间隙铰链对平面机构碰撞动力学特性影响分析

Effects of clearance joint on impact dynamic characteristics of planar mechanisms

为了研究间隙铰链对机构动态性能的影响,建立了一种含轴向尺寸的线接触碰撞铰模型,在此基础上提出一种改进的非线性法向碰撞力模型和修正的切向库伦摩擦力模型,以平面含间隙铰链曲柄滑块机构为研究对象,通过不同间隙值下的滑块加速度、间隙铰链处接触力、加速度频谱以及速度-加速度相图分析,研究了间隙值对机构碰撞动力学特性的影响规律。研究结果表明:间隙会导致机构动态性能出现明显的振荡现象,且随着间隙值的增大,振荡加剧、振荡幅值上升,但振荡频率降低;同时,在间隙铰链的影响下,机构动态特性呈现出非线性现象,且间隙越大,非线性现象越明显。

Here,the effects of clearance joint on impact dynamic characteristics of planar mechanisms were studied. At first,a line-contact impact joint model with axial sizes was established. Based on an improved nonlinear normal impact force model and a modified tangential Coulomb friction force model,the effect laws of clearances on impact dynamic characteristics of a planar slider-crank mechanism were studied through analyzing slider acceleration,clearance joint＇s contact force,acceleration frequency spectra and velocity-acceleration phase diagram under different clearances.The results showed that the larger the clearance,the bigger the oscillation amplitude of the mechanism ＇s dynamic characteristics,and the lower the oscillation frequency; the larger the clearance,the more nonlinear the mechanism＇s dynamic characteristics.