基于MATLAB的四杆机构运动分析与动画模拟系统

介绍利用MATLAB开发机构运动分析和动画模拟系统的方法，并给出了四杆机构运动分析和动画模拟系统设计实例。     

双四杆机构的运动分析及其优化

双四杆机构因其数学模型复杂,其速度和加速度曲线一直是研究的难点。以啤酒装箱机为例,探讨了啤酒装箱机双四杆机构的运动分析及其优化问题。将数学建模的专用软件Mathematica引入到啤酒装箱机双四杆机构的运动分析中,得到了速度与加速度特性曲线,并在此基础上进一步对双四杆机构进行优化。最后用参数化T-FLEX CAD软件对优化结果的运动轨迹进行仿真验证,获得了令人满意的效果。     

Dynamics of rotor rub in annular clearance with experimental evaluation

Rubbing phenomena in rotor dynamics are investigated by theoretical and experimental approaches. Generating conditions of forward whirling, backward rolling, backward slipping, and partial rubbing are established for system parameters and rotor speeds. Possible whirling motions of the rotor in annular clearance are calculated for full annular rub under the conditions of positive normal force and geometric constraints. The theoretical calculations show that greater clearance results in greater runout and normal force, and the whirling responses are characterized by which natural frequency of the rotor or the stator is greater than the other. Receptances of the rotor and stator are used to explain the possibility of slipping for backward slipping and forward whirling, respectively. Effect of rotor eccentricity is also considered to find the maximum rotor speed for backward slipping during increasing rotor speed and the occurrence of forward whirl. Experiments are performed for two cases. The experimental results show good agreements with the theoretical predictions.     

Dynamic modeling and analysis of a four-bar mechanism coupled with a CVT for obtaining variable input speeds

This paper proposes a novel concept to obtain variable input speeds for a four-bar mechanism driven by an A.C. motor. In such a system, a continuously variable transmission (CVT) is proposed to use instead of an inverter-controlled motor. By this way, the speed variability which is crucial for obtaining different manufacturing and transportation processes can be provided by mechanically. Thus, more efficient system can be achieved than classical motor controlled systems since the CVT allows electrical motor to run at its nominal point in all conditions. For analyzing the dynamics of this new system, a theoretical model is established regarding that a half toroidal CVT is added between the motor and the mechanism. The simulation results associated with the systems with and without a CVT are presented by comparing to each other. The results indicate that the four-bar mechanism equipped with a CVT is feasible for the entire range of possible reduction ratios of the CVT.     

基于ADAMS的锁紧臂机构的动力学仿真及参数化分析

在一自动对接机构设计中,为了获得符合应用要求的锁紧臂机构参数,采用系统动力学仿真软件ADAMS建立了锁紧臂机构的动力学仿真模型,利用ADAMS软件的分析工具对参数化锁紧臂机构模型进行分析研究,获得了符合应用要求的参数值,从而实现了锁紧臂机构的优化设计.     

VB在平面四连杆机构运动分析中的应用

介绍了基于VB实现对平面四连杆机构进行全面运动分析的方法.通过一种简单有效的方法建立了数学模型,采用计算机模拟技术,能动态演示机构的运动和自动绘制连杆上任意点的轨迹曲线,并能输出各运动构件的位移图、速度图和加速度图.为平面四连杆的运动分析提供了一条简单易行的途径.     

含间隙曲柄滑块机构可靠性灵敏度分析

建立了曲柄滑块机构可靠性灵敏度分析模型,推导了机构尺寸参数可靠性灵敏度基于重要抽样法的求解公式,研究低速非连续接触和高速连续接触两种分析模型下铰链间隙对可靠性参数的影响.研究表明铰链间隙对机构运动精度可靠性及可靠性灵敏度计算结果影响很大,且随着机构运行速度的增加,这种影响更为显著.     

考虑间隙的发动机曲柄滑块系统动态特性仿真研究

发动机是汽车的核心部件,曲柄滑块机构是发动机中的重要的传递力和位移的机构。建立曲柄滑块系统的多刚体模型,并通过对系统的运动学机型分析,得到曲柄滑块系统的速度方程与加速度方程。分析转动副间的间隙,并通过建立系统的尺寸链,利用极限法计算得到考虑转动副间隙影响时滑块运动到上止点时的位置。分析发动机的压缩比,建立发动机压缩比计算公式,找到发动机压缩比与滑块上止点的位置、转动副间隙之间的关系。利用MATLAB/Simulink对曲柄滑块系统进行运动仿真,分别得到曲柄作匀速、匀加速运动时,滑块位移与输入的关系。根据仿真得到的滑块运动位移结果,分别计算考虑和忽略转动副间隙时发动机的压缩比。通过结果对比可以看出,由于转动副间隙的存在,减小了发动机压缩比,降低了发动机性能,不利于发动机燃油经济性。     

安装锥形刀具工作机构的动力学参数分析

安装有锥形刀具的工作机构在破碎介质时所承受的载荷,与介质的赋存条件、介质的物理机械性质以及工作机构的结构参数有关.在工程实践中必须掌握介质的相关参数,通过实验和计算机模拟,实现工作机构动力学参数的优化,达到改善整机模态和提高整机可靠性的目标.     

数值方法在铰链四连杆机构运动分析的应用

针对铰链四连杆机构运动设计解析法的复杂性,在建立机构运动几何方程的基础上,利用牛顿迭加法进行数值求解.通过对不同步长以及差分格式的选取比较,确定了计算杆件速度和加速度的合适的差分公式.运用Matlab语言强大的计算及图形可视化功能,获得了精确的数值结果和提高了设计的效率.     

Effect of flexibility on the dynamic stability of a four-bar mechanism

Dynamic behavior of flexible components of mechanisms is prone to instabilities which create resonant speed barriers. By considering small deformations superimposed on the steady dynamic state, equations governing evolution of disturbances can be obtained. For the case of mechanisms driven by periodic inputs these equations reduce to a system of coupled Mathieu-Hill equations for the amplitudes of modes of vibrations. Application of the Floquet theory determines the critical conditions of speed, geometry and material properties causing dynamic instability.     

应用吴方法求解平面四杆机构四点轨迹综合的探讨

主要探讨了用符号算法解决平面四杆机构四点轨迹综合问题。对于综合问题中出现的非线性方程组,利用吴方法求得特征列,从而求出其封闭形式解。这里给出了4点轨迹综合的数字例,得到了6套平面四杆机构。     

Dynamic and motion consistency analysis for a planar parallel mechanism with revolute dry clearance joints

The aim of the research was to introduce a methodology for dynamic response and motion consistency research on multibody system with multiple revolute clearance joints. An improved impact force model and a modified friction force model were introduced to evaluate the effects of impact and friction in clearance joints. A planar parallel mechanism which has two clearance joints in the left wing and the right wing was also used as an example. From the results based on different conditions, clearance has slight influence on the angular displacement and angular velocity, but obvious effect on angular acceleration. And with same clearance values of left wing and right wing, the motion consistency of the parallel mechanism is very good, which means the dynamic response of two wings is almost symmetrical. When the two clearance joints have different clearance values, the motion consistency and relative error between two wings are much obvious, especially the angular acceleration.     

球面四杆函数生成机构优化设计

为了提升连杆机构设计质量和机构运动性能,对球面四杆函数生成机构展开运动学分析,在考虑不确定因素影响下运用一次二阶矩法建立球面四杆函数生成机构运动精度可靠性模型,同时建立了以连杆机构函数输出运动误差的最大值、函数输出运动精度失效概率和函数输出误差均值与标准差平均值之和为目标函数的3种优化模型,并通过实例数值仿真对3种优化...     

平面四杆机构的可靠性分析

将诸原始误差均视为随机变量，对平面四杆机构具有杆长尺寸误差、铰链间隙误差及磨损量等各项随机变量分别进行了分析；应用微小位移的线性叠加原理综合出各项误差导致的机构运动输出总误差，建立了机构运动精度可靠性分析模型；利用计算机数字仿真技术，考察了机构中杆长尺寸误差和铰链间隙(或磨损)误差随机变量均值和方差的改变，对机构输出运动精度可靠度的影响，从中获得了一些有意义的结论。     

Modeling dynamic behavior of MDOF systems with multiple bilinear springs

A computational scheme is presented in this paper to simulate dynamical behavior of multiple degrees of freedom (MDOF) systems with multiple bilinear springs. In the proposed scheme, a bilinear spring is modeled using by two parallel springs - a primary spring and a secondary spring. The primary spring is an ordinary linear spring having identical stiffness in tension and compression, and is active for tension and compression. The secondary spring, whose stiffness characterizes the bilinearity, is active only during compression. It is employed in connection with the Newmark integration method and the linear complementarity problem (LCP) formulation to obtain time-domain responses of dynamical systems with bilinear springs due to initial disturbances and harmonic excitations. The scheme described in this paper is effective in dealing with the sudden transition from tension to compression and vice versa simultaneously for all bilinear springs. Numerical results for bilinear oscillators with finite bilinearity ratios and impact oscillators with an infinite bilinearity ratio show that the proposed bilinear spring model is accurate, generic and valid for bilinearity ratios ranging from zero to infinity. Orderly and chaotic behavior of viscously damped 3-DOF system under harmonic excitation is studied for a wide range of excitation frequencies and bilinear ratios to demonstrate the effectiveness and applicability of the proposed model for MDOF bilinear systems.     

一种新型平面连杆机构——四偏心机构

为扩大传统平面连杆机构的应用范围、丰富其结构形式,通过完全采用以偏心构件代替连杆,以转动副代替铰接,构成一种新型的四偏心式平面四连杆机构,即带有大转动副的微型平面四连杆机构.为促进此机构向实用阶段转化,给出了两种基本的结构形式,并对其进行了初步的结构分析、运动分析、CAE仿真以及实验验证.给出了各构件的基本尺寸关系和结构优化的方法,求出了从动构件的转角位移运动方程和曲线.通过仿真获得了与理论推导结果相同的从动构件的转角位移运动曲线;同时得出了此机构与传统平面田连杆机构的运动仿真轨迹曲线一致.指出了此机构相对于传统四连杆机构的特点和实施要点.上述分析证明此机构与传统平面田连杆机构的运动规律在本质上具有一致性.     

平面四杆导向机构的最优综合方法

选定一种十分理想的Burmester曲线计算方法 ,为给定连杆平面四个相邻位置的导向机构综合问题 ,编制出一套实用的不需提供机构初始位置的计算程序 ,可快速解得许多满足要求的平面四杆机构 ,使选择具有最合适结构、尺寸与传力性能的机构成为可能。该方法容易推广用于传动机构综合和多杆导向机构综合。