拍频激励下的冲击钻进机械系统动力学特性研究

Research on Dynamics of an Impact-progressive Mechanical System by Beat Frequency Excitation

考虑系统的振动和钻进运动,建立了能够将高频低幅激励转化为低频高幅响应的冲击钻进机械系统的力学模型。分析了系统部件在碰撞以后出现"同步"和"非同步"运动的条件。采用了具有低频调制激励与振动系统固有频率(所期望的低频)吻合以及只用调制波正值部分激励质量块M2这两种特征的拍频运动激励,结果表明,该激励能够产生有效的冲击力,即锤击效应。给出了两种能够获得稳定钻进运动的途径。

A mathematical model of impact--progressive mechanical system accounting for the motions of vibration and progressive was developed. That can transfer a high--frequency low--ampli- tude excitation into low--frequency high--amplitude response. Conditions for synchronous and non-- synchronous motions of impact components immediately after the impact were studied. A special beat frequency kinematic excitation was used, which has two distinctive features. （~）the low--frequency modulated excitation was tuned to the natural frequency（which was the desirable low--frequency） of the vibratory system;（~）the excitation was asymmetric,i, e. only positive part of the modulated signals excited the mass M2. The results indicate that effective impact forces,i, e. hammer effect, are generated by the excitation. Two different ways to achieve a steady progression were explored.