Using passive frequency response functions generated using the Operational Round Trip method to make vibration predictions at remote points

The Round Trip method was derived as a means to acquire point mobility frequency response functions at passive locations, where the term 'passive' specifies that no external known force has been applied. This allows frequency response functions to be generated at locations where the degree of freedom cannot be excited by conventional means. Vibration produced by operational sources can increase signal-to-noise ratios in large complex structures and improve the quality of the measured frequency response functions, where it can be challenging to effectively excite the system by conventional experimental means. In this study, the application of a modified version of the Round Trip method that is based on transmissibility functions, termed the Operational Round Trip method, has been investigated to determine whether forces generated by an operational source, such as a motor, could be used to generate frequency response functions at and between passive locations. Frequency response functions generated using this method have been coupled with the estimated blocked forces of an operational source to make response predictions at remote positions. Predicted responses were compared against measured responses and were shown to match those closely.