FURTHER DEVELOPMENTS OF MULTIPLE REFERENCE IMPACT TESTING

摘要

The advent of portable, inexpensive multiple channel data acquisition systems has made possible the implementation of a Multiple Reference Impact Testing (MRIT) method for Multiple-Input Multiple-Output (MIMO) Frequency Response measurements. MRIT combines the historical advantages of impact testing and MIMO testing methods. This method is particularly useful for trouble-shooting, field testing, and preliminary analysis purposes. This paper addresses two developments that enhance the utility of the MRIT method. The geometry of most test objects limits the possible impact locations and directions. To generate more descriptive mode shapes, a completion algorithm estimates the response for unmeasurable degrees of freedom. This paper includes some basic modal vector completion methods that are suitable for impact testing. This paper also describes signal processing techniques to improve the quality of impact testing measurements. These techniques include time domain windowing and procedures for removing periodic components for the data. The application of the MRIT method to test rotating machinery while in operation is illustrated. The data processing technique used to minimize the effects due to periodic excitation sources is demonstrated.