following formula:

[0048]

[0049] In the formula, A n is the interpolation coefficient, [T0,T1] is the interpolation interval.

[0050] Based on the obtained temperature variation function, the thermal expansion coefficient, thermal conductivity and Young's modulus can be obtained as follows: Figure 5 , 6 , as shown in 7.

[0051] At this point, the temperature variation characteristics of the material corresponding to each grid unit can be obtained.

[0052] Step 3: Based on the information of each grid unit, random vibration load excitation and temperature variation function of the physical parameters of the structural field, through temperature-structure field coupling and vibration-structure field coupling, the temperature-vibration strong coupling field is analyzed by matrix iterative calculation to obtain the strain value and stress value of each grid unit.

[0053] Optionally, as an implementation method, the present embodiment may input relevant data into a matlab platform for relevant calculation and analysis.

[0054] In this embodiment, after obtaining the temperature-dependent characteristics of the material, the temperature-dependent iteration method is used to solve each time step of the field equation in consideration of its nonlinear influence on the equations. The temperature field calculation at the current time step is performed in units of time t, and at the same time, the stiffness matrix and other information of each mesh unit also satisfies the time step, and the stress and strain calculation of each mesh unit is realized through iterative solution.

[0055] Specifically, this embodiment calculates stress and strain by building a matrix in the coupling field. First, the temperature distribution, time step, unit number, stress value and strain value of each unit are initialized to ensure that the temperature value, stress and strain value of each grid unit starting from number 1 at the first second, i.e. t=1s, are solved. After the temperature field distribution, stress and strain values ​​of all units in a time step are solved, the various solutions in the next time step are entered. Since the temperature value of the current moment and the current unit is used when solving the stress and strain values ​​of each unit, this solution process belongs to the temperature change iterative calculation under the time unit. Finally, the stress and strain values ​​under the required temperature cycle conditions are calculated through matrix iteration, and the whole process of solving stress and strain using numerical analysis is completed.

[0056] See also Figure 8 , Figure 8 is a flow chart of solving stress and strain using numerical analysis method provided by an embodiment of the present invention, then step 3 can be specifically implemented according to the following sub-steps 31)-35):

[0057] 31) Initialize the time step and the temperature field distribution, equivalent stress value and equivalent strain value of each grid cell.

[0058] 32) Within the current time step, calculate the temperature increment under the adjacent time step and update the temperature field distribution of each grid cell.

[0059] In this embodiment, the temperature field distribution T(x, y, z, t) can be obtained by the heat conduction equation, which describes the change of the temperature of different grid units over time. The heat conduction equation is shown as follows:

[0060]

[0061] Where ρ represents the material density (unit: kg / m 3 ), c represents specific heat (unit: J / (kg·K)), T represents temperature (unit: K), represents the partial derivative of temperature T with respect to time, k represents thermal conductivity (W / (m·K)), Q is the internal heat source (W / m 3 ).

[0062] Through the above formula, the temperature distribution data of each grid unit in the current time step can be obtained.

[0063] 33) According to the temperature field distribution of each grid unit and the temperature variation function of the physical parameters of the structural field, the physical parameter value of the structural field of each grid unit is obtained; and the material stiffness matrix is ​​calculated.

[0064] Specifically, according to the temperature distribution data of each grid unit, combined with the temperature variation function in step 2b), the corresponding parameter values ​​including thermal expansion coefficient, thermal conductivity and Young's modulus can be obtained.

[0065] At the same time, the material stiffness matrix can also be calculated based on the calculated parameter values. The calculation formula is:

[0066]

[0067] Where D represents the material stiffness matrix, E represents Young's modulus, and ν represents Poisson's ratio.

[0068] It is understandable that after determining the relevant parameter values ​​of each grid unit, the corresponding mass matrix M, damping matrix C, and derivative matrix B of the shape function for describing the relationship between strain and unit displacement can be obtained according to the shape function of each grid unit.

[0069] Furthermore, the stiffness matrix D of each grid element can be obtained k , the calculation formula is as follows:

[0070] Dk =∫ V B T DBdv;

[0071] Where V represents the volume of the grid unit, and B represents the derivative matrix of the shape function of the grid unit.

[0072] 34) Based on the physical parameter values ​​of the structural field and the material stiffness matrix, the stress and strain calculations are performed on each grid unit under the temperature field. At the same time, combined with the random vibration load excitation, the stress and strain calculations are performed on each grid unit under the vibration field, and the corresponding strain values ​​and stress values ​​of each grid unit under the temperature field and the vibration field are obtained.

[0073] Specifically, the stress and strain calculations under the temperature field are performed for each grid unit, including:

[0074] 34a) Based on the thermal expansion coefficient in the physical parameter value of the structural field, the thermal strain value under the temperature field is calculated using the thermal strain equation. The calculation formula is as follows:

[0075] ε1=α(T-T0)I;

[0076] In the formula, ε1 represents the thermal strain value under the temperature field, α represents the thermal expansion coefficient, T represents the current temperature, T0 represents the reference temperature, and I represents the unit matrix;

[0077] 34b) Calculate the corresponding thermal stress value according to the thermal strain value under the temperature field, and the calculation formula is:

[0078] σ1=D·ε1;

[0079] Where σ1 represents the thermal stress value under temperature field.

[0080] It can be understood that the thermal strain value and thermal stress value calculated by steps 34a) and 34b) are the strain value and stress value under the temperature field; wherein the strain value includes the normal strain value and the shear strain value.

[0081] Furthermore, in this embodiment, the stress and strain calculation under the vibration field is performed on each grid unit, specifically including:

[0082] 34A) Based on the random vibration load excitation, the displacement vector is calculated using the dynamic equations to obtain the displacement matrix.

[0083] Specifically, the dynamics equations describe the motion of a system under the action of external forces and are usually expressed as:

[0084]

[0085] Where M represents the mass matrix determined by the shape function, represents the acceleration vector, C represents the damping matrix determined by the shape function, represents the velocity vector, u(t) represents the displacement vector, F(t) represents the random vibration load excitation, and D k represents the stiffness matrix of each mesh unit, and u(t) represents the displacement vector, that is, the displacement matrix to be solved. Once the mesh unit is determined, M and C are also determined.

[0086] By solving the above formula, we can obtain the displacement vector u(t), and then the displacement matrix U.

[0087] 34B) The strain value under the vibration field is calculated according to the displacement matrix, and the calculation formula is:

[0088] ε2=B*U;

[0089] Wherein, ε2 represents the strain value under the vibration field, B represents the derivative matrix of the shape function of the grid unit, which is the matrix obtained by differentiating the shape function with respect to the spatial coordinates. The shape function is determined by the shape of the grid unit, and U represents the displacement matrix obtained in step 34A).

[0090] 34C) Calculate the corresponding stress value according to the strain value under the vibration field, and the calculation formula is:

[0091] σ2=D·ε2;

[0092] In the formula, σ2 represents the stress value under the vibration field; D represents the stiffness matrix;

[0093] 35) Based on the strain value and stress value of each mesh unit under the temperature field and the vibration field, the equivalent stress value and the equivalent strain value of the corresponding mesh unit are updated.

[0094] Specifically, for the thermal strain values ​​under the temperature field obtained in step 34a), including normal strain values ​​and shear strain values, the corresponding equivalent stress values ​​and equivalent strain values ​​can be calculated using the Von Mises criterion.

[0095] Correspondingly, the strain value under the vibration field calculated in step 34B) also includes a normal strain value and a shear strain value, and the corresponding equivalent stress value and equivalent strain value can also be calculated based on the Von Mises criterion.

[0096] For the specific implementation scheme of calculating equivalent stress and equivalent strain by using the Von Mises criterion, reference may be made to the existing related technologies, which will not be described in detail in this embodiment.

[0097] According to the calculated results, the equivalent stress value and equivalent strain value of each grid unit under the temperature field and vibration field are updated.

[0098] 36) Increase the time step by one and repeat steps 32)-35) to implement the iterative calculation of temperature change under the time unit to obtain the final strain value and stress value, as well as the equivalent stress value and equivalent strain value of each grid unit.

[0099] Step 4: Calculate the fatigue damage value of the product based on the strain value of each grid unit, and calculate the product life based on the fatigue damage value, and combine the stress value to realize the numerical analysis of reliability under the temperature-vibration coupling environment.

[0100] 41) Based on the strain value under the temperature field, the Engelmaier-modified Coffin-Manson model is used to calculate the fatigue damage value of each grid element under the temperature field.

[0101] Specifically, this embodiment uses the Engelmaier modified Coffin-Manson model to calculate the fatigue damage value under the temperature field. The model incorporates parameters such as cycle frequency, material and temperature into the equation, which is called the Engelmaier model, as shown in the following formula:

[0102]

[0103] Where N f represents the average fatigue cycle, Δγ is the cyclic shear strain value, which can be used to calculate the shear strain value in the strain value under the temperature field obtained in step 34a), ε' f is the fatigue ductility coefficient, which can be taken as 0.325 according to the material experience. c is the fatigue ductility index, and its expression is:

[0104] c=-0.442-6×10 -4 T avg +1.74×10 -2 ×ln(1+f);

[0105] Among them, T avg is the average temperature of the cyclic load in °C, and f is the cycle frequency in cycles per day.

[0106] The average fatigue cycle N is calculated by the above formula f Then multiply it by the time of temperature cycle condition, that is, N f ×t 温度循环条件的时间 , the life span under the temperature field can be obtained.

[0107] It should be noted that since the life value under temperature cycling cannot be directly linearly superimposed with the life value under random vibration conditions obtained later, and according to the Palmgren-Miner law, the damage values ​​can be linearly superimposed, the life value obtained in this embodiment is first converted into a damage value so as to be linearly superimposed with the fatigue damage value under the vibration field later.

[0108] According to the definition of cyclic damage, the fatigue damage value D under temperature field t is the inverse of life span, that is:

[0109]

[0110] 42) Based on the equivalent strain value under the vibration field, the Coffin-Manson model is used to calculate the fatigue damage value of each grid unit under the vibration field.

[0111] Specifically, according to relevant research, the elastic slope and plastic slope are -0.12 and -0.6 respectively, which are called universal slopes. Substituting the universal slope into the total strain amplitude and life relationship, the expression is as follows:

[0112]

[0113] In the formula, Δε t is the total strain amplitude, which can be substituted into the equivalent strain value under the vibration field obtained in step 35), σ u is the ultimate tensile strength of the material, E represents Young's modulus, N v Represents the lifespan in the time domain under a vibration field.

[0114] Through the above formula, we can solve the life span N in the time domain. v , take the inverse to get the fatigue damage value D under the vibration field v ,Right now:

[0115]

[0116] 43) Palmgren-Miner law is used to add the fatigue damage value of each grid unit under the temperature field and the fatigue damage value under the vibration field, and take the inverse to obtain the life of each grid unit under the temperature-vibration coupling environment.

[0117] Specifically, in this embodiment, the fatigue damage value D of each grid unit under random vibration load is calculated. v And the fatigue damage value D under temperature cycle load t Perform linear superposition to obtain the total damage D total , take D total The reciprocal of can be used to obtain the life value of the product under temperature-vibration coupling conditions.

[0118] 44) According to the life of each grid unit in the temperature-vibration coupling environment, combined with the equivalent stress value of each grid unit in the temperature field and the equivalent stress value in the vibration field, the reliability analysis of the product can be carried out.

[0119] Specifically, the life of each grid unit in a temperature-vibration coupling environment can directly reflect the reliability of that location. In addition, the total equivalent stress value of each grid unit in a temperature-vibration coupling environment can be obtained based on the equivalent stress value of each grid unit in a temperature field and the equivalent stress value in a vibration field, so as to determine the dangerous parts according to the points with larger total stress values, and further realize reliability analysis.

[0120] The present invention provides a reliability numerical analysis method with strong coupling under temperature-vibration environment. The method starts from the perspective of coupling mechanism, converts temperature cycles and random vibration loads into excitation and temperature variation parameters in the time domain, performs a more realistic transient analysis of temperature cycles and random vibration loads in the time domain, and realizes the stress-strain numerical analysis of the temperature-vibration strong coupling field through matrix iterative calculation, thereby realizing the reliability analysis of electronic products under temperature-vibration coupling conditions. Compared with the existing finite element analysis method, the method has the advantages of high efficiency and high precision.

[0121] The method can firstly perform reliability analysis on electronic products under temperature-vibration coupling environment under highly unified time domain conditions, without setting prestress and solving the problem that the vibration load under frequency domain cannot be transiently analyzed under time domain in simulation software. And under unified time domain, because temperature change will cause the Young's modulus, thermal conductivity, thermal expansion coefficient and other parameters of the material to change and thus affect the rigidity of the structure, so that the natural frequency of the structure changes, then at this time, random vibration load is applied to the structure, and the effect of the random vibration load will also change due to the change of the natural frequency. And the above-mentioned temperature-variable parameter changes are also analyzed in the time domain, so the reliability analysis closer to the actual application environment is realized through the influence relationship between temperature-structure-vibration field. And the numerical analysis calculation of the matrix iteration operation of temperature-vibration directly performed by the matlab platform has stronger directionality, so it is more efficient and accurate than the analysis directly performed in the finite element simulation software. According to the example verification, the strong coupling numerical analysis method of the present invention is 19% more accurate than the traditional finite element analysis method, and the time is shortened by 13%.

[0122] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A numerical analysis method for reliability of strong coupling under temperature and vibration environment, characterized in that: include: Step 1: Perform 3D modeling on the product to be analyzed, divide the built model into several grid units, and export the information of each grid unit; Step 2: Preprocess the random vibration load to be added to obtain the random vibration load excitation in the time domain; at the same time, preprocess the temperature environment load to be added to obtain the temperature variation function of the physical parameters of the structural field under the temperature cycle condition in the time domain; Step 3: Based on the information of each grid unit, the random vibration load excitation and the temperature variation function of the physical parameters of the structural field, through temperature-structure field coupling and vibration-structure field coupling, the temperature-vibration strong coupling field is analyzed by matrix iterative calculation to obtain the strain value and stress value of each grid unit; Step 4: Calculate the fatigue damage value of the product according to the strain value of each grid unit, calculate the product life according to the fatigue damage value, and realize the numerical analysis of reliability in the temperature-vibration coupling environment in combination with the stress value.

2. According to claim 1, a reliability numerical analysis method of strong coupling under temperature and vibration environment is characterized in that: Step 1 specifically includes: Obtain various structural parameters of the product to be analyzed, and perform three-dimensional modeling in a modeling software based on the structural parameters; Divide the constructed model into tetrahedral mesh units and export the information of each mesh unit after division.

3. According to claim 1, a reliability numerical analysis method of strong coupling under temperature and vibration environment is characterized in that: In step 2, the random vibration load to be added is preprocessed to obtain the random vibration load excitation in the time domain; including: 21) Determine the power spectrum density diagram of random vibration based on the material of the product to be analyzed, and obtain the random vibration power spectrum signal to be added; 22) converting the random vibration power spectrum signal from the frequency domain to the time domain by inverse Fourier transform to obtain a time domain random vibration load signal; 23) Multiplying the time domain random vibration load signal by the model mass to obtain a force load excitation as the random vibration load excitation in the time domain.

4. According to claim 1, a reliability numerical analysis method of strong coupling under temperature and vibration environment is characterized in that: In step 2, the temperature environment load to be added is preprocessed to obtain the temperature variation function of the material parameters under the temperature cycle condition in the time domain, including: 2a) Determine the temperature cycle conditions; 2b) Under the temperature cycle condition, the physical parameters of the structural field are expressed as a function form related to temperature by using an interpolation method, thereby obtaining a temperature-dependent function of the physical parameters of the structural field under the temperature cycle condition in the time domain; The physical parameters of the structural field include thermal expansion coefficient, thermal conductivity, and Young's modulus.

5. The reliability numerical analysis method of strong coupling under temperature-vibration environment according to claim 4 is characterized in that: Step 3 specifically includes: 31) Initialize the time step and the temperature field distribution, equivalent stress value and equivalent strain value of each grid unit; 32) In the current time step, calculate the temperature increment in the adjacent time step and update the temperature field distribution of each grid cell; 33) according to the temperature field distribution of each grid unit and the temperature variation function of the physical parameters of the structural field, the physical parameter value of the structural field of each grid unit is obtained; and the material stiffness matrix is ​​calculated; 34) Based on the physical parameter values ​​of the structural field and the material stiffness matrix, the stress and strain of each grid unit under the temperature field are calculated. At the same time, combined with the random vibration load excitation, the stress and strain of each grid unit under the vibration field are calculated, and the strain value and stress value of each grid unit under the temperature field and the vibration field are obtained accordingly; 35) updating the equivalent stress value and the equivalent strain value of the corresponding grid unit based on the strain value and the stress value of each grid unit under the temperature field and the vibration field; 36) Increase the time step by one and repeat steps 32)-35) to implement the iterative calculation of temperature change under the time unit to obtain the final strain value and stress value, as well as the equivalent stress value and equivalent strain value of each grid unit.

6. The reliability numerical analysis method of strong coupling under temperature and vibration environment according to claim 5 is characterized in that: In step 32), the temperature field distribution of each grid unit is calculated using the heat conduction equation; wherein the heat conduction equation is expressed as: In the formula, ρ represents the material density, c represents the specific heat capacity, represents the partial derivative of temperature T with respect to time, represents the temperature increment in adjacent time steps, k represents the thermal conductivity, and Q represents the heat source inside the grid unit.

7. The reliability numerical analysis method of strong coupling under temperature-vibration environment according to claim 5 is characterized in that: In step 33), the calculation formula of the material stiffness matrix is: Where D represents the material stiffness matrix, E represents Young's modulus, and ν represents Poisson's ratio.

8. The reliability numerical analysis method of strong coupling under temperature-vibration environment according to claim 7 is characterized in that: In step 34), the stress and strain calculation under the temperature field is performed for each grid unit, specifically including: Based on the thermal expansion coefficient in the physical parameter value of the structural field, the thermal strain value under the temperature field is calculated using the thermal strain equation. The calculation formula is as follows: ε1=α(T-T0)I; In the formula, ε1 represents the thermal strain value under the temperature field, α represents the thermal expansion coefficient, T represents the current temperature, T0 represents the reference temperature, and I represents the unit matrix; The corresponding thermal stress value is calculated according to the thermal strain value under the temperature field and the material stiffness matrix, and the calculation formula is: σ1=D·ε1; Where σ1 represents the thermal stress value under the temperature field, and D represents the material stiffness matrix.

9. The method for numerical analysis of strong coupling reliability under temperature-vibration environment according to claim 7, characterized in that: In step 34), the stress and strain calculation under the vibration field is performed on each grid unit, specifically including: According to the random vibration load excitation, the displacement vector is calculated using the dynamic equation group to obtain the displacement matrix; wherein the dynamic equation group is expressed as: Where M represents the mass matrix determined by the shape function, represents the acceleration vector, C represents the damping matrix determined by the shape function, represents the velocity vector, u(t) represents the displacement vector, F(t) represents the random vibration load excitation, and D k Represents the stiffness matrix of each grid unit, which is calculated from the material stiffness matrix and the calculation formula is: D k =∫ V B T DBdv; In the formula, V represents the volume of the grid unit, and B represents the derivative matrix of the shape function of the grid unit; The strain value under the vibration field is calculated according to the displacement matrix, and the calculation formula is: ε2=B*U In the formula, ε2 represents the strain value under the vibration field, and U represents the displacement matrix; The corresponding stress value is calculated according to the strain value under the vibration field, and the calculation formula is: σ2=D·ε2; Where σ2 represents the stress value under the vibration field, and D represents the material stiffness matrix.

10. A reliability numerical analysis method for strong coupling under temperature-vibration environment according to claim 9, characterized in that: Step 4 specifically includes: Based on the strain value under the temperature field, the Engelmaier modified Coffin-Manson model is used to calculate the fatigue damage value of each grid element under the temperature field; Based on the equivalent strain value under the vibration field, the Coffin-Manson model is used to calculate the fatigue damage value of each grid element under the vibration field; Palmgren-Miner law is used to add the fatigue damage value of each mesh unit under the temperature field and the fatigue damage value under the vibration field, and then take the reciprocal to obtain the life of each mesh unit under the temperature-vibration coupling environment. According to the life of each grid unit in the temperature-vibration coupling environment, combined with the equivalent stress value of each grid unit in the temperature field and the equivalent stress value in the vibration field, the reliability analysis of the product can be carried out.

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