Application of Modal Testing in Model Updating of Structures

Apart from the analytical approach to develop a dynamic model for a mechanical structure, another approach is to establish an experimental model for the structure by performing vibration tests and subsequent analysis on the measured data. This process is known as ‘Modal Testing’. During the last three decades or so, modal testing has developed both in theory and in practice. One of the most important applications of modal testing is the validation of the mathematical models of dynamic structures by comparing the experimentally driven modal parameters with those of analytical models. Once the analytical model is validated, it can be used with confidence for further analysis such as response prediction, structural coupling, stress analysis, life time prediction, etc. In this article, the advantages and disadvantages (or limitations) of one of model updating methods are discussed. A 6 DOF lumped parameter system, is employed to investigate the effectiveness of the "Inverse Eigensensitivity Method" (IEM). Firstly the experimental data were simulated using the analytical model. Secondly error locations are found using macro elements. Finally, experimental dynamic properties obtained from the simulated experimental data are compared with the results of the finite element analysis and mass and stiffness error matrices are calculated by using Inverse Eigensensitivity Method" (IEM).