Nonlinear acoustics with low-profile piezoceramic excitation for crack detection in metallicstructures

Abstract

Structural damage detection is one of the major maintenance activities in a wide range ofindustries. A variety of different methods have been developed for detection of fatiguecracks in metallic structures over the last few decades. This includes techniques based onstress/acoustic waves propagating in monitored structures. Classical ultrasonic techniquesused in nondestructive testing and evaluation are based on linear amplitude and/or phasevariations of reflected, transmitted or scattered waves. In recent years a range of differenttechniques utilizing nonlinear phenomena in vibration and acoustic signals havebeen developed. It appears that these techniques are more sensitive to damagealterations than other techniques used for damage detection based on linear behaviour.The paper explores the use of low-profile piezoceramic actuators with low-frequencyexcitation in nonlinear acoustics. The method is used to detect a fatigue crack in analuminium plate. The results are compared with modal/vibration excitation performedwith an electromagnetic shaker. The study shows that piezoelectric excitation withsurface-bonded low-profile piezoceramic transducers is suitable for crack detection based onnonlinear acoustics.