A method for predicting damage evolution and performance degradation of adhesive interface under random load

Abstract

The application discloses a method for predicting damage evolution and performance degradation of a bonding interface under random load, and belongs to the field of bonding interface damage prediction under random load. First, random load signals in the cutting process of a bonding component are collected, and the random load signals are subjected to detrending treatment and feature segment signals are extracted. Second, the pre-simulation results of the bonding component are processed to obtain the distribution range of the stress amplitude and frequency of the bonding interface. Third, vibration load experiments are conducted on standard butt bonding samples and standard shear bonding samples to obtain S-N fatigue life curves in the normal stress direction and the shear stress direction, and the cohesive force parameters of the bonding interface after degradation under different damage degrees. Finally, a simulation model for predicting the damage evolution and performance degradation of the bonding interface of the bonding component is constructed to predict the damage of the bonding interface. The application can effectively predict the damage evolution and residual mechanical performance of the bonding interface after high-frequency random vibration load, improve the calculation efficiency, and has guiding significance.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of adhesive interface damage prediction under random load, and relates to a method for predicting adhesive interface damage evolution and performance degradation under random load, in particular to a method for predicting adhesive interface damage evolution and performance degradation under random load based on ABAQUS secondary development. BACKGROUND

[0002] Nowadays, under the driving of high-end manufacturing lightweight demand, adhesive technology is widely used in aerospace, aviation, electronics and other objects due to its high specific strength and uniform stress distribution. In the field of precision manufacturing, in order to ensure the machining accuracy of the adhesive component, the preparation process of first bonding and then cutting is usually adopted. However, the random cutting load generated in the cutting process will cause damage accumulation of the adhesive interface, thereby affecting the mechanical properties and structural reliability of the adhesive component. Therefore, it is of great significance to optimize the machining parameters and improve the reliability of the adhesive component by deeply studying this problem.

[0003] At present, the research on adhesive interface damage evolution under random load is relatively less, and the general interface mechanical property degradation under the action of heat and aging is more, such as the solid rocket engine adhesive interface aging and creep damage test method and coupling model disclosed in Chinese invention patent (202410863286.X); and the interface fatigue life prediction model under low frequency constant amplitude load, such as the multi-axial variable amplitude thermal mechanical fatigue life prediction method based on critical interface damage disclosed in Chinese invention patent (201911338597.X), and most of them do not consider the mechanical property degradation of the interface under the action of alternating cyclic load.

[0004] Therefore, a method for predicting adhesive interface damage evolution and performance degradation under random load is needed, which can be applied to high frequency random load and consider the mechanical property degradation of the interface. SUMMARY

[0005] In view of the problems existing in the prior art, the application provides a method for predicting adhesive interface damage evolution and performance degradation under random load. The application can predict the damage degree of the adhesive interface in the whole random loading process by inputting the characteristic segment signal in the finite element model.

[0006] To achieve the above purpose, the technical scheme adopted by the application is as follows:

[0007] A method for predicting adhesive interface damage evolution and performance degradation under random load, comprising the following steps:

[0008] Firstly, the random load signal in the cutting process of the adhesive component is collected, the random load signal is de-trended and the characteristic segment signal is extracted, specifically:

[0009] Step 1.1, the original random load signals in three coordinate directions are obtained by collecting the random load signals in three coordinate directions during the cutting process through a three-coordinate dynamometer;

[0010] Step 1.2, the original random load signals in three coordinate directions obtained in step 1.1 are respectively subjected to de-trend data processing to solve the zero drift problem occurring in the collection process;

[0011] Step 1.3, feature segment signals are extracted from the three coordinate direction random load signals obtained after de-trend processing in step 1.2. Since the tool cutting path is in a form of cyclic repetition, only the random load signal in one cycle needs to be extracted as a feature segment signal.

[0012] Secondly, since the stress distribution of the bonding interface cannot be directly measured by the three-coordinate dynamometer, a pre-simulation model of the bonding component based on the measured random load signal as the boundary condition is established to obtain the stress response of the bonding interface. The damage degradation of the bonding interface is not considered in this simulation. The pre-simulation results of the bonding component are analyzed in time and frequency domains by rainflow counting method and power spectral density respectively to obtain the distribution range of the stress amplitude and frequency of the bonding interface. Specifically:

[0013] Step 2.1, pre-processing of the pre-simulation model of the bonding component, specifically:

[0014] Step 2.1.1, drawing the geometric model of the bonding component;

[0015] Step 2.1.2, meshing the geometric model of the bonding component obtained in step 2.1.1 to obtain a mesh model;

[0016] Step 2.1.3, defining the material properties of the mesh model obtained in step 2.1.2, setting the bonding interface as a cohesive element and using a bilinear cohesive constitutive model, and using a solid element for the component matrix part;

[0017] Step 2.1.4, creating an analysis step and setting the required output variables;

[0018] Step 2.1.5, setting constraints and contacts according to the stress condition of the actual machining process of the bonding component;

[0019] Step 2.1.6, setting the boundary conditions of the mesh model and applying the feature segment signal as the load condition to obtain the pre-simulation model of the bonding component.

[0020] Step 2.2, post-processing of the pre-simulation model of the bonding component to obtain the simulation results;

[0021] Step 2.3, the rainflow counting method statistics and power spectral density analysis are carried out on the simulation results of the bonding component pre-simulation model in step 2.2, and the distribution ranges of the stress amplitude and frequency of the bonding interface are obtained respectively.

[0022] Step 3, according to the distribution ranges of the stress amplitude and frequency of the bonding interface obtained in step 2, vibration load experiments of standard butt bonding samples and standard shear bonding samples are carried out, and S-N fatigue life curves in the direction of normal stress and in the direction of shear stress are obtained respectively, and the cohesion parameters of the bonding interface after degradation under different damage degrees are obtained, specifically:

[0023] Step 3.1, since the random load signal belongs to a high-frequency cutting force signal, referring to the adhesive tensile and shear strength determination standards GB / T 6329-1996 and GB / T 7124-2008, the application designs standard butt bonding samples and standard shear bonding samples which can be used with a high-frequency vibration test bench, and all the samples are prepared according to the specified bonding process;

[0024] Step 3.2, fatigue tests of the standard butt bonding samples and the standard shear bonding samples under different stress amplitudes are carried out respectively, specifically:

[0025] Step 3.2.1, according to the stress amplitude distribution range obtained by the rainflow counting method, the stress amplitude is divided into several stress amplitude gradients, and the normal stress direction and the shear stress direction are separated;

[0026] Step 3.2.2, according to the power spectral density analysis results, the frequency with the largest energy proportion is selected as the fatigue loading frequency, and the normal stress direction and the shear stress direction are separated;

[0027] Step 3.2.3, according to the experimental conditions set in steps 3.2.1 and 3.2.2, vibration fatigue tests of the standard butt bonding samples and the standard shear bonding samples are carried out, and S-N fatigue life curves in the direction of normal stress and in the direction of shear stress are drawn respectively.

[0028] Step 3.3, the cohesion parameters of the standard butt bonding samples and the standard shear bonding samples after degradation under different damage degrees are tested respectively, specifically:

[0029] Step 3.3.1, according to the stress amplitude distribution range obtained by the rainflow counting method, the stress amplitude with the largest proportion in the direction of normal stress and in the direction of shear stress is selected respectively, and the stress amplitude and the frequency selected in step 3.2.2 are used as the vibration loading conditions;

[0030] Step 3.3.2, based on Miner theory and S-N fatigue life curve, proposes a method of presetting damage to test the degraded cohesive force parameters of standard butt adhesive specimens and standard shear adhesive specimens under different damage levels. The Miner theory calculation formula is:

[0031]

[0032] wherein, is the actual cycle number under the stress level; is the fatigue life corresponding to the stress level, obtained from the S-N fatigue life curve; represents the cumulative damage value, when the fatigue failure occurs; represents the stress level number, is the total number of stress levels;

[0033] Step 3.3.3, the degraded cohesive force parameters of standard butt adhesive specimens under different damage levels are tested, specifically:

[0034] Step 3.3.3.1, preset the damage of standard butt adhesive specimens under different cycle numbers at the same stress amplitude and frequency;

[0035] Step 3.3.3.2, the residual mechanical properties of standard butt adhesive specimens with different damage levels are tested to obtain the normal stress direction cohesive force parameters of the degraded adhesive interface.

[0036] Step 3.3.4, the degraded cohesive force parameters of standard shear adhesive specimens under different damage levels are tested, specifically:

[0037] Step 3.3.4.1, preset the damage of standard shear adhesive specimens under different cycle numbers at the same stress amplitude and frequency;

[0038] Step 3.3.4.2, the residual mechanical properties of standard shear adhesive specimens with different damage levels are tested to obtain the shear stress direction cohesive force parameters of the degraded adhesive interface.

[0039] Step 4, according to the normal stress direction S-N fatigue life curve and the shear stress direction S-N fatigue life curve obtained in step 3, as well as the normal stress direction cohesive force parameters and the shear stress direction cohesive force parameters of the degraded adhesive interface under different damage levels, a simulation model for predicting the interface damage evolution and performance degradation of the adhesive component is constructed to predict the adhesive interface damage, specifically:

[0040] Step 4.1, the simulation model for predicting the interface damage evolution and performance degradation of the adhesive component is preprocessed, specifically: ​

[0041] Step 4.1.1, define the material properties of the grid model in step 2.1.2, the bonding interface is set as a cohesive element, and a bilinear cohesive constitutive model is used, while the component substrate part is set as a solid element. At the same time, the field variables The number of definitions And Damage value in the direction of normal stress and shear stress, respectively;

[0042] Step 4.1.2, create an analysis step and set the required output variables;

[0043] Step 4.1.3, set the constraints and contacts according to the stress situation of the actual processing process of the bonded component;

[0044] Step 4.1.4, set the boundary conditions of the grid model, and use the characteristic segment signal as the load application condition.

[0045] Step 4.2, according to the method of predicting the damage evolution and performance degradation of the bonding interface under random load based on ABAQUS secondary development, the interface damage calculation is carried out, which is specifically as follows:

[0046] Step 4.2.1, a new damage calculation method is proposed, which is called "small interval rainflow counting damage calculation" in the implementation process of the simulation model of interface damage evolution and performance degradation prediction of bonded components. According to the characteristic segment signal time size and load frequency setting, the time interval of small interval rainflow counting method is Second;

[0047] Step 4.2.2, trigger small interval rainflow counting statistics every Second, the stress amplitude of the material integration point of the cohesive element of the bonding interface is counted;

[0048] Step 4.2.3, the stress-time history data in the direction of normal stress is counted by rainflow counting method;

[0049] Step 4.2.4, based on the Miner theory, the damage in the direction of normal stress is calculated and multiplied by the corresponding amplification coefficient, the addition of the amplification coefficient can realize the prediction of the damage caused by the whole cutting process load through the characteristic segment signal, and the corresponding amplification coefficient is = Total effective cutting time / characteristic segment signal time;

[0050] Step 4.2.5, the stress-time history data in the direction of shear stress is counted by rainflow counting method, and the damage in this interval is calculated. In the local coordinate system of the cohesive element of the bonding interface, there are two directions of shear stress, shear stress-1 and shear stress-2, which are perpendicular to each other, which are specifically:

[0051] Step 4.2.5.1, Rainflow counting statistics for shear stress-1 direction;

[0052] Step 4.2.5.2, Damage for shear stress-1 direction is calculated based on Miner theory and multiplied by the corresponding amplification factor ;

[0053] Step 4.2.5.3, Rainflow counting statistics for shear stress-2 direction;

[0054] Step 4.2.5.4, Damage for shear stress-2 direction is calculated based on Miner theory and multiplied by the corresponding amplification factor .

[0055] Step 4.2.6, After the damage in different directions is calculated, it needs to be calculated step by step. The calculation formula is: . Wherein, is the interval damage value calculated based on the intercell rainflow counting method this time, is the cumulative damage value of the last step, is the updated cumulative damage value;

[0056] Step 4.2.7, The total damage of two shear stress directions is calculated by the formula: . Wherein, is the damage of shear stress-1 direction, is the damage of shear stress-2 direction, is the total damage of shear stress direction;

[0057] Step 4.2.8, The and total damage are respectively assigned to the field variables and , wherein, represents the normal stress direction damage. Through the and field variable value changes, the corresponding cohesive force unit cohesive force parameters are degraded. Wherein, is the damage of normal stress direction, is the total damage of shear stress direction and;

[0058] Step 4.2.9, is the total damage of normal stress and shear stress, and the calculation formula is: ;

[0059] Step 4.2.10, If the current analysis step time + time interval > total time If yes, the simulation ends and goes to step 4.3, otherwise, return to step 4.2.3.

[0060] Step 4.3, post-processing is performed on the adhesive member interface damage model under random load, and the total damage average value or local damage value of the adhesive interface is extracted as an index for evaluating the interface damage condition.

[0061] The beneficial effects of the present application are:

[0062] (1) The model established in the present application can effectively predict the adhesive interface damage evolution process and residual mechanical properties after high-frequency random vibration load;

[0063] (2) The present application predicts the interface damage degree of the whole loading process by using the characteristic segment signal, which effectively improves the calculation efficiency;

[0064] (3) The present application has guiding significance for evaluating the interface damage degree and evolution process under different random vibration loads, analyzing the process parameter sensitivity and optimizing the processing parameters. BRIEF DESCRIPTION OF DRAWINGS

[0065] Figure 1 Fig. 1 is a schematic diagram of the original data collected in the X, Y and Z directions and the results after the trend item processing; Figure 1 Fig. 1(a) is the original data of the X-axis, Figure 1 Fig. 1(b) is the data after the trend item processing, Figure 1 Fig. 1(c) is the original data of the Y-axis, Figure 1 Fig. 1(d) is the data after the trend item processing, Figure 1 Fig. 1(e) is the original data of the Z-axis, Figure 1 Fig. 1(f) is the data after the trend item processing.

[0066] Figure 2 Fig. 2 is a time domain and frequency domain analysis diagram of the pre-simulation results of the adhesive member; Figure 2 Fig. 2(a) is a stress amplitude distribution diagram in the rainflow counting method statistical results, Figure 2 Fig. 2(b) is an amplitude-mean-cycle number three-dimensional column chart in the rainflow counting method statistical results, Figure 2 Fig. 2(c) is a power spectral density PSD curve.

[0067] Figure 3 Fig. 3 is a schematic diagram of a standard butt adhesive sample and a standard shear adhesive sample; Figure 3 Fig. 3(a) is a standard butt adhesive sample, Figure 3 Fig. 3(b) is a standard shear adhesive sample.

[0068] Figure 4 Fig. 4 is a schematic diagram of the amplification coefficient in the secondary development.

[0069] Figure 5For the modeling process of the adhesive interface damage under the random load.

[0070] Figure 6 For the adhesive interface damage simulation cloud picture; Figure 6 (a) in (a) is the stress damage cloud picture of the normal stress direction; Figure 6 (b) in (b) is the stress cloud picture of the shear stress direction; Figure 6 (c) in (c) is the total damage cloud picture.

[0071] Figure 7 For the total damage-time history output curve of the adhesive interface. DETAILED DESCRIPTION

[0072] The present application is further described below in conjunction with the accompanying drawings, and the present application relies on the background of the simulation data of the interface damage evolution of the metal adhesive component under the random cutting load.

[0073] Firstly, the random load signals in the cutting process of the adhesive component are collected, the random load signals are de-trended and the characteristic segment signals are extracted, specifically:

[0074] Step 1.1, the random load signals in three coordinate directions in the cutting process are collected by the three-coordinate dynamometer, and the original random load signals are obtained;

[0075] Step 1.2, the original random load signals in three coordinate directions obtained in step 1.1 are respectively de-trended to solve the zero drift problem in the collection process, and the processing results are as Figure 1 ;

[0076] Step 1.3, the characteristic segment signals are extracted from the three coordinate direction random load signals obtained after de-trended in step 1.2. Since the cutting path of the tool is in a form of cyclic repetition, only the random load signals in one cycle are extracted as the characteristic segment signals.

[0077] Secondly, since the stress distribution of the adhesive interface cannot be directly measured by the three-coordinate dynamometer, a pre-simulation model of the adhesive component based on the measured random load signals as the boundary conditions is needed to obtain the stress response of the adhesive interface, and the damage degradation of the adhesive interface is not considered in this simulation. The rainflow counting method and the power spectral density are respectively used for time domain and frequency domain analysis of the pre-simulation results of the adhesive component to obtain the distribution range of the stress amplitude and frequency of the adhesive interface, specifically:

[0078] Step 2.1, pre-processing is performed on the pre-simulation model of the adhesive component, specifically:

[0079] Step 2.1.1, draw the geometric model of the adhesive component;

[0080] Step 2.1.2, meshing the bonding component geometry model obtained in step 2.1.1 to obtain a mesh model;

[0081] Step 2.1.3, defining the material properties of the mesh model obtained in step 2.1.2, setting the bonding interface as a cohesive force unit and using a bilinear cohesive force constitutive, and the component substrate part using a solid unit;

[0082] Step 2.1.4, creating an analysis step and setting the required output variables;

[0083] Step 2.1.5, setting constraints and contacts according to the stress conditions of the actual processing process of the bonding component;

[0084] Step 2.1.6, setting the boundary conditions of the mesh model, and using the characteristic section signal as the load application condition.

[0085] Step 2.2, post-processing the pre-simulation model of the bonding component to obtain the simulation results;

[0086] Step 2.3, performing rainflow counting and power spectral density analysis on the simulation results of the bonding component pre-simulation model in step 2.2 to obtain the distribution range of the stress amplitude and frequency of the bonding interface, respectively, and the analysis results are as follows Figure 2 Only one shear stress direction is shown here, and the average size is not considered in this method.

[0087] Step 3, according to the distribution range of the stress amplitude and frequency of the bonding interface obtained in step 2, performing vibration load experiments on standard butt bonding samples and standard shear bonding samples to obtain S-N fatigue life curves in the normal stress direction and the shear stress direction, respectively, and the cohesive force parameters after the degradation of the bonding interface under different damage degrees, specifically:

[0088] Step 3.1, since the random load signal belongs to a high-frequency cutting force signal, referring to the adhesive tensile and shear strength determination standards GB / T 6329-1996 and GB / T 7124-2008, the present application designs standard butt bonding samples and standard shear bonding samples which can be used with a high-frequency vibration test bench, all samples are prepared according to the specified bonding process, and the three-dimensional model is as follows Figure 3 ;

[0089] Step 3.2, respectively, fatigue testing of standard butt bonding samples and standard shear bonding samples under different stress amplitudes, specifically:

[0090] Step 3.2.1, according to the stress amplitude distribution range obtained by rainflow counting, divide it into several stress amplitude gradients, and perform separately in the normal stress direction and the shear stress direction;

[0091] Step 3.2.2. According to the power spectral density analysis result, the frequency with the largest energy proportion is selected as the fatigue loading frequency, and the normal stress direction and the shear stress direction are separated for testing;

[0092] Step 3.2.3. According to the experimental conditions set in steps 3.2.1 and 3.2.2, vibration fatigue tests are performed on standard butt joint adhesive samples and standard shear adhesive samples, and normal stress direction S-N fatigue life curves and shear stress direction S-N fatigue life curves are drawn respectively.

[0093] Step 3.3. The degradation of the cohesive force parameters of standard butt joint adhesive samples and standard shear adhesive samples under different damage degrees is tested respectively, specifically as follows:

[0094] Step 3.3.1. According to the stress amplitude distribution range obtained by the rain flow counting method, the stress amplitude with the largest proportion in the normal stress direction and the shear stress direction is selected respectively, and the stress amplitude and the frequency selected in step 3.2.2 are used as the vibration loading conditions;

[0095] Step 3.3.2. Based on the Miner theory and the S-N fatigue life curve, a method of presetting damage is proposed to test the degradation of the cohesive force parameters of standard butt joint adhesive samples and standard shear adhesive samples under different damage degrees, and the Miner theory calculation formula is as follows:

[0096]

[0097] Wherein, is the actual cycle number under the stress level; is the fatigue life under the corresponding stress level, which is obtained from the S-N fatigue life curve; represents the cumulative damage value, fatigue failure occurs; represents the stress level number, is the total stress level number;

[0098] Step 3.3.3. The degradation of the cohesive force parameters of standard butt joint adhesive samples under different damage degrees is tested, specifically as follows:

[0099] ​Step 3.3.3.1, in the pre-simulation results of the bonding component under certain working conditions, 0.5 MPa is the stress amplitude of the main normal stress direction, and according to the fatigue life curve in step 3.2.3, the corresponding fatigue life is 3200000. Referring to the actual number of times of 0.5 MPa stress amplitude appearing in the rain flow counting method, the maximum damage of the bonding interface cohesive element in the entire random process is estimated. Through calculation, the maximum damage is estimated to be 0.25, and then the bonding interface damage preloading under the stress amplitude of 0.5 MPa and the frequency of 850 HZ, the cycle number of 3200000*0.05, 3200000*0.15, 3200000*0.25, and the corresponding damage values of 0.05, 0.15, 0.25 are carried out.

[0100] Step 3.3.3.2, respectively, the standard butt bonding samples under the overloading times of 160000, 480000, 800000 are tested for residual mechanical properties, and the cohesive force parameters of the bonding interface after degradation under different damage degrees in the normal stress direction are obtained.

[0101] Step 3.3.4, the cohesive force parameter test of the standard shear bonding sample after degradation under different damage degrees is carried out, specifically:

[0102] Step 3.3.3.1, in the pre-simulation results of the bonding component under certain working conditions, 0.5 MPa is the stress amplitude of the main normal stress direction, and according to the fatigue life curve in step 3.2.3, the corresponding fatigue life is 3200000. Referring to the actual number of times of 0.5 MPa stress amplitude appearing in the rain flow counting method, the maximum damage of the bonding interface cohesive element in the entire random process is estimated. Through calculation, the maximum damage is estimated to be 0.25, and then the bonding interface damage preloading under the stress amplitude of 0.5 MPa and the frequency of 850 HZ, the cycle number of 3200000*0.05, 3200000*0.15, 3200000*0.25, and the corresponding damage values of 0.05, 0.15, 0.25 are carried out.

[0103] Step 3.3.3.2, respectively, the standard butt bonding samples under the overloading times of 160000, 480000, 800000 are tested for residual mechanical properties, and the cohesive force parameters of the bonding interface after degradation under different damage degrees in the normal stress direction are obtained.

[0104] Step 4, according to the normal stress direction S-N fatigue life curve and the shear stress direction S-N fatigue life curve obtained in step 3, as well as the normal stress direction cohesive force parameters and the shear stress direction cohesive force parameters of the bonding interface after degradation under different damage degrees, a bonding component interface damage evolution and performance degradation prediction simulation model is constructed to predict the bonding interface damage, specifically:

[0105] Step 4.1, the interface damage evolution and performance degradation prediction simulation model of the bonding component is pre-processed, specifically:

[0106] Step 4.1.1, define the material properties of the grid model in step 2.1.2, set the bonding interface as cohesive force unit, and use bilinear cohesive force constitutive, while the component matrix part uses solid element. At the same time, the number of field variables is set, and and are defined respectively as the damage values in the direction of normal stress and shear stress;

[0107] Step 4.1.2, create analysis step and set the required output variables;

[0108] Step 4.1.3, set constraints and contacts according to the stress situation of the actual processing process of the bonding component;

[0109] Step 4.1.4, set the boundary conditions of the grid model, and use the characteristic segment signal as the load application condition.

[0110] Step 4.2, according to the bonding interface damage evolution and performance degradation prediction method under the action of random load based on ABAQUS secondary development, the interface damage calculation is carried out, specifically:

[0111] Step 4.2.1, a new damage calculation method is proposed, which is based on Miner theory and S-N fatigue life curve, and is called "small interval rain flow counting method damage calculation". According to the characteristic segment signal time size and load frequency setting, the time interval of small interval rain flow counting method is seconds;

[0112] Step 4.2.2, trigger small interval rain flow counting statistics every seconds, and count the stress amplitude of the material integration point of the cohesive force unit of the bonding interface;

[0113] Step 4.2.3, the stress-time history data in the direction of normal stress is counted by rain flow counting method;

[0114] Step 4.2.4, calculate the damage in the direction of normal stress based on Miner theory and multiply the corresponding amplification coefficient, the addition of amplification coefficient can realize the prediction of damage caused by the whole cutting process load through the characteristic segment signal, the corresponding amplification coefficient = total effective cutting time / characteristic segment signal time, the amplification principle diagram is as Figure 4 ;

[0115] Step 4.2.5: Perform rainflow counting on the stress-time history data in the shear stress direction and calculate the damage in this interval. In the local coordinate system of the cohesive unit at the adhesive interface, there are two shear stress directions, shear stress-1 and shear stress-2, which are perpendicular to each other, specifically:

[0116] Step 4.2.5.1: Perform rainflow counting statistics on the shear stress in the -1 direction;

[0117] Step 4.2.5.2: Calculate the damage in the shear stress -1 direction based on Miner's theory, and multiply by the corresponding amplification factor. ;

[0118] Step 4.2.5.3: Perform rainflow counting statistics on the shear stress in the -2 direction;

[0119] Step 4.2.5.4: Calculate the damage in the -2 direction of shear stress based on Miner's theory, and multiply by the corresponding amplification factor. .

[0120] Step 4.2.6: After calculating the damage in different directions, it is necessary to perform a progressively cumulative calculation. The calculation formula is as follows: .in, The interval damage values ​​calculated based on the inter-interval rainflow counting method are used in this study. The cumulative damage value from the previous step, This is the updated cumulative damage value;

[0121] Step 4.2.7, for the total damage in both shear stress directions Through the formula: Calculation. Among them, Damage in the shear stress-1 direction Damage in the shear stress -2 direction Total damage in the direction of shear stress;

[0122] Step 4.2.8, for Total damage Assign values ​​to the field variables respectively and ,in, This indicates damage in the direction of normal stress. (Through...) and Changes in field variable values ​​degrade the cohesive parameters of the corresponding cohesive elements. Among them, Damage is in the direction of normal stress. The total damage in the direction of shear stress;

[0123] Step 4.2.9, The total damage from normal stress and shear stress is calculated using the following formula: ;

[0124] Step 4.2.10, if the current analysis step time +Time interval Total Time If the simulation ends, proceed to step 4.3; otherwise, return to step 4.2.3.

[0125] Step 4.3 involves post-processing the interface damage model of the bonded component under random loads, extracting the total average damage value or local damage value of the bonded interface as an indicator for evaluating the interface damage. Figure 5 This describes the process of modeling damage at the adhesive interface under random loading. Figure 6 For simulation cloud map of adhesive interface damage, Figure 7 This is the output curve of the total damage history of the bonding interface.

[0126] The embodiments described above are merely illustrative of implementation methods of the present invention and should not be construed as limiting the scope of the invention. Those skilled in the art can make variations and improvements to the interface damage evolution and performance degradation prediction methods without departing from the concept of the present invention, including but not limited to adhesive interfaces; these all fall within the protection scope of the present invention.

Claims

1. A method for predicting damage evolution and performance degradation of bonded interfaces under random loading, characterized in that, The method comprises the following steps: The first step is to collect random load signals in the cutting process of the bonding member, to remove the trend items of the random load signals, and to extract characteristic segment signals; The second step is to respectively analyze the time domain and the frequency domain of the pre-simulation results of the bonding member by using the rainflow counting method and the power spectral density, so as to obtain the distribution range of the stress amplitude and the frequency of the bonding interface; The third step is to perform vibration load experiments on standard butt joint bonding samples and standard shear bonding samples according to the distribution range of the stress amplitude and the frequency of the bonding interface obtained in the second step, to respectively obtain the S-N fatigue life curves in the normal stress direction and the S-N fatigue life curves in the shear stress direction, and to obtain the cohesion parameters of the bonding interface after degradation under different damage degrees; The fourth step is to construct a bonding member interface damage evolution and performance degradation prediction simulation model according to the S-N fatigue life curves in the normal stress direction and the S-N fatigue life curves in the shear stress direction obtained in the third step, and the normal stress direction cohesion parameters and the shear stress direction cohesion parameters of the bonding interface after degradation under different damage degrees, and to perform bonding interface damage prediction.

2. The method of claim 1, wherein, The first step specifically comprises: Step 1.1, collecting random load signals in three coordinate directions in the cutting process by using a three-coordinate dynamometer to obtain original random load signals; Step 1.2, respectively removing the trend data of the original random load signals in the three coordinate directions obtained in step 1.1 to solve the zero drift problem occurring in the collection process; Step 1.3, extracting characteristic segment signals from the random load signals in the three coordinate directions obtained after the trend item processing in step 1.2; only the random load signals in one cycle are extracted as characteristic segment signals.

3. The method of claim 2, wherein, The second step specifically comprises: Step 2.1, pre-processing the pre-simulation model of the bonding member, specifically comprising: Step 2.1.1, drawing a geometric model of the bonding member; Step 2.1.2, dividing the geometric model of the bonding member into a grid model; Step 2.1.3, defining the material properties of the grid model, setting the bonding interface as an internal cohesion unit, and adopting a bilinear internal cohesion constitutive relation, and adopting a solid unit for the component matrix part; Step 2.1.4, creating an analysis step and setting the required output variables; Step 2.1.5, setting constraints and contacts according to the stress conditions in the actual processing process of the bonding member; Step 2.1.6, setting the boundary conditions of the grid model, and taking the characteristic segment signals as the load application conditions to obtain the pre-simulation model of the bonding member; Step 2.2, post-processing the pre-simulation model of the bonding member to obtain simulation results; Step 2.3, performing rainflow counting method statistics and power spectral density analysis on the simulation results of the pre-simulation model of the bonding member to respectively obtain the distribution range of the stress amplitude and the frequency of the bonding interface.

4. The method of predicting damage evolution and performance degradation of a bonded interface under random loading according to claim 3, characterized in that, The third step specifically comprises: Step 3.1, designing standard butt joint bonding samples and standard shear bonding samples which can be used with a high-frequency vibration test bench; Step 3.2, respectively performing fatigue tests on the standard butt joint bonding samples and the standard shear bonding samples under different stress amplitudes, specifically comprising: Step 3.2.1, according to the stress amplitude distribution range obtained by the rain flow counting method, the stress amplitude gradient is divided into several stress amplitude gradients, and the normal stress direction and the shear stress direction are separated; Step 3.2.2, according to the power spectrum density analysis result, the frequency with the largest energy proportion is selected as the fatigue loading frequency, and the normal stress direction and the shear stress direction are separated; Step 3.2.3, the vibration fatigue test of the standard butt adhesive sample and the standard shear adhesive sample is carried out, and the normal stress direction S-N fatigue life curve and the shear stress direction S-N fatigue life curve are obtained; Step 3.3, respectively, the degradation of the cohesive force parameters of the standard butt adhesive sample and the standard shear adhesive sample under different damage degrees are tested, specifically: Step 3.3.1, according to the stress amplitude distribution range obtained by the rain flow counting method, the stress amplitude with the largest proportion in the normal stress direction and the shear stress direction is selected, and the stress amplitude and the frequency selected in step 3.2.2 are used as the vibration loading conditions; Step 3.3.2, based on the Miner theory and the S-N fatigue life curve, a method of presetting damage is proposed, and the degradation of the cohesive force parameters of the standard butt adhesive sample and the standard shear adhesive sample under different damage degrees is tested; Step 3.3.3, the degradation of the cohesive force parameters of the standard butt adhesive sample under different damage degrees is tested, and the normal stress direction cohesive force parameters of the adhesive interface after degradation are obtained; Step 3.3.4, the degradation of the cohesive force parameters of the standard shear adhesive sample under different damage degrees is tested, and the shear stress direction cohesive force parameters of the adhesive interface after degradation are obtained.

5. The method of predicting damage evolution and performance degradation of bonded interfaces under random loading according to claim 4, characterized in that, In step 3.1, the standard butt adhesive sample and the standard shear adhesive sample are prepared according to the specified adhesive process.

6. The method of predicting damage evolution and performance degradation of bonded interfaces under random loading according to claim 4, characterized in that, In step 3.3.2, the Miner theory calculation formula is: wherein, is actual number of cycles at a stress level; is the fatigue life at the corresponding stress level, obtained from the S-N fatigue life curve; denotes the cumulative damage value, fatigue failure occurs when denotes the stress level number, is the total number of stress levels.

7. The method of claim 4, wherein, In step 3.3, In step 3.3.3, specifically: Step 3.3.3.1, presetting damage to the standard butt adhesive sample under the same stress amplitude and frequency with different cycle times; Step 3.3.3.2, by testing the residual mechanical properties of the standard butt adhesive sample with different damage degrees, the normal stress direction cohesive force parameters of the adhesive interface after degradation are obtained; In step 3.3.4, specifically: Step 3.3.4.1, presetting damage to the standard shear adhesive sample under the same stress amplitude and frequency with different cycle times; Step 3.3.4.2, by testing the residual mechanical properties of the standard shear adhesive sample with different damage degrees, the shear stress direction cohesive force parameters of the adhesive interface after degradation are obtained.

8. The method of predicting damage evolution and performance degradation of a bonded interface under random loading according to claim 7, wherein, The fourth step is specifically: Step 4.1, preprocessing operation is performed on the adhesive component interface damage evolution and performance degradation prediction simulation model, specifically: Step 4.1.1, define the material properties of the grid model in step 2.1.2, the bonding interface is set as a cohesive element, and a bilinear cohesive constitutive is used, and the component matrix part is set as a solid element; At the same time, the field variables need to be set The number of and respectively refer to the damage value in the direction of normal stress and shear stress; Step 4.1.2, create an analysis step and set the required output variables; Step 4.1.3, set the constraints and contacts according to the stress condition of the actual processing process of the adhesive component; Step 4.1.4, set the boundary conditions of the mesh model, and use the characteristic segment signal as the load application condition; Step 4.2, according to the method of predicting the damage evolution and performance degradation of the adhesive interface under the action of random load developed by ABAQUS, the interface damage is calculated; Step 4.3, the interface damage model of the adhesive member under the action of random load is post-processed, and the total damage average or local damage value of the adhesive interface is extracted as an index to evaluate the interface damage.

9. The method of predicting damage evolution and performance degradation of a bonded interface under random loading according to claim 8, wherein, The step 4.2 is specifically: Step 4.2.1, a damage calculation method is proposed. In the implementation process of the simulation model of the damage evolution and performance degradation prediction of the adhesive component interface, the damage calculation based on the Miner theory and the S-N fatigue life curve is carried out every interval. The time interval of the small interval rain flow counting method is seconds according to the characteristic segment signal time size and load frequency setting. Step 4.2.2, the inter-cell rain flow counting statistics is triggered once every second, and the stress amplitude size statistics of the cohesive interface cohesive unit material integration points are performed. Step 4.2.3, the rainflow counting method is used to count the stress-time history data in the normal stress direction; Step 4.2.4, the damage in the normal stress direction is calculated based on the Miner theory and multiplied by the corresponding amplification coefficient; Step 4.2.5, the rainflow counting method is used to count the stress-time history data in the shear stress direction, and the damage in this interval is calculated, in the local coordinate system of the cohesive element in the adhesive interface, there are two directions in the shear stress direction, shear stress-1 and shear stress-2, which are perpendicular to each other, specifically: Step 4.2.5.1, the rainflow counting method is used to count the shear stress-1 direction; Step 4.2.5.2, calculate damage in shear stress-1 direction based on Miner's theory and multiply by the corresponding amplification factor ; Step 4.2.5.3, the rainflow counting method is used to count the shear stress-2 direction; Step 4.2.5.

4. Calculate damage in shear stress-2 direction based on Miner's theory and multiply by the corresponding amplification factor ; Step 4.2.6, after the above damage in different directions is calculated, step-by-step accumulation calculation is required, and the calculation formula is: ; wherein, is the interval damage value calculated this time based on the inter-cell rain flow counting method, is the cumulative damage value of the previous step, is the updated cumulative damage value; Step 4.2.

7. Total damage for two shear stress directions By the formula: Calculation; where, is the damage for shear stress -1 direction, is the damage for shear stress -2 direction, is the total damage for shear stress directions; Step 4.2.8, to and total damage are assigned to the field variables and respectively, where, denotes the damage in the direction of the normal stress; the field variable values of and degrade the cohesion parameters of the corresponding cohesive elements in the direction of the normal stress and shear stress respectively; where, is the damage in the direction of the normal stress, is the total damage in the direction of the shear stress. Step 4.2.9, The total damage and for normal stress and shear stress are calculated as: ; Step 4.2.10, if the current analysis step time + time interval > total time then the simulation ends and goes to step 4.3, otherwise return to step 4.2.

3.

10. The method of predicting damage evolution and performance degradation of a bonded interface under random loading according to claim 9, wherein The step 4.2.4, the corresponding amplification factor = total process effective cutting time / feature segment signal time.

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