A structural dynamics model updating method

Abstract

The application discloses a structural dynamics model correction method, and belongs to the technical field of model correction, which comprises the following steps: S10, establishing a finite element model of a structure, setting correction variables and their value ranges and initial values; S20, comparing modal finite element analysis with experimental test values; S30, if the error between simulation values and test values exceeds the allowed range, repeating S20 and updating the finite element model; S40, updating the finite element model by using the correction result in S30; S50, resetting the correction variables and their ranges and initial values; S60, comparing harmonic response finite element analysis with experimental test values; S70, if the error between simulation values and test values exceeds the allowed range, adjusting the correction variables, repeating S60 until the error meets the requirement; and S80, updating the finite element model and completing the correction. The application simultaneously contains data of multiple excitation points and multiple response points, effectively avoids the model correction result deviation problem caused by only using a single excitation point or a single response point at a time, and improves the reliability and accuracy of the correction result.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of model correction, and more particularly, to a structural dynamics model correction method. BACKGROUND

[0002] In the design and manufacturing process of industrial equipment, vibration problem is always a key factor that cannot be ignored, which is directly related to the service life, operation accuracy and noise control level of the equipment. With the increasing requirement of modern industry on the performance of equipment, dynamics analysis and vibration reduction optimization have become the core link of product structure development. As an important means of evaluating the dynamic characteristics of structure and design scheme, the importance of dynamics finite element analysis is self-evident. However, the accuracy of this method is often restricted by the differences between the model and the actual structure, which mainly come from the simplification of assembly connection mode, the idealization setting of constraint stiffness, the approximate treatment of material constitutive relation and other aspects, resulting in the deviation between the results of finite element analysis and the actual situation, and further affecting the effectiveness of design decision and the optimization of product performance.

[0003] In order to overcome this problem, model correction technology emerges as the times require, and becomes the key way to improve the accuracy of finite element analysis. Model correction not only helps to identify the key parameters that are difficult to measure directly in experiments, such as stiffness, damping and equivalent concentrated mass distribution, but also effectively compensates for the errors introduced by model simplification, so as to improve the reliability of simulation results. The importance of this technology lies in that it makes the prediction based on finite element analysis closer to the actual observation value, reduces the number of design iterations, speeds up the product development cycle and reduces the research and development cost.

[0004] The research on model updating method has always been a hot topic in the field of dynamics and engineering applications. Early researches mainly focused on the accuracy improvement of model natural frequency. Through direct or indirect updating methods, how to more accurately reflect the dynamic characteristics of the structure was explored. For example, the research on composite structures showed that accurate model updating was essential to improve the accuracy of finite element models. Scholars such as Qin Xianrong and Wei Sha realized the effective updating of complex systems such as tower cranes and butt-jointed cylindrical shell structures through response surface method and other surrogate model techniques, improving the prediction accuracy of natural frequencies. With the deepening of research, people realized that it was not enough to only focus on natural frequency, the size of the vibration response was also important. Therefore, complete model updating should consider both aspects to ensure that the model accurately reflects the behavior of the actual structure under a wider range of dynamic conditions. Some researches combined substructure with finite element model and applied experimental design method to realize accurate updating of cable-stayed suspension combined model bridge, not only improving the prediction accuracy of natural frequency, but also optimizing the prediction of vibration response. Some researches used neural network method to update the torsional spring constant of simply supported beam, and at the same time predicted the static and dynamic response, showing the potential of model updating technology in complex structures.

[0005] Despite the many advances, existing model updating methods still face challenges when dealing with highly nonlinear systems. In such systems, selecting different excitation points or response points for testing may result in completely different model parameters, making the updating process complex and the results unstable. Therefore, exploring a new method that can effectively deal with highly nonlinear system model updating has become an urgent need for current research. SUMMARY

[0006] In order to overcome the shortcomings of the prior art, a structure dynamics model updating method simultaneously contains data of multiple excitation points and multiple response points, effectively avoiding the deviation of model updating results caused by using only a single excitation point or a single response point at a time, and improving the reliability and accuracy of the updating results.

[0007] The technical scheme adopted by the invention to solve its technical problems is: a structure dynamics model updating method, the improvement lies in that the method comprises the following steps:

[0008] S10: Establish a finite element model of the structure and determine the known quantities, select the unknown quantities that have a significant impact on the natural frequency of the structure as the updating variables, and set the value range and initial value of the updating variables;

[0009] S20: Perform modal finite element simulation analysis to obtain the natural frequency simulation value, and compare it with the natural frequency test value;

[0010] S30: If the relative error between the simulation value and the test value of the natural frequency exceeds the allowable error, adjust the correction variable value, and repeat step S20 until the relative error does not exceed the allowable error;

[0011] S40: Update the finite element model using the correction result in S30;

[0012] S50: Based on the updated model, select an unknown quantity that has a significant impact on the structural vibration response as a correction variable, set the value range and initial value of the correction variable;

[0013] S60: Perform harmonic response finite element simulation analysis to obtain the acceleration frequency response function, and calculate the average unit impulse response kinetic energy simulation value, and compare it with the average unit impulse response kinetic energy test value;

[0014] S70: If the relative error between the simulation value and the test value of the average unit impulse response kinetic energy exceeds the allowable range, adjust the correction variable value, and repeat step S60 until the relative error does not exceed the allowable error;

[0015] S80: Update the finite element model using the correction result in S70 to complete the model correction.

[0016] Further, the average unit impulse response kinetic energy is the sum of the vibration velocity signal energy of multiple response points in X, Y, Z three directions under the action of unit impulse excitation at a certain excitation point, and the ratio of the number of response points.

[0017] Further, under the excitation action of excitation point k, the corresponding average unit impulse response kinetic energy calculation formula is:

[0018]

[0019] Where f represents the frequency, h pkx (f) represents the acceleration frequency response function of response point p in the X direction under the excitation action of excitation point k, h pky (f) represents the acceleration frequency response function of response point p in the Y direction under the excitation action of excitation point k, h pkz (f) represents the acceleration frequency response function of response point p in the Z direction under the excitation action of excitation point k, f l is the lower limit value of frequency, f u is the upper limit value of frequency.

[0020] Further, the correction variable selected in step S10 is not selected as a correction variable in step S50.

[0021] Further, the correction variable selected in step S10 includes the density, elastic modulus and constraint stiffness of the component.

[0022] Further, the correction variables selected in step S50 include the structural loss factor and the damping coefficient.

[0023] Further, the model correction target of steps S10-S40 is to make the relative errors between the simulation values and the test values of the first q natural frequencies not exceed the allowed error, which is expressed by the following equation:

[0024]

[0025] wherein, is the simulation value of the first natural frequency, is the test value of the first natural frequency, is the simulation value of the qth natural frequency, is the test value of the qth natural frequency, and v represents the set of correction variables.

[0026] Further, the model correction target of steps S50-S80 is to make the relative errors between the simulation values and the test values of the average kinetic energy of the unit impulse response of all excitation points not exceed the allowed error, which is expressed by the following equation:

[0027]

[0028] wherein, is the simulation value of the average kinetic energy of the unit impulse response of the first excitation point, is the test value of the average kinetic energy of the unit impulse response of the first excitation point, is the simulation value of the average kinetic energy of the unit impulse response of the mth excitation point, is the test value of the average kinetic energy of the unit impulse response of the mth excitation point, u represents the set of correction variables, and m is the number of excitation points.

[0029] Further, the specific steps of step S20 include:

[0030] S201: establishing a modal analysis step in the finite element analysis software, wherein the analysis step is set to calculate the first q natural frequencies;

[0031] S202: solving the finite element model to calculate the simulation values of the first q natural frequencies;

[0032] S203: comparing the simulation values of the natural frequencies with the test values of the natural frequencies.

[0033] Further, the specific steps of step S60 include:

[0034] S601: establishing a harmonic response analysis step in the finite element analysis software, wherein the analysis step is set to calculate the acceleration response function;

[0035] S602: solve the finite element model to calculate the average unit impulse response kinetic simulation value;

[0036] S603: compare the average unit impulse response kinetic simulation value with the average unit impulse response kinetic test value.

[0037] The beneficial effects of the present application are: the data of multiple excitation points and multiple response points are simultaneously contained, the deviation problem of the model correction result caused by using only a single excitation point or a single response point at a time is effectively avoided, and the reliability and accuracy of the correction result are improved. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 The flowchart of the structural dynamics model correction method of the present application is shown in the figure;

[0039] Figure 2 The photo of the assembly collaborative robot-supporting table structure is shown in the figure;

[0040] Figure 3 The flowchart of the verification process of the structural dynamics model correction method of the present application is shown in the figure;

[0041] Figure 4 The first attitude schematic diagram of the assembly collaborative robot is shown in the figure;

[0042] Figure 5 The finite element model of the assembly collaborative robot is shown in the figure;

[0043] Figure 6a The first-order modal shape of the finite element simulation of the assembly collaborative robot-supporting table structure is shown in the figure;

[0044] Figure 6b The second-order modal shape of the finite element simulation of the assembly collaborative robot-supporting table structure is shown in the figure;

[0045] Figure 6c The third-order modal shape of the finite element simulation of the assembly collaborative robot-supporting table structure is shown in the figure;

[0046] Figure 6d The fourth-order modal shape of the finite element simulation of the assembly collaborative robot-supporting table structure is shown in the figure;

[0047] Figure 6e The fifth-order modal shape of the finite element simulation of the assembly collaborative robot-supporting table structure is shown in the figure;

[0048] Figure 6f The sixth-order modal shape of the finite element simulation of the assembly collaborative robot-supporting table structure is shown in the figure;

[0049] Figure 6g The seventh-order modal shape of the finite element simulation of the assembly collaborative robot-supporting table structure is shown in the figure;

[0050] Figure 6h eighth order modal shape of the finite element simulation of the assembly collaborative robot-support table structure;

[0051] Figure 7 comparison chart of average unit impulse response kinetic energy of the first posture of the assembly collaborative robot;

[0052] Figure 8 schematic diagram of the second posture of the assembly collaborative robot;

[0053] Figure 9 comparison chart of average unit impulse response kinetic energy of the second posture of the assembly collaborative robot. DETAILED DESCRIPTION

[0054] The application will be further described below in conjunction with the drawings and embodiments.

[0055] The concept, specific structure and technical effects of the present application will be described clearly and completely in conjunction with the embodiments and drawings, so as to fully understand the purpose, features and effects of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments, and other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative labor are within the scope of protection of the present application. In addition, all the coupling / connection relationships involved in the patent do not mean that the components are directly connected, but that a better coupling structure can be composed by adding or reducing coupling accessories according to the specific implementation. The technical features in the present application can be combined interactively without conflict.

[0056] It should be noted that if the present application embodiments involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement condition, etc. between the components in a certain posture (as shown in the drawings), if the specific posture changes, the directional indications will also change accordingly.

[0057] In addition, if the present application embodiments involve descriptions such as "first", "second", etc., the "first", "second", etc. are only for description purposes, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. Secondly, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of ordinary skilled in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, nor within the scope of protection claimed by the present application.

[0058] The present application will be further described below in conjunction with the drawings.

[0059] Referring to Figure 1 As shown in the drawings, the present application provides a structural dynamics model correction method, which comprises the following steps:

[0060] S10: establishing a finite element model of the structure, determining known quantities, selecting unknown quantities having a significant influence on the natural frequency of the structure as correction variables, and setting the value range and initial value of the correction variables;

[0061] S20: carrying out modal finite element simulation analysis to obtain the simulation value of the natural frequency, and comparing it with the test value of the natural frequency;

[0062] S30: if the relative error between the simulation value and the test value of the natural frequency exceeds the allowable error, adjusting the value of the correction variable, and repeating step S20 until the relative error does not exceed the allowable error;

[0063] S40: updating the finite element model using the correction result in S30;

[0064] S50: based on the updated model, selecting unknown quantities having a significant influence on the vibration response of the structure as correction variables, and setting the value range and initial value of the correction variables;

[0065] S60: carrying out harmonic response finite element simulation analysis to obtain the acceleration frequency response function, and calculating the simulation value of the average unit impulse response kinetic energy, and comparing it with the test value of the average unit impulse response kinetic energy;

[0066] S70: if the relative error between the simulation value and the test value of the average unit impulse response kinetic energy exceeds the allowable range, adjusting the value of the correction variable, and repeating step S60 until the relative error does not exceed the allowable error;

[0067] S80: updating the finite element model using the correction result in S70 to complete the model correction.

[0068] Further, the average unit impulse response kinetic energy is the ratio of the sum of the vibration velocity signal energies of multiple response points in X, Y and Z directions to the number of response points under the action of unit impulse excitation at a certain excitation point.

[0069] Further, under the excitation action of the excitation point k, the corresponding average unit impulse response kinetic energy calculation formula is:

[0070]

[0071] wherein f represents the frequency, h pkx (f) represents the acceleration frequency response function of the response point p in the X direction under the excitation action of the excitation point k, h pky(f) is the acceleration frequency response function of the response point p in the Y direction under the excitation of the excitation point k, h pkz (f) is the acceleration frequency response function of the response point p in the Z direction under the excitation of the excitation point k, f l is the lower limit value of the frequency, f u is the upper limit value of the frequency.

[0072] In the acceleration frequency response function test, the vibration in the X, Y, Z three directions is tested at each response point. When the excitation is performed at the excitation point, the acceleration frequency response functions of the response points in the X, Y, Z directions can be obtained, and the test value of the average unit impulse response kinetic energy corresponding to the excitation point can be calculated by substituting the above formula. When the excitation is performed at other excitation points and substituted into the above formula, the test values of the average unit impulse response kinetic energy corresponding to these excitation points can also be obtained.

[0073] Example one

[0074] The object of this embodiment is an assembly collaborative robot-support table structure, as shown in Figure 2 The assembly collaborative robot is used for the screw locking process on the assembly line, hereinafter referred to as robot. The robot generates a large vibration during the locking process. In order to analyze and evaluate the influence of vibration on the reliability of the robot, an accurate finite element model of the robot structure needs to be established. There are many parameters in the structure that are difficult to measure directly, so the structural dynamics model correction method of the present application is used to realize model correction, as follows.

[0075] The robot is equipped with six motion joints, each joint contains harmonic reducer, drive motor and circuit board components, etc. The mass is large and has a significant impact on the dynamic behavior of the robot. Therefore, in the finite element model, an equivalent concentrated mass is set for each joint, and the size of the equivalent concentrated mass is identified by the structural dynamics model correction method of the present application.

[0076] During the vibration process, the state of the connection contact surface may change, which makes it difficult to determine the effective contact surface and the connection stiffness. Therefore, a spring-damper model containing X, Y, Z three directions is used to simulate the connection characteristics between the robot and the support table. The parameters of the spring-damper model include the spring stiffness and damping coefficient in the X, Y, Z three directions, which are also identified by the structural dynamics model correction method of the present application.

[0077] In addition, the structural damping coefficient of the robot and the support table has a significant impact on the average unit impulse response kinetic energy, which is also identified by the structural dynamics model correction method of the present application.

[0078] As shown in Figure 3As shown, this embodiment selects two postures for the robot model. The first posture is used for model correction to determine three unknowns: equivalent lumped mass, spring stiffness, and structural damping coefficient. The second posture is used to verify the results of the model correction. First, a finite element model of the first posture is established, and the unknowns of the model are corrected using the measured values ​​of the natural frequency and the average unit impulse response kinetic energy obtained under the first posture. Then, a finite element model of the second posture is established, and the three unknowns—equivalent lumped mass, spring stiffness, and structural damping coefficient—are directly corrected using the results of the first posture correction. Finally, the natural frequency and average unit impulse response kinetic energy of the second posture are simulated and calculated. If their simulated values ​​are sufficiently close to the measured values, the result correction is considered correct, thereby verifying the effectiveness of the structural dynamics model correction method of this invention.

[0079] (1) Test of natural frequency and average unit impulse response kinetic energy in the first posture

[0080] The robot's first posture is as follows Figure 4 As shown, the acceleration frequency response function is obtained using the hammer impact test method.

[0081] In the hammer impact test, an excitation point is selected in each of the X, Y, and Z directions, therefore m = 3, as shown below. Figure 4 As shown. Five response points are selected along the robot, so n=5. A triaxial accelerometer is placed at each response point, resulting in a total of 15 acceleration test signal channels.

[0082] Each excitation point was struck sequentially, and the force signal of the hammer and 15 acceleration signals were collected simultaneously to obtain the acceleration frequency response function. Then, the natural frequency was obtained through modal analysis, and the results are shown in Table 1. The average unit impulse response kinetic energy was calculated using the formula for calculating the average unit impulse response kinetic energy, and the results are shown in Table 2.

[0083] Table 1. Test results of natural frequencies in the first posture.

[0084] Modal order Test value of first mode natural frequency (Hz) 1 10.747 2 11.71 3 16.506 4 18.516 5 22.848 6 25.846 7 34.587 8 46.78

[0085] Table 2. Test results of average unit impulse response kinetic energy in the first posture.

[0086] average unit impulse response kinetic test value (m 2 / s 2 )]]> Excitation point one 60.70 Excitation point two 169.42 Excitation point three 49.83

[0087] (2) Model correction for the first attitude

[0088] S10: Establish the finite element model of the structure, determine the known quantities, select the unknown quantities that have a significant impact on the natural frequency of the structure as correction variables, and set the range and initial value of the correction variables.

[0089] Reference Figures 4-5 As shown, step S10 specifically includes:

[0090] S101: According to the first pose of the robot-support table structure, establish their finite element models;

[0091] S102: The material of the robot body is aluminum alloy, and the material of the support table is steel. The density, Young's modulus and Poisson's ratio of these materials are determined as known quantities;

[0092] S103: Select the equivalent concentrated mass of each motion joint of the robot, and the spring stiffness between the robot and the support table as the correction variables, and set their initial values and value ranges.

[0093] The results of steps S102 and S103 are shown in Tables 3 and 4.

[0094] Table 3 Material properties used in the simulation model

[0095] Material Density (kg / mm 3 )]]> Young's modulus (MPa) Poisson's ratio Aluminium alloy 2.75 x 10 -9 ]] 69000 0.33 Steel 7.85 x 10 -9 ]]> 210000 0.3

[0096] Table 4 Initial values and value ranges of equivalent concentrated mass and spring stiffness

[0097]

[0098] S20: Perform modal finite element simulation analysis to obtain the simulation value of the natural frequency, and compare it with the test value of the natural frequency.

[0099] Further, step S20 specifically includes:

[0100] S201: Establish a modal analysis step in the finite element analysis software, and set the analysis step to solve the first q order natural frequency;

[0101] S202: Solve the finite element model to calculate the q order natural frequency simulation value;

[0102] S203: Compare the natural frequency simulation value and the natural frequency test value.

[0103] In this example, q = 8.

[0104] S30: If the relative error between the simulation value and the test value of the natural frequency exceeds the allowable error, adjust the value of the correction variable, and repeat step S20 until the relative error does not exceed the allowable error.

[0105] In this embodiment, the adjustment of the correction variable in step S30 uses a multi-objective genetic optimization algorithm. The objective function is the relative error between the simulation value and the test value, that is, the relative error between the simulation value and the test value of the first q order natural frequency does not exceed the allowable error, which is expressed by the formula:

[0106]

[0107] wherein, is the 1st order natural frequency simulation value, is the 1st order natural frequency test value, is the qth order natural frequency simulation value, is the qth order natural frequency test value, and v represents a set of correction variables.

[0108] The correction results of the equivalent lumped mass and spring stiffness are shown in Table 5. The first 8 order natural frequencies of the model after correction are shown in Table 6, and the corresponding modal shapes are shown in Fig. 6. After correction, the maximum relative error of the natural frequency is 0.92%, the minimum relative error is 0.17%, the average relative error of the first 8 order is 0.56%, all of which are less than the allowable relative error of 1%.

[0109] Table 5 Correction results of equivalent lumped mass and spring stiffness

[0110]

[0111] Table 6 Natural frequencies of the first attitude

[0112]

[0113]

[0114] S40: Update the finite element model using the correction results in S30. That is, modify the equivalent lumped mass and spring stiffness in the finite element model to the correction results in S30.

[0115] S50: Based on the updated model, select unknowns that have a significant influence on the structural vibration response as correction variables, and set the value range and initial value of the correction variables.

[0116] In this embodiment, the structural damping coefficients of the robot, the structural damping coefficients of the support table, and the damping coefficients of the spring-damper model X, Y, and Z in three directions at the connection between the robot and the support table have a significant influence on the structural vibration response, so they are selected as correction variables, and their initial values and value ranges are set as shown in Table 7.

[0117] Table 7 Initial values and value ranges of damping coefficients

[0118]

[0119] S60: Perform harmonic response finite element simulation analysis to obtain the acceleration frequency response function and calculate the average unit impulse response kinetic energy simulation value, and compare it with the average unit impulse response kinetic energy test value.

[0120] Further, step S60 specifically includes:

[0121] S601: Establish a harmonic response analysis step in the finite element analysis software, as shown in Table 8, the analysis step is set to solve the acceleration response function;

[0122] S602: Solve the finite element model to calculate the average unit impulse response kinetic energy simulation value;

[0123] S603: Compare the average unit impulse response kinetic energy simulation value with the average unit impulse response kinetic energy test value.

[0124] Table 8 Analysis step settings for harmonic response simulation

[0125] Analysis step number Analysis step type Load 1 Modal analysis / 2 Harmonic response analysis Excitation point 1 unit force (X direction) 3 Harmonic response analysis Excitation point 2 unit force (Y direction) 4 Harmonic response analysis Excitation point 3 unit force (Z direction)

[0126] S70: If the relative error between the simulation value and the test value of the average unit impulse response kinetic energy exceeds the allowable range, adjust the correction variable value and repeat step S60 until the relative error does not exceed the allowable error.

[0127] In this embodiment, the adjustment of the correction variable in step S70 uses a multi-objective genetic optimization algorithm, and the objective function is the relative error between the simulation value and the test value, that is, the relative error between the simulation value and the test value of the average unit impulse response kinetic energy corresponding to all excitation points does not exceed the allowable error, which is expressed by the formula:

[0128]

[0129] wherein, is the average unit impulse response kinetic energy simulation value corresponding to the first excitation point, is the average unit impulse response kinetic energy test value corresponding to the first excitation point, is the average unit impulse response kinetic energy simulation value corresponding to the mth excitation point, is the average unit impulse response kinetic energy test value corresponding to the mth excitation point, u represents the correction variable set, and m is the number of excitation points. In this embodiment.

[0130] The correction results are shown in Table 9. The average unit impulse response kinetic energy corresponding to the three excitation points after model correction is shown in Table 9. Figure 7 The maximum relative error is 0.36%, the minimum relative error is 0.24%, and the average relative error of the average unit impulse response kinetic energy of the three excitation points is 0.29%, all of which are less than the allowable relative error of 1%.

[0131] Table 9 Damping coefficient correction results

[0132]

[0133] S80: Update the finite element model using the correction results in S70 to complete the model correction.

[0134] (3) Verification of the results of model correction for the second attitude

[0135] Robot's second posture, such as Figure 8 As shown, a finite element model of the robot-support platform structure in the second pose is established. The equivalent lumped mass, spring stiffness of the spring-damper model, structural damping coefficient of the robot, structural damping coefficient of the support platform, and damping coefficients in the X, Y, and Z directions of the spring-damper model at the connection between the robot and the support platform are all derived from the model correction results of the first pose.

[0136] The second posture was tested using a hammer impact test method to obtain the acceleration frequency response function. Then, the natural frequency was obtained through modal analysis, and the results are shown in Table 10. The average unit impulse response kinetic energy was calculated using formula (1) for the average unit impulse response kinetic energy, and the results are shown in Table 11.

[0137] Table 10. Test results of the natural frequencies of the second posture.

[0138]

[0139]

[0140] Table 11 Test Results of Average Unit Impulse Response Kinetic Energy in Second Attitude

[0141] average unit impulse response kinetic test value (m 2 / s 2 )]]> Excitation point one 58.90 Excitation point two 172.80 Excitation point three 58.77

[0142] Following the material properties and analysis steps set in Tables 3 and 8, modal analysis and harmonic response analysis were performed on the second attitude finite element model. The simulation values ​​and test values ​​were compared, and the results are shown in Table 12. Figure 9 As shown, the maximum relative error of the natural frequency is 6.44%, the minimum relative error is 0.18%, and the average relative error of the first 8 orders is 2.90%. The maximum relative error of the average unit impulse response kinetic energy is 4.34%, the minimum relative error is 2.70%, and the average relative error of the average unit impulse response kinetic energy corresponding to the three excitation points is 3.31%. Overall, the errors are small, indicating that the values ​​of the corrected variables obtained from the first attitude model can still reflect the dynamic characteristics of the actual structure well in the second attitude, verifying the effectiveness of the structural dynamics model correction method of the present invention.

[0143] Table 12 Natural frequencies of the second attitude

[0144]

[0145]

[0146] In the present application, the accuracy of the structural dynamics model is improved by correcting part of the unknown quantities with the relative error of the inherent frequency as the target. Then, the remaining unknown quantities are corrected with the relative error of the average unit impulse response kinetic energy as the target, so as to further improve the accuracy of the structural dynamics model. The average unit impulse response kinetic energy is the ratio of the sum of the vibration velocity signal energies of multiple response points in X, Y and Z directions under the action of unit impulse excitation of an excitation point and the number of response points. The structural dynamics model correction method takes the decrease of the relative error of the average unit impulse response kinetic energy corresponding to each excitation point as the target, so the structural dynamics model correction method contains the data of multiple excitation points and multiple response points at the same time, thereby avoiding the deviation problem of the model correction result caused by using only a single excitation point or a single response point, and improving the reliability and accuracy of the correction result.

[0147] The above is a specific description of the preferred embodiment of the present application, but the present application is not limited to the described embodiments. Those skilled in the art can make various equivalent modifications or replacements without departing from the spirit of the present application. These equivalent modifications or replacements are all included in the scope defined by the claims of the present application.

Claims

1. A method for correcting a structural dynamics model, characterized in that, The method includes the following steps; S10: Establish the finite element model of the structure, determine the known quantities, select the unknown quantities that have a significant impact on the natural frequency of the structure as correction variables, and set the range and initial value of the correction variables. S20: Conduct modal finite element simulation analysis to obtain simulated values ​​of natural frequencies and compare them with measured values ​​of natural frequencies; S30: If the relative error between the simulated value and the test value of the natural frequency exceeds the allowable error, adjust the correction variable value and repeat step S20 until the relative error does not exceed the allowable error. S40: Update the finite element model using the correction results from S30; S50: Based on the updated model, select the unknowns that have a significant impact on the structural vibration response as correction variables, and set the range and initial value of the correction variables. S60: Conduct finite element simulation analysis of harmonic response, obtain the acceleration frequency response function, calculate the simulated value of average unit impulse response kinetic energy, and compare it with the measured value of average unit impulse response kinetic energy. The average unit impulse response kinetic energy is the ratio of the sum of the vibration velocity signal energy of multiple response points in the X, Y, and Z directions under the unit impulse excitation at a certain excitation point to the number of response points. Under the excitation at excitation point k, the formula for calculating the average unit impulse response kinetic energy is as follows: Where f represents frequency, h pkx (f) represents the acceleration frequency response function of the response point p in the X direction under the excitation of the excitation point k, h pky (f) represents the acceleration frequency response function of the response point p in the Y direction under the excitation of the excitation point k, h pkz (f) represents the acceleration frequency response function of point p in the Z direction under the excitation of point k, where fl is the lower limit of the frequency. u This is the upper limit of the frequency. S70: If the relative error between the simulated value and the test value of the average unit impulse response kinetic energy exceeds the allowable range, adjust the correction variable value and repeat step S60 until the relative error does not exceed the allowable error. S80: Update the finite element model using the correction results from S70 to complete the model correction.

2. The structural dynamics model correction method according to claim 1, characterized in that, The correction variable selected in step S10 is no longer selected as a correction variable in step S50.

3. The structural dynamics model correction method according to claim 1, characterized in that, The correction variables selected in step S10 include the density, elastic modulus, and constraint stiffness of the component.

4. The structural dynamics model correction method according to claim 1, characterized in that, The correction variables selected in step S50 include the structural loss factor and the damping coefficient.

5. The structural dynamics model correction method according to claim 1, characterized in that, The model correction objective of steps S10-S40 is to ensure that the relative error between the simulated and measured values ​​of the first q natural frequencies does not exceed the allowable error, which can be expressed by the formula: in, This is the simulated value of the first-order natural frequency. This is the measured value of the first-order natural frequency. It is the simulated value of the q-th natural frequency. It is the test value of the q-th natural frequency, and v represents the set of correction variables.

6. The structural dynamics model correction method according to claim 1, characterized in that, The model correction objective of steps S50-S80 is to ensure that the relative error between the simulated and tested average unit impulse response kinetic energy values ​​for all excitation points does not exceed the allowable error, expressed by the formula: in, This is the simulated average unit impulse response kinetic energy value corresponding to the first excitation point. This is the average unit impulse response kinetic energy test value corresponding to the first excitation point. It is the simulated average unit impulse response kinetic energy value corresponding to the m-th excitation point. It is the average unit impulse response kinetic energy test value corresponding to the m-th excitation point, u represents the set of correction variables, and m is the number of excitation points.

7. The structural dynamics model correction method according to claim 1, characterized in that, The specific steps of step S20 include: S201: Establish a modal analysis step in the finite element analysis software, wherein the analysis step is set to calculate the first q natural frequencies; S202: Solve the finite element model and calculate the simulated values ​​of the first q natural frequencies; S203: Compare the simulated value of the natural frequency with the measured value of the natural frequency.

8. The structural dynamics model correction method according to claim 1, characterized in that, The specific steps of step S60 include: S601: Establish a harmonic response analysis step in the finite element analysis software, wherein the analysis step is set to calculate the acceleration response function; S602: Solve the finite element model and calculate the simulated value of the average unit impulse response kinetic energy; S603: Compare the simulated value of average unit impulse response kinetic energy with the measured value of average unit impulse response kinetic energy.

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