Practical identification technique of characteristic matrices of structures from frequency response function

(Improvement of accuracy by the use of foresight information of the objective system)

Abstract

As a basic study to estimate dynamic characteristics of structures such as carbody of railway vehicles and in order to improve their vibration characteristics, this study is aiming to identify mass, stiffness and damping matrices (called characteristic matrices) from frequency response function obtained by some realistic excitation testing of target structures. In this report, a theoretical procedure to estimate those matrices from frequency response functions obtained by single driving point is firstly described. Then the procedure is validated numerically using a nine degrees of freedom kinetic model. To improve the accuracy of identified characteristic matrices, using foresight information concerning with mass matrix are proposed. It has been demonstrated that introducing the foresight information is effective and good agreement has also been observed between exact and identified FRFs (Frequency Response Functions). In addition, the influence of the noise contamination in measured data is discussed. Although this proposed method is relatively robust against noise contamination, it has been found that accurate modal characteristics estimation of the target structure is important to identify characteristics matrices successfully.