Comparison and analysis of two Coulomb friction models on the dynamic behavior of slider-crank mechanism with a revolute clearance joint

The objective of this study is to investigate the effects of the Coulomb dry friction model versus the modified Coulomb friction model on the dynamic behavior of the slider-crank mechanism with a revolute clearance joint. The normal and tangential forces acting on the contact points between the journal and the bearing are described by using a Hertzian-based contact force model and the Coulomb friction models, respectively.The dynamic equations of the mechanism are derived based on the Lagrange equations of the first kind and the Baumgarte stabilization method. The frictional force is solved via the linear complementarity problem(LCP) algorithm and the trial-and-error algorithm.Finally, three numerical examples are given to show the influence of the two Coulomb friction models on the dynamic behavior of the mechanism. Numerical results show that due to the stick friction, the slider-crank mechanism may exhibit stick-slip motion and can balance at some special positions, while the mechanism with ideal joints cannot.

Kinematic Analysis of Elliptic-Gear & Eccentric Slider-Crank & Uniform-Pitch Screw Weft-Insertion Mechanism

In order to analyze the kinematic performances of elliptic-gear & eccentric slider-crank & uniform-pitch screw weft-insertion mechanism proposed by us,kinematic mathematic models of the mechanism were established,and an aided analytic software was compiled.Influences of some important parameters on the kinematic characteristics of the mechanism were analyzed.A group of preferable parameters were obtained according to the software and some requirements.Comparisons of kinematic performances were made between the proposed mechanism and the variable-pitch screw insertion mechanism of C401 rapier loom manufactured by Vamatex Corp in Italy.The results show that the proposed mechanism can meet the requirements of inserting wefts.

A method to calculate and counterbalance the inertia force of slider-crank mechanisms in high-speed presses

A new method to calculate and counterbalance the inertia force of slider-crank mechanisms in high-speed mechanical presses was put forward. By analyzing the kinematic characteristics of a center-located slider-crank mechanism whose crank rotates at a constant angular velocity,the kinematic parameters of the slide,connecting rod and crank were formulated approximately. On the basis of the results above,three inertia forces and the input moment in the mechanism during its idle running were investigated and formulated by dynamic analysis. A verification experiment was performed on a slider-crank mechanism at a high-speed press machine. The forces derived from the established formulas were compared respectively with those obtained by the ADAMS software and the classical method of connecting rod mass substitution. It was experimentally found that the proposed formulas have an improved performance over related earlier techniques. By use of these results,a 1 000 kN 1 250 rpm four-point high-speed press machine was designed and manufactured. The slide of this press is driven by four sets of slider-crank mechanisms with symmetrical layout and opposite rotation directions to counterbalance the horizontal inertia forces. Four eccentric counterbalance blocks were designed to counterbalance the vertical force after their mass and equivalent eccentric radius were formulated. The high-speed press machine designed by the proposed counterbalance method has worked with satisfactory performance and good dynamic balance for more than four years in practical production.

基于Ansys的曲柄滑块机构的运动学分析在教学课程中的应用

在机械原理的教学中,曲柄滑块机构的设计原理与方法是重点和难点问题,传统的实物实验对曲柄滑块机构的种类、复杂性都有很大的限制,不利于学生对曲柄滑块系统运行规律的掌握。基于此,利用Ansys中的workbench建立了曲柄滑块机构运动仿真模型,通过对模型进行分析设置,对典型曲柄滑块机构进行运动仿真,得出了曲柄滑块机构的位移及应力、应变的分析结果,为机械结构仿真教学提供了有效的方法。

含柔性连杆的曲柄滑块机构动力学分析与实验研究

为了研究柔性连杆、带有固体润滑涂层MoS_2的铰链接触副对含间隙铰链机构的动力学特性的影响规律,以曲柄滑块机构为研究对象,使用Adams软件进行数值仿真分析,研究了柔性连杆材料、铰链间隙、铰链接触副材料和铰链接触副表面固体润滑涂层对曲柄滑块机构动力学特性的影响。通过搭建与数值仿真参数一致的含间隙铰链的曲柄滑块试验台,试验验证了柔性大的连杆、较小的间隙值、接触刚度较小的接触副材料能够减小机构的振动,带有涂层的铰链能够有效减小接触面的磨损量。试验结果和数值仿真结果较为一致,能够有效的反应各种工况对含间隙机构的影响规律,为固体润滑涂层在航天领域中含间隙铰链接触副展开机构的减振抗冲击研究提供理论基础和试验依据。

巴斯噶蜗线齿轮-曲柄滑块式引纬机构设计

为了优化引纬机构性能,在现有引纬机构的基础上进行了创新研究,提出了一种巴斯噶蜗线齿轮-曲柄滑块组合传动的新型引纬机构。为便于分析新型引纬机构的运动特性,基于数值分析和几何图形建立了该机构的运动学数学模型,并利用MatLab建立了该引纬机构的可视化设计分析平台。为分析各设计参数对该引纬机构的运动特性的影响,以剑带加速度为优化目标,利用正交试验优化方法对该机构进行优化分析,得出展长与发生圆直径比值、连杆长度与曲柄长度比值和传剑轮半径这3个参数对引纬运动规律有较大影响;变性系数和丝杠螺距则影响不大。研究结果可为全面研究引纬机构运动特性提供参考意见。

可变幅振动式咖啡收获机设计与试验

针对咖啡人工采收成本高、大型机械采收困难等问题,以曲柄滑块式传动机构为基础,设计一款小型可变幅振动式咖啡收获机。通过建立咖啡果实-果柄的脱落力学模型,分析得到果实脱离果柄的条件,依据曲柄滑块的设计方式,构建传动结构的运动简图与计算公式;采用ANSYS Workbench与Adams软件,进行模型的动力学仿真分析;以传动结构的曲柄长度、摇杆长度和转速为试验因素,惯性力为试验指标,进行三因素三水平的正交试验与响应曲面分析,建立惯性力二次多项式回归模型,以果-柄结合力5.25~7.16 N为优化目标,确定收获机的结构参数和工作参数。结果表明,在保证传动结构运行状态平稳的优先原则下,得到咖啡收获机结构设计的最优参数组合为曲柄长度15 mm,摇杆长度100 mm,转速700 r/min;通过样机试制与田间试验,转速在700 r/min左右,总体的作业效果良好。研究为后续的咖啡机械化收获提供参考。

内燃机中的曲柄滑块机构在机械中的应用研究

内燃机中的曲柄滑块机构采用了平面连杆机构,它是组成机械最常用的传动机构之一,在各种机械中有着广泛的应用,本文分析了曲柄滑块机构及其演化机构在内燃机、公交地铁车门、牛头刨床、飞机起落架和惯性筛中的应用,画出了机构运动简图,并对其性能进行了研究,为曲柄滑块机构在机械中的应用提供参考。

基于调和函数的偏置曲柄滑块机构非线性诺模图设计

文中给出了偏置曲柄滑块机构的非线性诺模图。首先,对机构基本方程引入无量纲参数和过渡函数,将机构数学模型整理成适合诺模图求解的标准形式;其次,对过渡函数采用构造调和函数并解析的策略,寻求较优尺度模量,弱化和规避关键标尺刻度的非均匀分布和过度集中现象;最后,使用两种不同类型无量纲参数的案例,对所给非线性诺模图进行验证。结果表明:该诺模图不仅可直接用于快速设计不同目标的偏置曲柄滑块机构,还可对所做设计的正确性与合理性予以快速校验。

基于SolidWorks的曲柄滑块机构运动分析与曲柄有限元分析

为掌握曲柄滑块机构运动特点以及曲柄的强度,对曲柄滑块机构进行运动分析,推导滑块的位移、速度、加速度方程。再使用SolidWorks软件,完成机构运动仿真,分析滑块位移和加速度运动特性。对曲柄受力分析,并通过SolidWorks Simulation对曲柄进行有限元分析,对应力、变形、安全系数云图进行分析,有利于指导曲柄零件的结构设计。

Load spectrum analysis for combined frame of closed high-speed press

Based on the basic theory of mechanics,kinematic and dynamic analysis for a slider-crank mechanism with a balance mechanism is performed.The theoretical formula of the load spectrum for the interaction between the crank shaft and the bearing seat of the upper beam is achieved by approximately simplifying the mechanical model of the crank shaft.The simulation for the load spectrum data of combined frame under the operating conditions of blanking or piling is performed using Matlab and the law of the load spectrum curves under these two conditions is analyzed.The simulation results show that under a no-load condition,the load spectrum curves of the interaction between the crank shaft and the bearing seat of the upper beam present a form of periodic sine wave and under the piling condition,the load spectrum curves of the interaction between the crank shaft and the bearing seat of the upper beam present a form of periodic pulse wave.The simulation results can provide a theoretical foundation for the load determination during the process of analyzing the dynamic characteristics on the combined frame of a closed high-speed press through the finite element method.

Design and Analysis on Compression Mechanism of Small Square Bales of Sugarcane Leaf Baler

With more and more attention paid to comprehensive utilization of agricul-tural biomass resources, environment pol ution caused by large-scale burning of sug-arcane leaves can be effectively avoided, and it is urgent to resolve storage issue of sugarcane leaf. Through referring to the relevant domestic baler models and re-search findings, preliminary design and analysis were conducted on key components compression mechanism of smal sugarcane leaf baler, involving the open compres-sion principle for sugarcane leaf square baler, determination of the crank slider-type compression mechanism and the main parameters such as crank length, compres-sion frequency, feed rate and feed inlet length. Based on SolidWorks software, this paper established the 3-dimensional models of slider-crank type compression mech-anism, and imported it into ADMAMS software for the motion simulation analysis, to establish the foundation for the design and manufacture of subsequent smal sugar-cane leaf square baler prototype.

船用压缩机传动结构分析

船用压缩机的减振降噪以往主要是通过增加减振装置、加强筋板或优化曲柄连杆结构等途径解决。基于船用压缩机减振降噪的需求,设计开发了曲柄圆滑块传动机构,从传动结构角度来降低船用压缩机的振动噪声。建立了机构的三维模型,并基于含间隙的运动副对传动结构做了仿真分析。

传动角最优的曲柄滑块机构多变量优化设计

在给定的设计要求范围内,希望设计出的机构具有最优的有效力传动性能.通过对曲柄滑块机构的几何关系和工作行程传动角的分析,确定了曲柄滑块机构的设计变量和工作行程最小传动角公式,建立了以工作行程最小传动角最大为目标的多维变量非线性优化数学模型,并给出算例,通过对比计算验证了提出的传动角最优的曲柄滑块机构多维变量优化设计方法.在行程速比系数、滑块行程和偏距等没有精确要求的情况下,为提高曲柄滑块机构有效的力传动性能,提供了一种实用的方法.

基于曲柄滑块机构原理导航的农业机器人设计

研究开发了一种自动导航果园用履带式移动机器人,作为果园精细化作业的移动平台。机器人采用基于曲柄滑块机构原理的导航方式,以导航机构检测的姿态角和位置角作为输入量设计了模糊PID控制器。试验表明,机器人以0.15 m/s的速度直线行走时,最大跟踪误差小于0.02 m;机器人转弯半径为2 m时,最大跟踪误差小于0.05 m。

饲草压捆机压缩机构动态仿真

在传统的运动及动力分析的基础上 ,采用MATLAB/Simulink进行压捆机压缩机构动态仿真 ,获得了任意时刻的速度、加速度、维持曲柄匀速转动所需的扭矩和机构之间的作用力 ,为压缩机构的设计提供了重要的数据 ,可视化的仿真结果便于观察研究。

4L-4.0型稻麦联合收获打捆复式作业机设计与试验

为了使稻麦联合收获机在工作过程中能够完成收获、打捆复式一次作业,研制了一种稻麦联合收获打捆复式作业机。该复式作业机在保证联合收割机正常工作效率的同时,也实现了稻麦秸秆的不落地打捆功能。该文对该复式作业机整体配置、传动系统、下喂入机构以及压缩机构等关键部件进行了设计和计算。该复式作业机结构形式为自走式,具有更好的田间通过性及更小的转弯半径,同时可靠性及工作效率均符合要求。田间试验结果表明：4L-4.0型稻麦联合收获打捆复式作业机的成捆率达到98.3%,规则草捆率达到94.7%,抗捆率达到90%,草捆截面尺寸达到40 cm×50 cm×60 cm,草捆密度达到了190-200 kg/m^3。该研究为中大型方捆收获打捆一体机的研究提供参考。

考虑连杆柔性和运动副粘性摩擦的曲柄滑块机构的动力学建模及计算

建立了考虑连杆柔性和运动副粘性摩擦的曲柄滑块机构的动力学数学模型 ,并对一个算例进行了数值仿真 ,结果表明 。

考虑杆件柔性的间隙机构系统磨损分析

基于机械系统动力学分析软件ADAMS建立了含多间隙曲柄滑块机构的动力学模型,利用冲击函数理论模拟间隙处的接触碰撞作用,详细研究了构件柔性和铰链间隙对机构系统动力学特性的影响,并应用Archard磨损模型对间隙运动副的磨损进行了预测。当考虑杆件柔性时,应用ANSYS程序创建连杆的有限元模型,取连杆的前五阶模态导入ADAMS中建立含柔性连杆的多间隙机构动力学模型并进行动力学仿真计算,结果发现,考虑杆件柔性时的间隙机构系统动态行为在很大程度上趋于理想机构,在曲柄转动一个周期的过程中间隙运动副除在几个特定的位置处发生了较大的碰撞外,轴销与轴套均保持连续接触,且预测所得的磨损量也较小。

脉动血流发生器非圆齿轮-曲柄滑块式驱动机构设计与分析

为使脉动血流发生器产生稳定的脉动性血流,提出了一种新型非圆齿轮-曲柄滑块式驱动机构,运用非圆齿轮副和曲柄滑块机构的组合传动来实现血流的脉动。在满足人体血流脉动前提下,为使设计的机构运行平稳,采用2段三次Hermite插值多项式来对该机构输出构件的加速度曲线进行拟合,再由加速度曲线方程及其边界条件推导出速度、位移和跃度曲线方程,运用拟合得到的输出构件运动学曲线方程推导出非圆齿轮副节曲线反求模型。根据实例求解分析得到的机构参数进行三维建模和虚拟样机实验,对比虚拟仿真实验和理论分析结果,发现所设计机构能够按照预期规律实现脉动血流,且该机构具有良好的运动学特性,同时验证了所构建的运动学曲线方程及所建立的运动学分析模型的正确性。