Fracture behavior of roll bonded Al-brass-Al multilayer composites – Concept of the maximum undamaged defect size (dmax)

Abstract

Multilayer sandwich composites consisting of two skin metals and perforated interlayer are rapidly becoming a good substitute for metal structures, especially in the automobile industry. Their good mechanical properties including excellent fatigue and impact strength, as well as damage tolerance, are accomplished. In this study, aluminum-perforated brass-aluminum sandwich composites are fabricated using roll bonding technique. Samples were made at different surface roughness, and their bonding behavior is investigated using peel test. The fracture behavior under mode-I was investigated. The effect of surface roughness (two different sand paper grits 50 and 80) on the fracture energy of mode-I peeling failure is studied experimentally. It is found that, the peeling resistance increased with increasing the surface roughness. To simulate the progressive failure of this sandwich composite, 3-D finite element model is employed in the present work. Virtual-Crack-Closing-Technique (VCCT) debonding model has been adopted to predicate the peeling failure. The concept of the maximum size of undamaged defect (dmax) has been adopted to predict the effect surface roughness on peeling load numerically. The numerical and experimental results showed an agreement between them. Therefore, the present 3D finite element model can be considered as a good candidate to expect the peeling damage in sandwich composites.