The Comparison of Modal Analysis by Two Different Experimental Approaches

This paper presents the comparison of two different methods in the system identification. The experimental modal analysis and operational modal analysis are applied to a local structure of a storage/retrieval machine (S/R machine). The different vibration measurement approach and different theoretic analysis approach give us more information than only one approach. Through the result, the consistence of two approaches is found, and the vibrating integrality that is obtained from measurement under normal operating condition is better than that is obtained from measurement during exciting the structure by a hammer. From the system frequency response functions that obtained by measurement during exciting the structure by a hammer, the high vibration response frequencies are indicated clearly. On the base of the two experiments, the vibration properties of local structure of a storage/retrieval machine are thoroughly grasped. This is a foundation of structure modification to reduce the vibrating noise of storage/retrieval machine during operating conditions.