Contribution analysis of vibration mode utilizing operational TPA

Abstract

Operational transfer path analysis (OTPA) calculates contributions of reference points to response point vibration by using only operational data. Through OTPA, effective interior noise and vibration reduction are achieved by applying intensive countermeasure to the high contributing part. However, it becomes difficult occasionally when many reference points have similar contributions by a vibration mode. In this case, obtaining high contributing vibration mode and considering how to reduce the mode become important information. In this study, we attempted to calculate the vibration mode contribution by modifying OTPA. Principal component calculated in OTPA procedure is composed of correlated vibration factors among reference points. We then considered the relationship between the principal component and the vibration mode, and associated the principal components with the vibration modes of a test structure. As a result, high contributing vibration modes to the response point could be found. In addition, information about which side of the structure (response or reference side) had better to be measured intensively was also obtained by evaluating the influence of each principal component to the response point (principal component transfer function). Finally, Several countermeasures were applied to the structure considering the principal component and vibration mode contributions. The result shows effective vibration reduction at the response point could be carried out. Through these procedures, the modified OTPA became more useful tool for applying effective countermeasure.

Keywords

• transfer path analysis
• principal component
• vibration mode
• transfer function
• contribution