Capability of Determining Fatigue Mechanisms in 7075 Aluminum by Combining Ultrasonic Attenuation and Acoustic Emission Monitoring

Despite the prevalence of fatigue and fatigue related failures little is known about the actual mechanisms which cause fatigue. Two nondestructive investigation techniques which have been found to be extremely sensitive to the microscopic changes in the material during fatigue deformation are ultrasonic attenuation and acoustic emission monitoring. The work reported here indicates the ability of both techniques to provide an early warning of fatigue failure in 7075 aluminum. Additionally, the results point out the sensitivity of the techniques to different mechanisms active during fatigue deformation. Through the complementary use of solitary and combined monitoring the potential of these techniques for revealing the actual mechanisms responsible for fatigue is shown