Identifying Modes of Large Structures from Multiple Input and Response Measurements

When mode shapes are identified from transfer function measurements, it is usually assumed that the structure can only be excited or its response measured at a single point. Hence, this method has become known as the “single point” testing method.

This paper discusses a new testing and data processing technique for obtaining modal parameters which does not require that the transfer function measurements be made using a single excitation or response point. For large structures this “multiple point” testing technique is in many cases, necessary for obtaining measurements of sufficient quality to identify the modes of vibration.