Nonlinear Vibro-acoustic Interactions for Crack Detection in Beams

TLDR: In this paper, two-dimensional models of beam with non-propagating cracks are investigated and the results show that nonlinear phenomena investigated depend not only on excitation amplitude but also on crack position, sensor location and boundary conditions.

Abstract: Recent years have shown a growing interest in damage detection methods based on damage-related nonlinearities in structures. In the paper, the numerical simulations of two techniques – classical Higher Harmonic generation and Vibro-Acoustic Modulation - are presented and validated experimentally. Two-dimensional models of beam with non-propagating cracks are investigated. The focus is on bi-linear breathing crack behavior, which was modeled as a contact between crack faces. This phenomenon is known as crack breathing. Numerical simulation results show that nonlinear phenomena investigated are particularly strong in the vicinity of the crack. A number of aluminum beam specimens with different crack lengths and locations are investigated experimentally to validate numerical simulations. Signal responses were measured at several positions using piezoceramic sensors. The results show that nonlinear phenomena investigated depend not only on excitation amplitude – as expected – but also on crack position, sensor location and boundary conditions. doi: 10.12783/SHM2015/181