Development of modal testing and SDM techniques

Abstract

A model testing and a Structural Dynamics Modification (SDM) programs are developed to understand the dynamics of a structure experimentally and to predict the dynamics of an analytically modified structure, using a micro-computer and a dual channel signal analyzer. The modal parameters - damping ratios, damped natural frequencies and mode shapes - are estimated from the measured frequency response data using the developed modal testing program. The developed SDM program, which requires the modal parameters of an original structure and involves a common modeling procedure, consists of hardware modification, resonance specification and substructuring. The main programs developed for SDM include the routines for manipulating matrix algebra, solving eigenvalue problem, finding complex roots and creating modification matrices. To evaluate the developed programs several test structures are built and tested in the laboratory. It is shown in the experiments that the developed programs work well with the test structures.