Engineering Mechanics Institute Conference 2013

Full Program »

Detection of thermal fatigue in composites by second harmonic Lamb waves

DOC Abstract
View File

Weibin Li
School of Mechanical Engineering, Pusan National University
Korea, Republic Of

Younho Cho
School of Mechanical Engineering, Pusan National University
Korea, Republic Of

Jan Achenbach
Center for Quality Engineering and Failure Prevention, Northwestern University
United States

Nonlinear ultrasonic technique has been explored as a potential approach for early detection of micro-damages. The typical nonlinear phenomenon is the generation of second harmonics. Considering that second harmonics could provide information sensitive for structural health condition, this paper investigates an experimental scheme for characterizing thermal fatigue damage in composite laminates using second harmonic Lamb waves. Specimens were subjected to artificial thermal fatigue to simulate the effect of temperature variation of in-service aircraft composite structures. The present results show a monotonic increase of acoustic nonlinearity with respect to thermal fatigue cycles. The experimental observation of the correlation between the acoustic nonlinearity and thermal fatigue cycles in carbon/epoxy laminates verifies that nonlinear Lamb waves can be used to assess thermal fatigue damage rendering improved sensitivity over conventional linear feature based non-destructive evaluation techniques. Velocity and attenuation based ultrasonic studies are carried out for comparison with the nonlinear ultrasonic approach and it is found that nonlinear acoustic parameters are more promising indicators of thermal fatigue damage than linear ones.


Powered by OpenConf®
Copyright ©2002-2012 Zakon Group LLC