Evaluation of residual strength of notched fiber metal laminates

Fiber metal laminates (FML) are a family of hybrid materials consisting of alternating layers of thin metal sheets and fiber-reinforced epoxy prepregs. In contrast to aluminum alloys, the presence of notches in FML causes significant strength reductions. The objective of this study was to evaluate the residual strength of fiber-reinforced metal laminates with a circular open hole. Mechanical testing was performed to determine the unnotched tensile properties and notched strength of bi-directionally reinforced fiber metal laminates. The influence of specimen dimension and notch size on residual strength and notch sensitivity of fiber metal laminates was investigated. A modified point stress criterion was introduced to predict the residual strength of fiber metal laminates with open hole. An excellent agreement between experimental results and model prediction was obtained. The residual strength predicted from this modified model also correlated very well with the experimental data in the literature for various other types of fiber metal laminates. A computer simulation based on finite element method was performed to study stress concentration and stress concentration around notch. Failure modes, damage initiation and progression of notched fiber metal laminates are also characterized and discussed.