Damage detection in composite structures with high-damping materials using time reversal method

This paper presents a new damage detection technique for use in highly damped composite structures using the time reversal method with different excitation amplitudes. A Rayleigh damping model was used to numerically explore the influence of damping on the time-reversibility of Lamb waves. In the experimental investigation, high-damping absorptive materials were introduced between a sensing path on a composite plate. Excitations of different amplitudes were applied on transducers to generate different energy levels for interrogating waves. It was found that high damping broke down the time-reversibility of the Lamb waves. Both the damped and the damaged sensing paths had much higher damage indices than the pristine path under a large excitation. However, with the decrease in excitation amplitude, the damage indices of the damaged path obviously decreased, whereas those of the highly damped path remained almost constant. The proposed method can effectively detect damage in composite structures and avoid false alarms from the presence of high-damping materials.