刚体-弹性支承系统振动解耦评价方法分析

刚体-弹性支承系统多自由度振动的耦合程度评价方法是进行系统固有振动解耦设计的重要基础。对已有的基于耦合刚度、基于振型向量和基于系统动能分布的三种模态振动解耦评价方法进行了系统的分析,指出了各种方法的特点和不足之处,进而采用系统广义惯性力或广义弹性力做功的概念,提出了基于系统振动模态示功向量的振动解耦程度评价方法,具有物理意义准确、量纲统一的优点,适于评价具有不同类型振动响应量的模态振动的解耦程度,是对原有基于系统动能分布的评价方法的完善和推广。并列举两例来说明所提方法的有效性及其物理概念的严密性。

EVALUATION APPROACHES OF VIBRATION-MODE UNCOUPLING FOR MULTI-DOF RIGID-BODY WITH ELASTIC MOUNTING SYSTEM

The evaluation of vibration-mode uncoupling degree is a fundamental issue for vibration isolation design of multi-degree-of-freedom rigid-body-elastic-mounting system.Three conventional evaluation approaches,i.e.,the coupling-stiffness-based method,the vibration-mode-shape-vector-based method and the kinetic-energy-distribution-based method,are analyzed,and the deficiencies of conventional methods are pointed out.Using the concepts of the work which is done by the generalized inertia forces or by the spring rebound forces,the kinetic-energy-distribution-based method is modified to a modal-work-index-based method.The modified method is clearer in physical concept and is consistent in units for evaluation quantities,the modal-work is an appropriate measure to decouple the rigid mode and is applicable to vibration systems with different types of generalized coordinates,such as translational and rotational displacements.The modified method is an effective remedy and extension to the kinetic-energy-distribution-based method.Two examples are illustrated to exhibit the efficiency of the newly raised measure and its precision of the physical concepts.