【作者】 刘柏希；

【导师】 刘宏昭；

【作者基本信息】 西安理工大学 ， 机械设计及理论， 2004， 硕士

【摘要】 由于机械设备的高速、轻量化发展，机构中运动副的阻尼已成为研究机构系统动力学响应时不可忽略的因素。如何建立考虑运动副阻尼的系统动力学模型是当前众多学者研究的重点。本文的主要内容如下： 以平面弹性四连杆机构为研究对象，运用KED(Kineto-Elastodynamics)方法推导出了连杆机构的系统动力学方程；在此基础上，将运动副阻尼等效为粘性阻尼，导出了包含运动副等效粘性阻尼系数的系统动力学方程。 为了获得运动副的等效粘性阻尼系数，对刚性单自由度转动副转轴的运动微分方程进行了推导，并由此导出了转轴角速度的理论表达式；通过对转动副转轴在衰减过程中的角速度的测量，拟合出了转轴角速度的表达式；比较角速度的理论表达式和拟合表达式，得出了运动副阻尼的等效粘性阻尼系数。 引入求解线性微分方程的状态空间法，并对其求解时变系统运动微分方程的具体步骤进行了推导；在此基础上将实测获得的运动副等效粘性阻尼系数代入系统动力学方程，求解后获得了考虑运动副阻尼的平面弹性四连杆机构的仿真结果；结果表明运动副的阻尼在一定程度上对振动具有抑制作用。 引入时间序列法对悬臂梁的模态参数进行了辨识；以三自由度质量—弹簧系统的模态参数辨识为例对此辨识方法及所编程序进行了验证。 利用Matlab语言编制了相应的求解机构运动学、动力学问题和应用时间序列法辨识模态参数的程序。更多还原

【Abstract】 With the increment of the operation speed of machines and the reduction of the mass of components, the joint damping has already been the important factor in the mechanism’s dynamic research. Therefore, How to provide an effective model to describe the dynamic characteristics of the system with joint damping is the focus of current dynamic study of mechanism.In this thesis, by means of the Lagrange function, the finite element dynamic equations of the beam element are deduced. Then all the element dynamic equations are assembled into the system dynamic equation through using the Kineto-Elastodynamics theory. The dissipation force derived from joint damping is applied as excitation force of the linkage system. Substituting it into the established system dynamic equation, the system dynamic equation with the equivalent viscous damping coefficient of the joint damping is derived.In order to obtain the equivalent viscous damping coefficient of the joint damping, the angular velocity of the shaft of joint is measured during attenuation. Based on the experiment data of the angular velocity, the expression of the angular velocity is fitted by means of the least square method. Comparing the fitted expression with the established theory expression of the angular velocity, the equivalent viscous damping coefficient is gained.The closed form algorithm of the state space method is employed to solve the system dynamic equation with time-varying coefficients. The dynamic problem of a linkage mechanism with four joints is taken as example to show that the presented models and methods are correct and practicable.The time series method is introduced to identify the modal parameters of a clamed beam. A spring-mass system with three degree-of-freedom is taken as example to show the correctness of the method and the program compiledfor this method.Lastly, computer programs for the dynamic analysis and time series method are compiled in Matlab.更多还原