Damage and Performance Characterization of ARALL Laminates Subjected to Tensile Cyclic Loading
SourceThe behavior of ARALL (ARamid ALuminum Laminates) subjected to tension-tension cyclic loading was experimentally investigated as a first step towards the understanding of the long-term behavior of ARALL laminates. Specifically, this work addresses fatigue damage mechanisms and relationships between damage and stiffness change, remaining strength, and life. The quasi-static and dynamic material response of unnotched ARALL-2 coupons were measured at normalized maximum stress levels (5) ranging from 0.4 to 0.9 of the ultimate tensile strength. The damage mechanisms and failure modes changed over this range of cyclic stresses. while at low cyclic stress levels, the fatigue properties of the fiber-reinforced plies are key factors; at high cyclic stress levels, the laminate's response is governed by the aluminum plies. Five distinct stages were recognized in the damage sequence. A shear lag analysis is presented to model the regular spacing of cracks called the characteristic damage state. Appropriate modifications were made to accommodate for the hybrid nature of the laminate.