Estimation of Damage Location of Beam Subjected to Impact Hammer Excitation Based on Nonlinear Wave Modulation Phenomenon

Abstract

This paper concerns the estimation method of damage location based on the nonlinear wave modulation demodulation which has attracted much attention in the field of structural health monitoring. When a structure containing a contact-type damage is subjected to a low-frequency vibration, a high-frequency wave which propagates through the damage may undergo amplitude and phase modulation at the damage location because the scatter characteristics of high-frequency waves in the vicinity of the damage may fluctuate in synchronization with the low-frequency vibration because of the contact acoustic nonlinearity. Since this modulation propagates through the structure with the group velocity, it may be possible to estimte damage location by measuring the modulation and performing an inverse analysis based on the wave propagation model. In this paper, a mathematical model of the modulation propagation on a Timoshenko beam is constructed, and by considering the damage as a source of the modulation, an estimation algorithm of damage location which utilizes the time difference between the modulated waves measured by sensor arrays located at both sides of the damage is proposed, and examined experimentally.