CN-122020877-A - Mechanical system dynamics modeling method

CN122020877ACN 122020877 ACN122020877 ACN 122020877ACN-122020877-A

Abstract

The invention discloses a mechanical system dynamics modeling method, which relates to the technical field of mechanical dynamics, and comprises the steps of decomposing a target mechanical system into a plurality of sets of structural components; the method comprises the steps of carrying out finite element modeling on each structural component to obtain a finite element model of each structural component, carrying out dynamics reduction processing on the finite element model to obtain a polycondensation model of each structural component, integrating and coupling the polycondensation model into a system body dynamics model based on the motion parameters of each motion axis of a target mechanical system and the system assembly relation, and coupling the dynamics model of an end effector with the system body dynamics model to obtain the target system dynamics model. The real dynamic behavior of the mechanical system in different working spaces is accurately reflected by decomposing the whole machine into components and respectively performing reduced-order processing and then dynamically integrating according to real-time motion parameters, so that the limitation of traditional static modeling is overcome.

Inventors

YANG YIQING
LI LONGPENG
ZHANG RUNDONG

Assignees

北京航空航天大学

Dates

Publication Date: 20260512
Application Date: 20251230

Claims (10)

1. A method of modeling mechanical system dynamics, the method comprising: decomposing a target mechanical system into a collection of structural components and using an end effector of the target mechanical system as a couplable module independent of a system body; carrying out finite element modeling on each structural component to obtain a finite element model of each structural component; performing dynamic reduced-order processing on the finite element model to obtain a polycondensation model of each structural component; according to the relation between the motion parameters of each motion axis of the target mechanical system and system assembly, the polycondensation model is integrated and coupled into a system body dynamics model; And coupling the dynamics model of the end effector with the system ontology dynamics model to obtain a target system dynamics model.
2. The method of claim 1, wherein integrally coupling the polycondensation model to a system ontology dynamics model based on the motion parameters of each motion axis of the target mechanical system and the system assembly relationship comprises: Establishing a global coordinate system and a local coordinate system, and calculating a pose transformation matrix of each structural component according to the motion parameters and the system assembly relation; The polycondensation model of each structural component is uniformly converted into a global coordinate system by utilizing the pose transformation matrix, wherein the structural components which belong to the same functional component and do not have relative motion are integrated by adopting a rigid coupling method to obtain a first matrix of the system; and assembling the first system matrix and the second system matrix to obtain the system ontology dynamic model, wherein the system ontology dynamic model is updated in real time along with the motion parameters.
3. The method of claim 2, wherein the integration of structural components belonging to the same functional component and having no relative motion using a rigid coupling method results in a first matrix of the system, comprising: respectively defining the joint surfaces of two to-be-coupled structural components as a master interface and a slave interface; Triangular mesh division is carried out on the node set of the main interface, and a shape function is constructed to establish a continuous displacement field; mapping the nodes of the slave interfaces to grid cells corresponding to the master interfaces, and establishing a constraint equation based on rigid connection assumption; and according to the constraint equation, eliminating redundant degrees of freedom through matrix operation, and assembling to obtain a coupled system first matrix.
4. The method of claim 2, wherein the integration of the structural components with different functions of relative motion using a flexible coupling method results in a second matrix of the system, comprising: respectively defining the joint surfaces of two functional components to be coupled as a master interface and a slave interface; Performing grid division on the node set of the main interface to construct an interpolation function; defining equivalent stiffness coefficients and damping coefficients of the joint surface in three directions X, Y, Z so as to be distributed to the nodes of the slave interface; And mapping the equivalent stiffness coefficient and the damping coefficient to a node corresponding to the main interface by utilizing the interpolation function, and assembling to obtain a coupled system second matrix by modifying the system matrix integration flexible connection characteristic.
5. The method of claim 1, wherein subjecting the finite element model to a dynamic reduction process results in a polycondensation model for each structural component, comprising: Classifying model degrees of freedom corresponding to all finite element models, and screening out a target degree of freedom set, wherein the target degree of freedom is target modal information of the coverage structure and comprises node degrees of freedom at a connecting interface; constructing a coordinate transformation matrix according to the target degree of freedom set so as to project the finite element model to a low-dimensional space formed by the target degrees of freedom; And generating a polycondensation model conforming to a preset degree of freedom through matrix operation according to the coordinate transformation matrix and the finite element model.
6. The method of claim 1, wherein coupling the kinetic model of the end effector with the system ontology kinetic model results in a target system kinetic model, comprising: according to the structural characteristics of the end effector, establishing a preliminary dynamics model of a dynamics matrix representing dynamic characteristics; Establishing a connection interface model of the end effector and the system body based on interface attributes of the preliminary dynamics model of the end effector, and determining mechanical parameters based on the connection interface model; and integrating the initial dynamics model of the end effector with the system body dynamics model by adopting a rigid coupling and/or flexible coupling method according to the connection interface model and the mechanical parameters to obtain a target system dynamics model.
7. The method of claim 1, wherein finite element modeling each of the structural components to obtain a finite element model of each structural component comprises: For each structural component, carrying out finite element mesh division on the structural component to generate a discretization model formed by nodes and units; Based on the discretization model, the finite element model is generated by combining the physical properties of the materials of the structural component, and the finite element model comprises a mass matrix, a rigidity matrix and a damping matrix corresponding to the structural component.
8. The method of claim 1, wherein decomposing the target mechanical system into a set of a plurality of structural components comprises: The system main body is divided into a plurality of independent basic structure units according to the functional distribution and the kinematic characteristics of the target mechanical system, the basic structure units comprise a core bearing component, a motion transmission component and an auxiliary supporting component, if the basic structure units are formed by a plurality of detachable connection modules, the basic structure units are detached according to the physical boundaries of the modules to form a plurality of geometrical structure components capable of independently carrying out dynamics characterization, and if the basic structure units are not formed by a plurality of detachable connection modules, the basic structure units are a structural component.
9. The method as recited in claim 1, further comprising: Applying excitation to the target mechanical system, collecting dynamic response signals, calculating a frequency response function based on the excitation and response signals, and extracting experimental modal parameters, wherein the experimental modal parameters comprise inherent frequencies, modal damping ratios and modal vibration modes of all orders; Based on the experimental modal parameters, driving the target system dynamics model to calculate theoretical modal parameters; calculating a difference between the theoretical modal parameter and the experimental modal parameter; Correcting a joint surface parameter in the target system dynamics model by taking the minimized difference value as a target, wherein the joint surface parameter comprises an equivalent stiffness coefficient and a damping coefficient; Calculating a simulation frequency response function under experimental excitation conditions by using the corrected target system dynamics model; and if the coincidence degree of the simulated frequency response function and the frequency response function on the frequency, the amplitude and the phase of the target formant does not meet the preset tolerance, continuing to carry out iterative correction until the preset tolerance is met.
10. A mechanical system dynamics modeling system, the system comprising: A decomposition module for decomposing a target mechanical system into a set of a plurality of structural components and taking an end effector of the target mechanical system as a couplable module independent of a system body; the finite element modeling module is used for carrying out finite element modeling on each structural component to obtain a finite element model of each structural component; the order reduction module is used for carrying out dynamic order reduction processing on the finite element model to obtain a polycondensation model of each structural component; The first coupling module is used for integrally coupling the polycondensation model into a system body dynamics model according to the motion parameters of each motion axis of the target mechanical system and the system assembly relation; and the second coupling module is used for coupling the dynamics model of the end effector with the system body dynamics model to obtain a target system dynamics model.

Description

Mechanical system dynamics modeling method Technical Field The invention relates to the technical field of mechanical dynamics, in particular to a mechanical system dynamics modeling method. Background With the continuous development of modern manufacturing industry to high precision and high efficiency, the dynamic performance of a numerical control machine tool has become a core for determining the processing quality, efficiency and even reliability of the numerical control machine tool. Especially in high-end application scenes such as high-speed cutting, five-axis linkage processing and the like, the problems of flutter, deformation and vibration caused by the dynamic characteristics of a machine tool structure are particularly remarkable. Therefore, the dynamic model capable of accurately predicting the dynamic response of the machine tool under the actual working condition is constructed, and the dynamic model has important significance for realizing virtual simulation, optimizing cutting parameters, inhibiting machining chatter and performing performance-driven machine tool design. At present, the mainstream modeling method in the field mainly comprises three types, namely a finite element analysis method, an experimental modal analysis method, a comprehensive analysis method and a comprehensive analysis method, wherein the finite element analysis method can guarantee the accuracy of a model through a high-density grid discrete complex structure, but the calculation cost is high, the experimental modal analysis method is based on actual measurement data of a physical model machine, the result is direct and reliable, but the experimental modal analysis method cannot be applied to prediction optimization in a design stage, the comprehensive analysis method is used for trying to integrate the advantages of the two, a parameterized model is constructed by utilizing finite elements, and calibration and correction are carried out through experimental data, so that the prediction capability and the practicability of the model are improved. Despite the remarkable progress made by the existing research methods, the existing research methods still have a plurality of defects, and the engineering application value of the existing research methods is severely limited. First, models lack the ability to reconstruct in real time that existing models are mostly static, built only for machine tool specific configurations (e.g., axes in some fixed position). However, the numerical control machine is a typical moving structure, and its mass distribution and rigidity distribution are changed in real time with the movement of each feed shaft. The current method can not realize the dynamic association of the model parameters and the machine tool motion parameters, and can not reflect the dynamic characteristic change of the machine tool at different working space positions. In addition, the mechanical characteristic treatment of the joint surface is too simplified, and particularly in a comprehensive analysis method, the conventional structural component coupling method is too ideal for the mechanical behavior treatment of key joint surfaces such as a guide rail sliding block, a main shaft bearing, bolt connection and the like, so that the problems of local rigidity hardening and the like are easily caused, and the model prediction precision is insufficient. Finally, the contradiction exists between modeling efficiency and application requirements, the finite element method is low in calculation efficiency and difficult to meet real-time simulation requirements, and the experimental rule is seriously dependent on a physical model machine and cannot support early-stage design optimization. Disclosure of Invention The invention mainly aims to provide a mechanical system dynamics modeling method. The method solves the problems that the traditional finite element method has low calculation efficiency caused by huge degree of freedom of a model, and a static model can not reflect dynamic characteristic change of the system under different motion postures. The whole machine is decomposed into components and subjected to order reduction processing respectively, and then dynamic integration is carried out according to real-time motion parameters, so that the calculation efficiency is improved on the premise of ensuring the accuracy, the real dynamic behaviors of the mechanical system in different working spaces are accurately reflected, and the limitation of traditional static modeling is overcome. In order to achieve the above object, the embodiment of the present application provides the following technical solutions: According to a first aspect of an embodiment of the present application, there is provided a mechanical system dynamics modeling method, the method comprising: decomposing a target mechanical system into a collection of structural components and using an end effector of the target mechanical system as a couplable