Deriving patterns for the vibration-based damage detection in side frames of bogies

Abstract

Detecting damage in the incipient state is of crucial importance in monitoring the health of engineering structures. Approaching damage detection as an inverse problem is a common method when vibration-based techniques are used. It implies a precise a priori estimation of the modal parameters. We present in this paper a model to predict the frequency changes due to cracks in the side frames of bogies used to detect the welding defects in T-joints. To this aim, we model the structure and perform simulations using the SolidWorks software. The frequencies for the first thirteen modes are derived for the intact structure and the structure with different damage lengths and positions. By these tests, we first desire to find the optimal fixing of the side frame to reduce the number of vibration modes that are not of interest to the damage detection process. After finding the ideal fixing system, we derive patterns, for different defects, in the form of relative frequency shifts. Finally, we conclude about the damages that can be identified using the derived patterns, the conclusions being traced based on the measurability of the frequency changes.