Theoretical analysis of two stage shock isolation mount with switchable stiffness control

Resumen

Two-stage vibration mounts are a two degree of freedom system that can improve high-frequency isolation at the cost of added mass. However, the shock response and isolation characteristics of these mounts have not been previously studied. This paper presents a theoretical study of a two-stage mount under shock excitation. The shock response is evaluated in terms of the mass ratio between the two stages of the mount. It is demonstrated that improved shock isolation can be achieved depending on the value of the secondary mass. Furthermore, a variable stiffness strategy is applied considering an on-off switching logic between a high and a low stiffness value during residual vibration. The effects of using the proposed strategy are investigated when applied in the first, second, and both isolation stages. It is found that a passive two stage mount can improve shock isolation and that the use of switching stiffness further improves the isolation performance, particularly in the residual stage where it acts as added damping. The main contribution of this work is to propose a novel semi-active isolation model based on two existing approaches that can lead to better shock isolation.