Structural dynamics model correction method

Abstract

The invention discloses a structural dynamics model correction method, and belongs to the technical field of model correction. S10, establishing a finite element model of the structure, and setting a correction variable and a value range and an initial value thereof; s20, modal finite element analysis and experimental test value comparison are carried out; s30, if the error between the simulation value and the test value exceeds the allowable range, the step S20 is repeated, and the finite element model is updated; s40, updating the finite element model by utilizing a correction result in the step S30; s50, resetting the correction variable, the range of the correction variable and the initial value of the correction variable; s60, harmonic response finite element analysis and experimental test value comparison are carried out; s70, if the error between the simulation value and the test value exceeds the allowable range, adjusting the correction variable, and repeating the step S60 until the error meets the requirement; and S80, updating the finite element model to complete correction. According to the method, data of a plurality of excitation points and a plurality of response points are included at the same time, the problem of model correction result deviation caused by only using a single excitation point or a single response point at a time is effectively avoided, and the reliability and accuracy of a correction result are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of model correction, and more specifically, to a structural dynamics model correction method. Background Art

[0002] In the design and manufacturing process of industrial equipment, vibration is always a key factor that cannot be ignored. It is directly related to the life of the equipment, operating accuracy and noise control level. With the increasing requirements of modern industry for equipment performance, dynamic analysis and vibration reduction optimization have become the core links of product structure development. As an important means to evaluate the dynamic characteristics of structures and design schemes, the importance of dynamic 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. These differences mainly come from the simplification of assembly connection methods, the idealized setting of constraint stiffness, the approximate treatment of material constitutive relations, etc., which leads to deviations between the results of finite element analysis and the actual situation, thus affecting the effectiveness of design decisions and the optimization of product performance.

[0003] In order to overcome this problem, model correction technology came into being and became a key way to improve the accuracy of finite element analysis. Model correction can not only help identify key parameters that are difficult to measure directly in experiments, such as stiffness, damping, and equivalent concentrated mass distribution, but also effectively compensate for errors introduced by model simplification, thereby improving the reliability of simulation results. The importance of this technology lies in that it makes predictions based on finite element analysis closer to actual observations, reduces the number of design iterations, accelerates product development cycles, and reduces R&D costs.

[0004] The study of model correction methods has always been a hot topic in the field of dynamics and engineering applications. Early studies focused on improving the accuracy of the natural frequency of the model, and explored how to more accurately reflect the dynamic characteristics of the structure through direct or indirect correction methods. For example, studies on composite structures have shown that accurate model correction is crucial to improving the accuracy of finite element models. Qin Xianrong, Wei Sha and other scholars have achieved effective correction of complex systems such as tower cranes and butted cylindrical shell structures through proxy model technologies such as response surface method, and improved the prediction accuracy of natural frequency. With the deepening of research, people realized that it is not enough to focus only on the natural frequency, and the magnitude of the vibration response is equally important. Therefore, a complete model correction should consider both aspects at the same time to ensure that the model can accurately reflect the behavior of the actual structure under a wider range of dynamic conditions. Some studies have achieved accurate correction of the cable-stayed-cable combined model bridge by combining substructures with finite element models and applying experimental design methods, which not only improved the prediction accuracy of the natural frequency, but also optimized the prediction of the vibration response. Some studies have used neural network methods to correct the torsional spring constant of simply supported beams, and predicted static and dynamic responses at the same time, showing the potential for wide application of model correction technology in complex structures.

[0005] Despite many advances, existing model correction 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 correction process complicated and the results unstable. Therefore, exploring a new method that can effectively deal with model correction of highly nonlinear systems has become an urgent need for current research. Summary of the invention

[0006] In order to overcome the shortcomings of the existing technology, a structural dynamics model correction method simultaneously includes data of multiple excitation points and multiple response points, effectively avoiding the problem of model correction result deviation caused by only using a single excitation point or a single response point at a time, and improving the reliability and accuracy of the correction result.

[0007] The technical solution adopted by the invention to solve the technical problem is: a structural dynamics model correction method, the improvement of which is that the method comprises the following steps;

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

[0009] S20: Conduct 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: updating the finite element model using the correction result in S30;

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

[0013] S60: Conduct harmonic response finite element simulation analysis to obtain the acceleration frequency response function, and calculate the average unit pulse response kinetic energy simulation value, and compare it with the average unit pulse 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: updating the finite element model using the correction result in S70, and completing the model correction.

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

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

[0018]

[0019] 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 the response point p in the Z direction under the excitation of the excitation point k, f l is the lower frequency limit, f u is the upper frequency limit.

[0020] Further, the correction variable selected in step S10 is no longer selected as the correction variable in step S50.

[0021] Furthermore, the correction variables selected in step S10 include density, elastic modulus and constraint stiffness of the component.

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

[0023] Furthermore, the model correction target of steps S10-S40 is to make the relative error between the simulation value and the test value of the first q-order natural frequency not exceed the allowable error, which is expressed as:

[0024]

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

[0026] Furthermore, the model correction target of steps S50-S80 is to make the relative error between the average unit impulse response kinetic energy simulation value and the test value corresponding to all excitation points not exceed the allowable error, which is expressed as:

[0027]

[0028] in, 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 set of correction variables, and m is the number of excitation points.

[0029] Furthermore, 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 find the natural frequencies of the first q orders;

[0031] S202: solving the finite element model and calculating the simulation value of the first q-order natural frequency;

[0032] S203: Compare the natural frequency simulation value and the natural frequency test value.

[0033] Furthermore, 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 obtain an acceleration response function;

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

[0036] S603: Compare the average unit impulse response kinetic energy simulation value and the average unit impulse response kinetic energy test value.

[0037] The beneficial effects of the present invention are: data of multiple excitation points and multiple response points are included simultaneously, which effectively avoids the problem of deviation in model correction results caused by using only a single excitation point or a single response point at a time, and improves the reliability and accuracy of the correction results. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A flow chart of a structural dynamics model correction method of the present invention;

[0039] Figure 2 Photo of the assembled collaborative robot-support table structure;

[0040] Figure 3 A flow chart of a verification process of a structural dynamics model correction method of the present invention;

[0041] Figure 4 This is a schematic diagram of the first posture of the assembly collaborative robot;

[0042] Figure 5 To assemble the collaborative robot finite element model;

[0043] Figure 6a The first-order modal vibration shape of the finite element simulation of the assembly collaborative robot-support platform structure;

[0044] Figure 6b The second-order mode vibration shape of the finite element simulation of the assembly collaborative robot-support platform structure;

[0045] Figure 6c The third-order mode vibration shape of the finite element simulation of the assembly collaborative robot-support platform structure;

[0046] Figure 6d The fourth-order mode shape of the finite element simulation of the assembly collaborative robot-support platform structure;

[0047] Figure 6e The fifth-order mode shape of the finite element simulation of the assembly collaborative robot-support platform structure;

[0048] Figure 6f The sixth-order mode shape of the finite element simulation of the assembly collaborative robot-support platform structure;

[0049] Figure 6g The seventh-order mode vibration shape of the finite element simulation of the assembly collaborative robot-support platform structure;

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

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

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

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

[0054] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0055] The following will clearly and completely describe the concept, specific structure and technical effects of the present invention in combination with the embodiments and drawings, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by technicians in this field without creative work are all within the scope of protection of the present invention. In addition, all the connection / connection relationships involved in the patent do not refer to the direct connection of components, but refer to the formation of a better connection structure by adding or reducing connection accessories according to the specific implementation situation. The various technical features in the invention can be combined interchangeably without conflicting with each other.

[0056] It should be noted that if the embodiments of the present invention 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 status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0057] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. Secondly, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

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

[0059] See also Figure 1 As shown, the present invention provides a structural dynamics model correction method, the method comprising the following steps:

[0060] S10: Establish a finite element model of the structure, determine known quantities, select unknown quantities that have a significant impact on the natural frequency of the structure as correction variables, and set the value range and initial value of the correction variables;

[0061] S20: Conduct modal finite element simulation analysis to obtain the natural frequency simulation value and compare it with the natural frequency test value;

[0062] 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;

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

[0064] S50: Based on the updated model, an unknown quantity having a significant impact on the structural vibration response is selected as a correction variable, and a value range and an initial value of the correction variable are set;

[0065] S60: Conduct harmonic response finite element simulation analysis to obtain the acceleration frequency response function, and calculate the average unit pulse response kinetic energy simulation value, and compare it with the average unit pulse response kinetic energy test value;

[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, adjust the correction variable value, and repeat 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, and completing the model correction.

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

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

[0070]

[0071] 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 the response point p in the Z direction under the excitation of the excitation point k, f l is the lower frequency limit, f u is the upper frequency limit.

[0072] In the acceleration frequency response function test, the vibrations in the three directions of X, Y, and Z are tested at each response point. When the excitation is performed at the excitation point, the acceleration frequency response function of each response point in the directions of X, Y, and Z can be obtained. Substituting the above formula, the test value of the average unit impulse response kinetic energy corresponding to the excitation point can be calculated. By performing excitation at other excitation points and substituting the above formula for calculation, the test values ​​of the average unit impulse response kinetic energy corresponding to each of these excitation points can also be obtained.

[0073] Embodiment 1

[0074] The object of this embodiment is to assemble a collaborative robot-support platform structure, such as Figure 2 As shown. The assembly collaborative robot is used in the screw locking process on the assembly production line, hereinafter referred to as the robot. During the locking process, the robot generates large vibrations. In order to analyze and evaluate the impact of vibration on the reliability of the robot, it is necessary to establish an accurate finite element model of the robot structure. There are many parameters in the structure that are difficult to measure directly. Therefore, the structural dynamics model correction method of the present invention is used to achieve model correction, as follows.

[0075] The robot is equipped with six motion joints, each of which contains components such as a harmonic reducer, a drive motor, and a circuit board, which have a large mass and have a significant impact on the robot's dynamic behavior. 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 invention.

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

[0077] In addition, the structural damping coefficients of the robot and the support platform have 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 invention.

[0078] like Figure 3As shown, two postures of the robot model are selected in this embodiment. The first posture is used for model correction to determine the three unknown quantities of equivalent concentrated mass, spring stiffness and structural damping coefficient. The second posture is used to verify the results of model correction. First, a finite element model of the first posture is established, and the unknown quantities of the model are corrected using the natural frequency test values ​​and average unit pulse response kinetic energy test values ​​obtained in the first posture; then, a finite element model of the second posture is established, and the three unknown quantities of equivalent concentrated mass, spring stiffness and structural damping coefficient directly use the correction results of the first posture; finally, the natural frequency and average unit pulse response kinetic energy of the second posture are simulated and calculated. If their simulation values ​​are close enough to the test values, the correction results are considered to be correct, thereby verifying the effectiveness of the structural dynamics model correction method of the present invention.

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

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

[0081] In the hammer test, an excitation point is selected in each of the three directions X, Y, and Z, so m = 3, such as Figure 4 As shown. Five response points are selected along the robot, so n = 5. A three-axis acceleration sensor is arranged at each response point, and there are 15 acceleration test signal channels in total.

[0082] Each excitation point is hammered in turn, and the force signal and 15 acceleration signals of the hammer are collected at the same time to obtain the acceleration frequency response function. Then the natural frequency is obtained through modal analysis, and the results are shown in Table 1. The average unit impulse response kinetic energy is calculated by the calculation formula of the average unit impulse response kinetic energy, and the results are shown in Table 2.

[0083] Table 1 Natural frequency test results of the first posture

[0084] Modal Order Test value of the first posture 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 First posture average unit impulse response kinetic energy test results

[0086] <![CDATA[Average unit impulse response kinetic energy test value of the first posture (m 2 / s 2 )]]> Motivation point 1 60.70 Motivation point 2 169.42 Motivational point three 49.83

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

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

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

[0090] S101: Establishing a finite element model of the robot-support platform structure according to the first posture thereof;

[0091] S102: The material of the robot body is aluminum alloy, and the material of the support platform 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 platform as 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 <![CDATA[Density (kg / mm 3 )]]> Young's modulus (MPa) Poisson's ratio Aluminum Alloy <![CDATA[2.75×10 -9 ]]> 69000 0.33 steel <![CDATA[7.85×10 -9 ]]> 210000 0.3

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

[0097]

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

[0099] Furthermore, step S20 specifically includes:

[0100] S201: establishing a modal analysis step in the finite element analysis software, wherein the analysis step is set to find the natural frequencies of the first q orders;

[0101] S202: solving the finite element model and calculating 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 correction variable value 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 adopts 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 first q-order natural frequency does not exceed the allowable error, which is expressed as follows:

[0106]

[0107] in, is the first-order natural frequency simulation value, is the first-order natural frequency test value, is the qth order natural frequency simulation value, is the qth order natural frequency test value, and v represents the set of correction variables.

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

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

[0110]

[0111] Table 6 Natural frequency of the first posture

[0112]

[0113]

[0114] S40: updating the finite element model using the correction result in S30, that is, modifying the equivalent concentrated mass and spring stiffness in the finite element model to the correction result in S30.

[0115] S50: Based on the updated model, an unknown quantity that has a significant impact on the structural vibration response is selected as a correction variable, and a value range and an initial value of the correction variable are set.

[0116] In this embodiment, the structural damping coefficient of the robot, the structural damping coefficient of the support platform, and the damping coefficients of the spring-damper model at the connection between the robot and the support platform in the X, Y, and Z directions have a significant effect 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 value and range of damping coefficient

[0118]

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

[0120] Furthermore, step S60 specifically includes:

[0121] S601: Establishing a harmonic response analysis step in the finite element analysis software, as shown in Table 8, wherein the analysis step is set to obtain an 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 and 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 1 unit force at the excitation point (X direction) 3 Harmonic response analysis Unit force at excitation point 2 (Y direction) 4 Harmonic response analysis 3 unit force at the excitation point (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 adopts 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 average unit impulse response kinetic energy simulation value and the test value corresponding to all excitation points does not exceed the allowable error, which is expressed as follows:

[0128]

[0129] in, 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 the model correction is as follows: Figure 7 As shown, the maximum relative error is 0.36%, the minimum relative error is 0.24%, and the average relative error of the average unit pulse 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: updating the finite element model using the correction result in S70, and completing the model correction.

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

[0135] The robot's second posture is Figure 8 As shown in Figure 1, a finite element model of the second posture of the robot-support platform structure is established. The equivalent concentrated mass of this model, the spring stiffness of the spring-damper model, the structural damping coefficient of the robot, the structural damping coefficient of the support platform, and the damping coefficients of the spring-damper model in the X, Y, and Z directions at the connection between the robot and the support platform are all derived from the model correction results of the first posture.

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

[0137] Table 10 Natural frequency test results of the second posture

[0138]

[0139]

[0140] Table 11 Second posture average unit impulse response kinetic energy test results

[0141] <![CDATA[Average unit impulse response kinetic energy test value (m 2 / s 2 )]]> Motivation point 1 58.90 Motivation point 2 172.80 Motivational point three 58.77

[0142] According to the material properties and analysis step settings in Table 3 and Table 8, the modal analysis and harmonic response analysis of the second posture finite element model are carried out, and their simulation values ​​and test values ​​are compared. The results are shown in Table 12, Fig. 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 pulse response kinetic energy is 4.34%, the minimum relative error is 2.70%, and the average relative error of the average unit pulse response kinetic energy corresponding to the three excitation points is 3.31%. Overall, the error is small, indicating that the correction variable value obtained from the first posture model correction can still better reflect the dynamic characteristics of the actual structure in the second posture, verifying the effectiveness of the structural dynamics model correction method of the present invention.

[0143] Table 12 Natural frequency of the second posture

[0144]

[0145]

[0146] In the present invention, the accuracy of the structural dynamics model is improved by correcting a part of the unknowns with the goal of reducing the relative error of the natural frequency. Then, the updated finite element model is used to correct the remaining unknowns with the goal of reducing the relative error of the average unit pulse response kinetic energy, thereby further improving the accuracy of the structural dynamics model. The average unit pulse response kinetic energy is the ratio of the sum of the energy of the vibration velocity signals of multiple response points in the three directions of X, Y, and Z under the unit pulse excitation of a certain excitation point to the number of response points. The structural dynamics model correction method aims to reduce the relative error of the average unit pulse response kinetic energy corresponding to each of the multiple excitation points. Therefore, the structural dynamics model correction method simultaneously includes data of multiple excitation points and multiple response points, thereby avoiding the model correction result deviation problem that may be 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 implementation of the present invention, but the invention is not limited to the embodiments. Those skilled in the art can make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A structural dynamics model correction method, characterized in that: The method comprises the following steps: S10: Establish a finite element model of the structure, determine known quantities, select unknown quantities that have a significant impact on the natural frequency of the structure as correction variables, and set the value range and initial value of the correction variables; S20: Conduct modal finite element simulation analysis to obtain the natural frequency simulation value and compare it with the natural frequency test value; 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; S40: updating the finite element model using the correction result in S30; S50: Based on the updated model, an unknown quantity having a significant impact on the structural vibration response is selected as a correction variable, and a value range and an initial value of the correction variable are set; S60: Conduct harmonic response finite element simulation analysis to obtain the acceleration frequency response function, and calculate the average unit pulse response kinetic energy simulation value, and compare it with the average unit pulse response kinetic energy test value; 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; S80: updating the finite element model using the correction result in S70, and completing the model correction.

2. A structural dynamics model correction method according to claim 1, characterized in that: The average unit pulse response kinetic energy is the ratio of the sum of the vibration velocity signal energies of multiple response points in the X, Y, and Z directions under the unit pulse excitation of a certain excitation point to the number of response points.

3. A structural dynamics model correction method according to claim 2, characterized in that: Under the excitation of the excitation point k, the corresponding average unit impulse response kinetic energy calculation formula is: Where f represents frequency, k 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 the response point p in the Z direction under the excitation of the excitation point k, f l is the lower frequency limit, f u is the upper frequency limit.

4. A 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 .

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

6. A 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.

7. A structural dynamics model correction method according to claim 1, characterized in that: The model correction target of the steps S10-S40 is to make the relative error between the simulation value and the test value of the first q-order natural frequency not exceed the allowable error, which is expressed as: in, is the first-order natural frequency simulation value, is the first-order natural frequency test value, is the qth order natural frequency simulation value, is the qth order natural frequency test value, and v represents the set of correction variables.

8. A structural dynamics model correction method according to claim 1, characterized in that: The model correction target of steps S50-S80 is to make the relative error between the average unit impulse response kinetic energy simulation value and the test value corresponding to all excitation points not exceed the allowable error, which is expressed as: in, 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 set of correction variables, and m is the number of excitation points.

9. A structural dynamics model correction method according to claim 1, characterized in that: The specific steps of step S20 include: S201: establishing a modal analysis step in the finite element analysis software, wherein the analysis step is set to find the natural frequencies of the first q orders; S202: solving the finite element model and calculating the simulation value of the first q-order natural frequency; S203: Compare the natural frequency simulation value and the natural frequency test value.

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

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