Experimental Realization of System-Level Vibration by Use of Single Component Based on Virtual Boundary Condition Concept

Abstract

In order to meet the requirement of less vibration and less noise of complex machine, such as automobile, the system-level vibration test is carried out in spite of huge cost and time, which is conducted only when all components are able to be assembled. Although the vibration of individual component alone is different from the system-level, but a sophisticated component test is aimed to realize the system-level vibration at early development stage.

In this paper, a virtual boundary concept where the single component involved vibration source is excited by common uni-axial electro-magnetic exciters at proper point and direction with proper feed signal is proposed for experimental realization of the system-level vibration.

First the FRFs of the component are measured solely and the operating force can be identified based on operating vibration of the component. Then the FRFs of the rest component of the system and the system external force are given and consequently the transmitted forces through the connection points between the component and the rest can be determined. Therefore the target system-level vibration of the component can be predicted and the proper point and direction with proper feed signal of the exciters can be determined.

After verification by simple numerical model, the proposed method is applied to a Heating, Ventilating and Air Conditioning, HVAC component of automobile involved a blower motor. The difference of vibration and noise as well between the HVAC component and system level is revealed and finally two exciters are used to realize the system-level vibration and noise.