An indicator for the assessment of isolation performance of transient vibration

It is known that the commonly used performance indicator for vibration isolation - force transmissibility - over-simplifies the vibration problem. Therefore, Mak and Su propose a power transmissibility approach that includes the effect of floor dynamics and the interactions of the mounting points between machine and floor. However, their model does not consider transient vibration excitation. The question motivating this study is the occasional problem which arises due to the sudden or frequent starting and stopping of vibratory machines. In this paper, a transient power transmissibility approach is proposed to assess the performance of isolators in a transient vibration excitation. A spring-mass-movable floor system is considered in the simulation, and the spring isolator is first selected using the steady-state power transmissibility approach of Mak and Su. A system disturbed by two transient excitations as typically experienced by building services equipment is then analyzed. The results indicate the necessity of using transient power transmissibility in the selection of isolators for a transient vibration.