Importance of selecting a suitable analysis frequency range in impact force identification for automobile test rig

Abstract

In this study, the effectiveness of selecting a suitable analysis frequency range in impact force identification is highlighted. A methodology that utilizes Operating Deflection Shape (ODS) analysis, Modal Analysis (MA) and Modal Transformation Method (MTM) to evaluate the dynamic force in three cases of analysis frequency ranges was presented. These three cases are the over??estimated, even-estimated, and under-estimated cases, which consist of higher, similar and lower analysis frequency range respectively, compared to the actual excitation frequency range. The performance of this approach was demonstrated via experiment. A Perspex plate with four ground supports was used as the automobile test rig. By measuring the acceleration response and Frequency Response Function (FRF) of the test rig, the time history of unknown force was recovered by the proposed method where the impact location was known in advance. It showed that the force identification result for even-estimated case falls within acceptable range while the force identification result for over-estimated and under-estimated cases is not acceptable.