Reliability numerical analysis method for strong coupling in thermal-vibrational environment

Abstract

The application discloses a kind of reliability numerical analysis methods of strong coupling in temperature-vibration environment, comprising: the product to be analyzed is modeled three-dimensionally, the model built is divided into several grid units, and the information of each grid unit is exported;The random vibration load to be added is preprocessed, and the random vibration load excitation in time domain is obtained;At the same time, the temperature environment load to be added is preprocessed, and the temperature variation function of the physical parameters of structure field under temperature cycle condition in time domain is obtained;Based on the information of each grid unit, the random vibration load excitation and the temperature variation function of the physical parameters of structure field, through temperature-structure field coupling and vibration-structure field coupling, the analysis of temperature-vibration strong coupling field is carried out using the matrix iterative calculation mode, and the strain value and stress value are obtained;According to the strain value, the fatigue damage value and life of product are calculated, and the reliability numerical analysis under temperature-vibration coupling environment is realized in combination with stress value.The method has the advantages of high efficiency and high accuracy.

Description

Technical Field

[0001] The present invention belongs to the technical field of reliability analysis, and in particular relates to a strong-coupling reliability numerical analysis method under 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 even completely fail to work.

[0003] According to statistics, 55% of electronic component failures are due to temperature fluctuations, 20% to vibration and shock, 19% to moisture, and 6% to dust. This indicates that under operational or environmental stress, failures are inevitably caused by corresponding mechanisms, with temperature and vibration being the dominant factors. Furthermore, when combined with temperature and random vibration loading, these two factors often exhibit a certain coupling relationship, leading to significant errors in conventional reliability analysis methods for electronic products compared to actual conditions.

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

[0005] However, existing finite element simulation technology cannot effectively reflect the internal coupling mechanism between temperature and random vibration loads during coupling. Furthermore, the temperature load in the time domain and the random vibration load in the frequency domain cannot be applied simultaneously in a transient state, thus failing to match the actual working environment, further reducing accuracy. Furthermore, existing finite element simulation software, due to its complex and comprehensive computational processing system, has a slightly poor computational specificity, often requiring a significant amount of additional computational work and resulting in a significant time-consuming process. Summary of the Invention

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

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

[0008] Step 1: Create a 3D model of the product to be analyzed, divide the model into several grid cells, and export the information of each grid cell;

[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 cell, random vibration load excitation, and the temperature-dependent function of the physical parameters of the structural field, the temperature-vibration strong coupling field is analyzed by matrix iterative calculation through temperature-structure field coupling and vibration-structure field coupling to obtain the strain and stress values ​​of each grid cell;

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

[0012] Beneficial effects of the present invention:

[0013] The present invention provides a reliability numerical analysis method for strong coupling under a temperature-vibration environment. First, a three-dimensional model is performed on the product to be analyzed and the model is divided into a number of grid units. Then, the vibration and temperature cycle loads to be added are pre-processed to obtain the temperature-varying 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 based on 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, this method converts the temperature cycle and random vibration load into the excitation and temperature-varying parameters in the time domain, performs a more realistic transient analysis of the temperature cycle and 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 temperature-vibration coupling conditions. Compared with the existing finite element analysis method, this method 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 This is a flow chart of a numerical analysis method for reliability of strong coupling under a temperature-vibration environment provided by an embodiment of the present invention;

[0016] Figure 2 1 is a flow chart of another method for numerical analysis of reliability with strong coupling in a temperature-vibration environment provided by an embodiment of the present invention;

[0017] Figure 3 This 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 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 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 by an embodiment of the present invention. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0024] Please see the joint Figure 1 and Figure 2 , Figure 1 1 is a flow chart of a numerical analysis method for reliability under a temperature-vibration environment with strong coupling 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: Create a 3D model of the product to be analyzed, divide the model into several grid cells, and export the information of each grid cell.

[0026] First, obtain the structural parameters of the product to be analyzed, and perform 3D modeling in the modeling software based on the structural parameters;

[0027] Specifically, taking the Through Silicon Via (TSV) structure as an example, parameters such as the thickness and radius of the upper and lower RDL layers, the diameter and height of the copper pillars, the thickness and height of the silicon dioxide buffer layer and the silicon substrate layer can be obtained, and a three-dimensional model of the TSV can be established using three-dimensional modeling software.

[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 therefore also has parameters such as the Poisson's ratio corresponding to the material. Based on the shape of the grid unit, 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 fixed model bottom 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 pre-processed and the random vibration power spectrum signal in the frequency domain is converted to the time domain using the inverse Fourier transform. The formula for 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 time domain random vibration load signal is multiplied by the model mass to obtain the force load excitation, which is used as the random vibration load excitation in the time domain.

[0041] After Fourier inverse transform processing, the time domain random vibration load signal is obtained as follows: Figure 4 As shown, the vertical axis represents acceleration g. To better meet the application analysis of force fields, the time-domain random vibration load signal data is multiplied by the model mass to obtain the force load excitation. This achieves the conversion of random vibration loads in the frequency domain into force load excitation in the time domain.

[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 change 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 related to temperature, thereby obtaining the temperature-varying 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).

[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] Where A n is the interpolation coefficient, and [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 cell, random vibration load excitation, and temperature-dependent functions of the physical parameters of the structural field, the temperature-vibration strong coupling field is analyzed by matrix iterative calculation through temperature-structure field coupling and vibration-structure field coupling to obtain the strain and stress values ​​of each grid cell.

[0053] Optionally, as an implementation method, this embodiment can input relevant data into the MATLAB platform for relevant calculation and analysis.

[0054] In this example, after determining the material's temperature-dependent properties, a temperature-dependent iteration method is employed at each time step to account for the nonlinear effects of the equations. The temperature field is calculated for the current time step, with time t as the unit. Simultaneously, information such as the stiffness matrix of each mesh element is also time-step dependent. Through an iterative solution, the stress and strain calculations for each mesh element are achieved.

[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, stress and strain values ​​of each grid unit starting from number 1 at the first second, i.e. t = 1s, are solved. After completing the solution of the temperature field distribution, stress and strain values ​​of all units in a time step, the solution of each item in the next time step is 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, completing the entire process of solving stress and strain using numerical analysis.

[0056] See Figure 8 , Figure 8 is a flow chart of solving stress and strain using a numerical analysis method provided by an embodiment of the present invention, and 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 cells over time. The heat conduction equation is shown as follows:

[0060]

[0061] Where ρ represents the material density (unit: kg / m 3 ), c represents the specific heat capacity (unit: J / (kg·K)), T represents the 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 cell at 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 ​​can be obtained, including the thermal expansion coefficient, thermal conductivity and Young's modulus.

[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 the derivative matrix B of the shape function used to describe the relationship between strain and unit displacement can also 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 cell, and B represents the derivative matrix of the shape function of the grid cell.

[0072] 34) Based on the physical parameter values ​​of the structural field and the material stiffness matrix, the stress and strain of each grid cell under the temperature field are calculated. At the same time, combined with the random vibration load excitation, the stress and strain of each grid cell under the vibration field are calculated, and the corresponding strain and stress values ​​of each grid cell 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 cell, 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] Where 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 based on the thermal strain value under the temperature field. The calculation formula is:

[0078] σ1=D·ε1;

[0079] Where σ1 represents the thermal stress value under the 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 dynamic equations are used to calculate the displacement vector, thereby obtaining 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, D k represents the stiffness matrix of each mesh element, and u(t) represents the displacement vector, which is also the displacement matrix to be solved. Once the mesh element 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) Calculate the strain value under the vibration field according to the displacement matrix. The calculation formula is:

[0088] ε2=B*U;

[0089] Where 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 based on the strain value under the vibration field. The calculation formula is:

[0091] σ2=D·ε2;

[0092] Where, 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 grid cell under the temperature field and the vibration field, the equivalent stress value and the equivalent strain value of the corresponding grid cell are updated.

[0094] Specifically, the thermal strain values ​​under the temperature field obtained in step 34a) include normal strain values ​​and shear strain values, and 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] Regarding the specific implementation scheme of calculating equivalent stress and equivalent strain 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 in 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 cell, and calculate the product life based on the fatigue damage value. Combined with the stress value, 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. This 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 based on the empirical value of the material. 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, this embodiment first converts the obtained life value into a damage value so that it can 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 the 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 relationship between the total strain amplitude and life, the expression is as follows:

[0112]

[0113] Where Δε t is the total strain amplitude, which can be brought 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] By using 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) Using the Palmgren-Miner law, the fatigue damage value of each grid unit under the temperature field and the fatigue damage value under the vibration field are added, and the inverse is taken to obtain the life of each grid unit under the temperature-vibration coupling environment.

[0117] Specifically, this embodiment calculates the fatigue damage value D of each grid unit under random vibration load. 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 lifespan of each mesh cell under a temperature-vibration coupling environment can be used to directly reflect the reliability of that location. Furthermore, the total equivalent stress value for each mesh cell under a temperature-vibration coupling environment can be derived based on the equivalent stress values ​​under temperature and vibration fields. This allows us to identify hazardous locations based on points with large total stress values, further enabling reliability analysis.

[0120] The present invention provides a numerical analysis method for reliability of strong coupling under temperature-vibration environment. Starting from the perspective of coupling mechanism, this method 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 and 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, this method has the advantages of high efficiency and high precision.

[0121] This method can firstly perform reliability analysis on electronic products under temperature-vibration coupling conditions under highly unified time domain conditions, eliminating the need for prestressing and resolving the problem of being unable to perform time-domain transient analysis on vibration loads in the frequency domain within simulation software. Furthermore, in a unified time domain, temperature changes can cause changes in parameters such as the material's Young's modulus, thermal conductivity, and thermal expansion coefficient, thereby affecting the rigidity of the structure and causing the structure's natural frequency to change. Therefore, when random vibration loads are applied to the structure, the effects of the random vibration loads will also change due to the change in the natural frequency. The above-mentioned temperature-dependent parameter changes are also uniformly analyzed in the time domain, thus enabling a reliability analysis closer to actual application environments through the influence relationship between temperature, structure, and vibration field. Furthermore, the numerical analysis calculations performed directly on the temperature-vibration matrix iteration platform using the MATLAB platform have stronger directivity, making them more efficient and accurate than analysis performed directly within finite element simulation software. Practical examples have shown that the strong coupling numerical analysis method of the present invention improves accuracy by 19% and reduces time by 13% compared to traditional finite element analysis methods.

[0122] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A numerical analysis method for reliability of strong coupling under temperature and vibration environment, characterized by: include: Step 1: Create a 3D model of the product to be analyzed, divide the model into several grid cells, and export the information of each grid cell; 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: 31) Initialize the time step and the temperature field distribution, equivalent stress value and equivalent strain value of each grid cell; 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) obtaining the physical parameter value of the structural field of each grid cell according to the temperature field distribution of each grid cell and the temperature variation function of the physical parameter of the structural field; And calculate the material stiffness matrix; 34) Based on the physical parameter values ​​of the structural field and the material stiffness matrix, the stress and strain of each grid cell under the temperature field are calculated. At the same time, combined with the random vibration load excitation, the stress and strain of each grid cell under the vibration field are calculated, and the strain value and stress value of each grid cell under the temperature field and the vibration field are obtained accordingly; 35) updating the equivalent stress value and equivalent strain value of the corresponding grid cell based on the strain value and stress value of each grid cell under the temperature field and the vibration field; 36) Increment 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; Step 4: Calculate the fatigue damage value of the product based on the strain value of each grid unit, calculate the product life based on the fatigue damage value, and realize the numerical analysis of reliability under the temperature-vibration coupling environment in combination with the stress value.

2. The method for numerical analysis of reliability of strong coupling under temperature-vibration environment according to claim 1, 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. The method for numerical analysis of strong coupling reliability under temperature-vibration environment according to claim 1, 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; this includes: 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. The method for numerical analysis of reliability of strong coupling under temperature-vibration environment according to claim 1, 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 cycling conditions; 2b) under the temperature cycle condition, using an interpolation method to express the physical parameters of the structural field as a function related to temperature, 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 method for numerical analysis of reliability of strong coupling under temperature-vibration environment according to claim 4, characterized in that: In step 32), the temperature field distribution of each grid cell is calculated using the heat conduction equation; wherein the heat conduction equation is expressed as: ； Where, represents the material density, represents the specific heat capacity, Indicates temperature T The partial derivative with respect to time, represents the temperature increment in adjacent time steps, represents thermal conductivity, Represents the heat source inside the grid cell.

6. The method for numerical analysis of reliability of strong coupling under temperature-vibration environment according to claim 4, characterized in that: In step 33), the calculation formula of the material stiffness matrix is: ； Where, represents the material stiffness matrix, represents Young's modulus, represents Poisson's ratio.

7. The method for numerical analysis of strong coupling reliability under temperature-vibration environment according to claim 6, characterized in that: In step 34), the stress and strain calculation under the temperature field is performed on each grid cell, 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: ； Where, represents the thermal strain value under the temperature field, represents the coefficient of thermal expansion, Indicates the current temperature. represents the reference temperature, represents the identity matrix; The corresponding thermal stress value is calculated according to the thermal strain value under the temperature field and the material stiffness matrix. The calculation formula is: ； Where, represents the thermal stress value under the temperature field, represents the material stiffness matrix.

8. The method for numerical analysis of reliability of strong coupling under temperature-vibration environment according to claim 6, characterized in that: In step 34), the stress and strain calculations under the vibration field are performed on each grid cell, specifically including: According to the random vibration load excitation, the displacement vector is calculated using the dynamic equations to obtain the displacement matrix; wherein the dynamic equations are expressed as: ； Where, represents the mass matrix determined by the shape function, represents the acceleration vector, represents the damping matrix determined by the shape function, represents the velocity vector, represents the displacement vector, represents random vibration load excitation, Represents the stiffness matrix of each grid element, which is calculated from the material stiffness matrix. The calculation formula is: ； Where, Expressed as the volume of the grid cell, The derivative matrix of the shape function representing the grid cell; The strain value under the vibration field is calculated according to the displacement matrix, and the calculation formula is: Where, represents the strain value under the vibration field, represents the displacement matrix; The corresponding stress value is calculated according to the strain value under the vibration field, and the calculation formula is: ； Where, represents the stress value under the vibration field, represents the material stiffness matrix.

9. The method for numerical analysis of reliability of strong coupling under temperature-vibration environment according to claim 8, 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; The Palmgren-Miner law is used to add the fatigue damage value of each grid element under the temperature field and the fatigue damage value under the vibration field, and then take the inverse to obtain the life of each grid element under the temperature-vibration coupling environment. Based on the life of each grid unit in a 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 performed.

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