带伸展柔性附件航天器系统动力响应的精细积分算法

带伸展柔性附件航天器的动力学方程是刚 -柔耦合的时变非线性动力学方程 ,用传统方法求解其动力学响应时会遇到很大的困难。精细积分法在求解刚性方程和常系数线性方程时显示出很大的优越性 ,这为柔性体系动力学方程的求解提供了新的工具。本文将精细积分法加以改进 ,并将之应用于刚 -柔耦合系统动力学方程 ,采用带伸展柔性附件航天器系统动力学模型 ,研究结构的动态特征变化规律 ,得出了一些有意义的结论     

Numerical and experimental investigation on electromechanical aileron actuation system with joint clearance

A closed-loop coupling model at the system-level is developed to analyze the effects of joint clearance on the dynamic responses of electromechanical aileron actuation system. The proposed model considers the coupling effects between the electromechanical actuator (EMA) control performance and dynamic characteristics of linkage mechanism with joint clearance. Besides, the experiments are conducted in a test rig, which verifies the effectiveness of the proposed closed-loop coupling model. The nonlinear contact force model and modified Coulomb friction model are adopted in the joint clearance of the linkage mechanism, and the influences of clearance size on the dynamic behaviors of electromechanical aileron actuation system are studied. The numerical and experimental results indicate that the novel closed-loop coupling model, considering the EMA control performance and dynamics of linkage mechanism with joint clearance at the same time, is an effective model to predict the dynamic characteristics of electromechanical aileron actuation with joint clearance, which provides a practical method to analyze the dynamic performance of electromechanical coupling multibody systems with joint clearance.

     

柔性多体系统动力学的递推建模与算法

基于将２种变量的耦合运算降低到最少的数学模型的建立,是解决柔性多体系统动力学数值病态的关键。提出一种柔性多体系动力学的单向递推建模方法。在此基础上提出了一种新的违约校正方法,在数值计算上给予保证,最后,通过对一个闭环柔性多体系统的动力学与控制仿真计算的实现,表明上述方法的可行性。     

混联虚拟轴研抛机床的多柔体动力学研究

为了在自由曲面的弹性研抛中 ,获得稳定的动力学特性和加工效果 ,开发了一种由“3轴并联 + 2轴串联”构成的新型 5自由度混联虚拟轴研抛机床。采用柔性多体系统动力学方法 ,建立了基于Lagrange方程的空间刚 柔耦合动力学模型 ;考虑研抛机床整体的刚性运动与各支链弹性变形间的相互作用及耦合 ,将机床的各个支链和平台看作独立子结构 ,建立各自的动力学方程 ,根据子结构之间的约束关系建立了系统约束动力学方程 ;通过动力学仿真分析 ,获得了较稳定的动力学特性     

基于键合图的多体系统耦合动力学的发展及现状

介绍了键合图理论及应用研究的概况,阐述了键合图理论在多能域耦合系统全局动力学的研究中所占有的重要地位。详细地阐述了基于键合图理论的多体系统耦合动力学的发展及现状,包括多体系统键合图模型的建立方法、多体系统键合图模型中微分因果环的解耦策略、系统状态方程及运动副约束反力方程的计算机辅助建立方法等重要问题。     

回转键合图法进行空间多体动力系统建模与仿真

为提高多能域耦合空间多体动力系统建模与仿真的效率及可靠性,提出了回转键合图法。阐述了建立空间多体系统键合图模型的一般方法及其动力学原理。基于回转键合图推导出便于计算机自动生成的系统状态方程及运动副约束反力方程的统一公式,克服了微分因果关系及非线性结型结构给系统自动建模与仿真所带来的代数困难。所述方法特别适合于多能域并存的系统,通过实例说明本文方法的有效性。     

Electromechanical coupling modeling simulation and experimental study of crawler

The electromechanical coupling performance of crawler machinery is investigated. A dynamic equation of electromechanical coupling of crawler machinery is established under multi-typical working conditions. The variation in performance of electromechanical parameters during unstable operations over time is analyzed using the virtual prototype and electromechanical coupling model of crawler machinery. The correctness of the electromechanical coupling model is confirmed by comparing the theoretical analysis, virtual prototype simulation, and physical prototype results. This study provides accurate and valuable theoretical methods and fundamental knowledge to analyze the electromechanical and road driving performance as well as to develop and design a crawler machinery.

     

柔性多体动力学在工程机械设计中的应用研究

将刚柔耦合多体机械系统动力学建模方法应用于工程机械的动力学建模，获得了一组依赖于广义坐标的微分／代数方程组，此即为多体机械系统动力学模型。求解该方程组，可获得机械系统的运动学参量；再引入有限单元网格划分，通过形函数可建立系统运动学参量与系统结构应变之间的关系；该应变关系可用来计算系统结构的动应力和疲劳寿命。文中给出了实现以上思想的基本程序框图，编制了程序ＤＡＭＳＩ，并以门座式起重机为实例，说明了本文提出的方法的可行性。     

基于刚柔耦合的自动化动力学仿真分析研究

刚柔耦合是多体系统最常见的力学模型,在其建模分析过程中存在一定的复杂性与重复性。以三连杆机构为例,通过ANSYS和ADAMS实现刚柔耦合全分析过程,并利用ModelCenter的QuickWrap技术对整个分析过程的功能点进行组件封装,最后通过封装好的组件搭建刚柔耦合分析流程,最终实现自动化的刚柔耦合分析,为进一步的DOE及优化分析奠定了基础。     

计及变形耦合的双连杆柔性机械臂动力学模型

根据连续介质的几何非线性变形原理,结合柔性多体系统建模理论的最新进展,在柔性梁的纵向、横向变形位移中均考虑了横向弯曲变形以及轴向伸缩变形的耦合作用,对一双连杆柔性机械臂系统,将其简化为柔性梁结构,利用有限元法和Lagrange方程,得出不同于传统零次近似方程,也不同于一次耦合动力学方程的新方程, 并可将此方程拓展到多杆机械臂系统。模型包含了二次耦合附加项,并且由于增加了变形耦合量,对柔性梁产生了“软化”作用,使得柔性机械臂模型不同于传统动力学模型。最后,计算仿真说明了这种差异,揭示了新模型的特点和有效性。     

作大范围运动柔性梁的一种碰撞动力学求解方法

研究作大范围运动柔性梁的碰撞动力学问题。针对梁碰撞前、碰撞过程、碰撞后三个阶段,分别建立各阶段的动力学方程。基于柔性多体系统刚柔耦合动力学理论,建立梁无碰撞时的刚柔耦合动力学方程。结合冲量动量法和接触约束法提出一种碰撞动力学求解方法,先以冲量动量法实现运动转换得到协调的碰撞初始条件,再以接触约束法求解碰撞过程。导出系统的刚柔耦合碰撞动力学方程,给出了接触、分离判据,实现三个不同阶段的转换与动力学求解。编制仿真软件,对实例进行动力学仿真,得到系统不同阶段的动力学响应。研究表明,所提碰撞求解方法可以较方便地用于计算柔性多体系统的碰撞问题。梁的柔性、大范围运动及碰撞效应相互耦合,碰撞行为对于柔性多体系统碰撞过程和碰撞后的全局动力学性态均产生较大的影响。     

考虑刚柔耦合效应的塔机水平臂回转制动分析

着重讨论塔式起重机吊臂回转制动过程中运动弹性动力分析问题,在回转运动分析中考虑了机构大位移造成的刚体运动与结构自身弹性变形之耦合,运用柔性多体系统动力学理论在回转平面内建立了吊臂的动力学模型,给出分析与求解方法,并对某实际塔机进行了运动弹性动力分析,得出与塔机实际动力特征相符的结果.     

Study on the dynamic model and simulation of a flexible mechanical arm considering its random parameters

Randomness exists in engineering Tolerance, assemble-error, environment temperature and wear make the parameters of a mechanical system uncertain So the behavior or response of the mechanical system is uncertain In this paper, the uncertain parameters are treated as random variables So if the probability distribution of a random parameter is known, the simulation of mechanical multibody dynamics can be made by Monte-Carlo method Thus multibody dynamics simulation results can be obtained in statistics A new concept called functional reliability is put forward in this paper, which can be defined as the probability of the dynamic parameters (such as position, orientation, velocity, acceleration etc) of the key parts of a mechanical multibody system belong to their tolerance values A flexible mechanical arm with random parameters is studied in this paper The length, width, thickness and density of the flexible arm are treated as random variables and Gaussian distribution is used with given mean and variance Computer code is developed based on the dynamic model and Monte-Carlo method to simulate the dynamic behavior of the flexible arm At the same time the end effector’s locating reliability is calculated with cncular tolerance area The theory and method presented in this paper are applicable on the dynamics modeling of general multibody systems     

部件柔性对含间隙多体系统动力特性的影响

构建了含有混合间隙的刚柔耦合多体系统动力学模型,研究了部件柔性对多体系统动力特性的影响。首先,建立了混合间隙碰撞力模型;然后,以曲柄滑块为研究对象,采用自然坐标法和绝对节点坐标法分别建立了刚性构件和柔性构件的动力学模型,通过时域和频域分析了连杆柔性对动力特性的影响。结果表明,柔性构件对间隙碰撞力有一定的缓冲作用,能缓冲碰撞的高频振动,而且柔性部件随着弹性模量的减小对高频响应的缓冲效果更加明显。     

DYNAMIC MODELLING OF BAR-GEAR MIXED MULTIBODY SYSTEMS USING A SPECIFIC FINITE ELEMENT METHOD

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A straight methodology to include multibody dynamics in graduate and undergraduate subjects

Multibody dynamics discipline is so mature and has so many applications in the industry, that currently it is essential for mechanical engineering students to learn its basic theoretical foundations. However, universities cannot always integrate the matter as a standalone subject. This article presents an efficient methodology to teach kinematic and dynamic analysis of 3D multibody systems in courses with severe time constraints. A simple theoretical approach (the natural or fully Cartesian coordinates) and a high level programming language (MATLAB) are used. The theory level is shown with two examples: a closed-chain 3D robot and a McPherson car suspension system. Several real exam exercises at the end illustrate the skills acquired by the students in courses of 12 h of theory and 15 h of personal work. This methodology overcomes the limitation of time and the complexity of the issue, and turns out to be one of the simplest approaches to teach multibody systems theory in short graduate or undergraduate courses.     

Kinematics analysis and numerical simulation of a manipulator based on virtual prototyping

Manipulator kinematics refers the analytical study of the motion of manipulator, such as positions, velocities, and accelerations of the links of a manipulator. As formulating the suitable kinematics models for a manipulator is very crucial for analyzing the behavior of manipulators and light weight design of manipulators, many researches have been focused on it in recent decades with a result of many valuable contributions. However, current researches always focus on rigid manipulator, while the manipulator is always a rigid-flexible coupling multibody system, which can affect the accuracy of kinematics analysis and numerical simulation. This paper proposed a model of kinematics analysis of manipulator based on rigid-flexible coupling virtual prototyping. After a model of manipulator kinematics based on the D-H method was proposed, rigid-flexible coupling virtual prototyping-based kinematics simulation and numerical simulation was then put forward. The kinematical experiment is carried out based on manipulator physical prototyping, which demonstrates that the accuracy of the kinematics calculation and the rationality of design based on rigid-flexible coupling virtual prototyping. The design of a five-degrees-of-freedom manipulator is given as an example, which demonstrates that the methodology is obviously helpful to manipulator design.     

Prediction of the transient energy response for complex vibro-acoustic systems

As research works of the transient statistical energy analysis (TSEA) and transient local energy approach (TLEA) mostly focus on simple structures, TSEA and TLEA are adopted to quantify the transient response of a complex vibro-acoustic system at the mid-high frequency range in this paper. Numerical examples of a coupled oscillator system, an L-shaped plate, and a launch vehicle fairing model are conducted to demonstrate the effectiveness and accuracy of TSEA and TLEA. The computational precision of TSEA and TLEA is verified by the analytical solution and finite element method. Furtherly, the transient energy responses of subsystems with different coupling ratios between subsystems are investigated. Results show that TLEA has a better performance than TSEA. With the increasing coupling ratio between subsystems, the rise time and peak energy of transient energy response of subsystems decrease gradually. Both ratios of rise time and peak energy predicted by TLEA to these of the TSEA increase as the rising of the coupling ratio.

     

空间结构之间对太阳直接辐射的遮挡算法的研究

通过研究空间结构之间对太阳直接辐射的遮挡，提出了一种快速可行的遮挡算法。运用该算珐，对杆件与杆件的遮挡以及杆件与曲面片之间的遮挡进行计算机仿真，结果和实际光照模型基本一致。结果表明该遮挡算珐是一种行之有效的多体遮挡算珐，为空间结构精确的热计算和热分析奠定了基础。