Low Temperatures Influence on the Lamb Waves in Aluminum Structures

Abstract

their capability to detect and localize online and offline defects in the structures. The performance of this method such sensitivity and the precision for defect localization could be influenced by environmental parameters. One of the most important of these parameters is the temperature. It is affecting the whole chain of the defect detection method, from wave generation to signal acquisition. The temperature can affect piezoelectric actuators and transducers electro-mechanical performances and the mechanical coupling between them and the monitored structure and also the mechanical guided waves propagation parameters thru the structure. We have performed and experiment for establishing how big is this influence on the whole system. The structure used is aluminum plates which has piezoelectric actuators and transducers (PWAS) glued to them on different distances between them. Each of these PWAS are used as transmitter or as receiver at a time for generating or for receiving the Lamb waves thru structure. The signal acquisition has been done for few frequencies such as S0 and A0 dominant frequencies and other values between them on temperatures between 00C and -700C. The reason for choosing this temperature range was due to the fact the most aircrafts are flying on high altitude where these temperatures values are common. These results shows important changes of the received signal with temperature variation. This is an important fact which needs to be taken into consideration for structure health monitoring for the optimization of the method used.