Multi-sensor techniques to study fatigue damage progression in structural materials

Fatigue failure is catastrophic once the material reaches the critical damage, but the damage accumulation is, in general, gradual. Several methods are used to study the fatigue damage progression, such as: microstructural investigation, stiffness degradation measurements, and loss of ductility etc. to predict the remaining life of dynamically loaded components. Non-destructive test methods such as ultrasonic, eddy current and infrared thermography are the other techniques that are used to sense the change in material response due to fatigue loading. This paper presents a glimpse of results to understand the fatigue damage progression in structural materials; infrared thermography is used to understand fatigue damage in copper, while X-ray computed tomography is used to study damage progression in an impact damaged carbon fiber reinforced plastic laminate. The damage volume is measured based on CT images and correlated with stiffness drop. Based on the study, it was observed that the use of multiple sensors and measurement techniques in tandem with other conventional experimental methods provides an insight into damage progression.