Damage detection and localization in loose bolted joints

In this paper damage detection and damage localization of imperfect bolted joints is studied numerically using three-dimensional explicit finite element simulations. The study is focused on using contact acoustic nonlinearity (CAN) due to interaction of asymmetric guide waves (A0) with imperfect joint surfaces for detecting and locating imperfect joints. Numerically obtained data are processed and it is shown that the CAN can detect and locate defects. The finite element model is used to study several case studies. It is demonstrated that finite element can predict propagation of guided waves in bolted joints. CAN is used for locating the loose bolt. It is demonstrated that FE model followed by signal processing approach used in this study can successfully and accurately detect and locate the imperfect joints. Overall, the findings of this study provide improved physical insights into using CAN for detecting and locating imperfect joints, which can be used to further advance damage detection techniques using nonlinear guided waves.