Study on Snap-Through-Type Nonlinear Dynamic Damper

本文从理论和实验两个方面研究了一种具有非线性弹簧的速断型动力阻尼器的减振特性。主要研究结果如下：1.理论分析考虑了由粘性阻尼和非线性弹簧组成的单自由度系统的阻尼器模型。弹簧的非线性用三次多项式表示，有两个稳定的平衡状态。(1)数值分析了无阻尼单自由度系统在非线性阻尼器作用下的冲击自由振动响应。研究发现，存在比线性系统具有更好的振动抑制效果的系统。(2)强迫振动的优化解略优于PQ理论的线性系统的优化解。混沌振动是一种常见的振动现象，但并不总是能对振动产生很大的抑制作用。2.实验分析制作了一种由两端有间隙的层合屈曲薄板和一个位于跨中的质量组成的卡扣式阻尼器。阻尼器设置在悬臂梁上，视为单自由度系统。(1)结果表明，冲击力作用下的振动响应与数值计算结果基本一致，阻尼器可以有效地抑制系统的振动。(2)结果表明，该阻尼器对不平衡引起的强迫振动响应也有抑制作用，在具有抑制作用的频率范围内，系统发生了混沌振动，说明该动力阻尼器对冲击力有较好的抑制作用。为了实际应用，需要对阻尼器结构进行改进。

Characteristics of suppressing vibration of a dynamic damper with snap-through-type nonlinear spring are investigated theoretically and experimentally. The result is described as follows :1.Theoretical analysisA damper model of a single-degree-of freedom system which consists of a viscous damping and a nonlinear spring is considered. Nonlinearity of the spring is represented with cubic polynomial and has two stable equilibrium states.(1) Impact free vibration response of the system where the nonlinear damper is attached to an undamped single-degree-of-freedom system to which is numerically analyzed. It is found that there are systems with the better effect of vibration suppression than linear systems.(2) The optimized solutions in forced vibration was a little better than those of the linear system by PQ theory. Chaotic vibration can be often seen, but it doesn't always lead to large suppression of the vibration.2.Experimental analysisA snap-through-type damper which consisted of laminated buckled thin plates with clearance ends and a mass at a center of the span was made. The damper was set up on a cantilever beam considered as a single-degree-of-freedom system.(1) It is found that the vibration response by impulsive force is in general agreement with the numerical result and that the vibration of the system can be suppressed by the damper.(2) It is confirmed that the forced vibration response due to unbalance can be also suppressed by the damper and that the chaotic vibration occurs over the frequency range with the vibration suppression effect.It is concluded that the dynamic damper proposed is effective for impulsive force. For practical application, an improvement in the damper structure is necessary.