多界面干摩擦系统的减振特性及设计方法研究

ON DESIGN AND DAMPING CHARACTERISTICS OF MULTI-INTERFACE DRY FRICTION DAMPER

作为一类非线性阻尼,干摩擦阻尼器的减振效果通常与激振力水平直接相关,且往往只在一个激振力水平下具有最佳振动抑制效果。为改善其"激振力-减振效果"特性,提出了设计多界面干摩擦系统的思路。从一类可描述扭转振动的集总参数模型出发,探讨了此类系统的可行性,并给出了无量纲的动力学方程组。其次,提出了一种改进的时/频转换方法,用以分析包含任意干摩擦界面系统的频域响应,考虑了每个干摩擦界面上可能出现的周期内"滑移"、"滑移-阻滞"和"阻滞"运动状态。同时,用相应的数值积分方法验证了该方法的正确性和在计算速度上的优势。在此基础上,分析了干摩擦界面的个数、临界摩擦力和质量对系统特性的影响,以二界面和三界面干摩擦系统为算例,阐明了采用多个干摩擦界面改善系统减振性能的机理和设计方法。

It was shown in current literatures that the performance of a dry friction damper would significantly change while the excitation level varies. This phenomenon originates from the non-linear nature of friction, and as a consequence, there is only one most suitable excitation level for an individual dry friction interface. The present work is devoted to extend the working range of a dry friction system with respect to the excitation level, by introducing multiple dry friction interfaces into the host structure. The torsional vibration of the host structure is considered, modeled by the Lumped Parameter approach and the Coulomb assumption. Firstly, the feasibility of such a system is discussed based on the derived non-dimensional dynamic equations. Secondly, an enhanced time/frequency alternating method is proposed, with a full consideration of the relative motions which could possibly happen in each dry friction interface. It is proved through a numerical integration method, that the proposed method is a precise and rapid tool for the solution of nonlinear systems in a frequency domain. The dynamic behavior of such a system was investigated via several groups of parameters, including the number of dry friction interfaces, the critical frictional forces and damper mass and etc. At last, the damping characteristics of a 2-interface system and a 3-interface system are presented respectively, showing the procedure of designing such a system.