Progressive Failure Analysis Of Notched Fiber-reinforced Composite Laminates

Due to their advantages such as high specific modulus and high specific strength, advanced fiber reinforced composite materials are being widely used in fields like aerospace, weapons and marine, etc. The structural application of composite materials often requires the presence of holes or cut-outs. The behavior of composite materials with stress concentrations due to these notches is of great interest to designers because the damage growth around these stress concentrations will result in strength or life reduction of composite structures. In addition, the material heterogeneity and anisotropy make the situation more complicated. Therefore, it’s of great importance to investigate the failure of notched composite laminates.In most of the numerical models, fiber-reinforced composites are modeled as homogeneous anisotropic plates and no special treatments are taken for the stress concentration at the notch tips. Such models cannot describe the stress states in the composites accurately. This article presents a detailed analysis on the stress concentration in notched fiber-reinforced composites. Due to the formation of longitudinal splitting at notch tips along the fiber direction, the extremely high stress concentrations ahead of the notch tips could be drastically reduced for composites under remote tension. In this article a progressive damage model implemented in finite element software ABAQUS was created in order to better understand the failure mechanisms of notched composite laminates. To capture the true stress concentration at the notch tip, in-ply surface-based cohesive contacts along the fiber direction were introduced in the finite element model to simulate the splitting. To model the delamination, interface cohesive contacts were introduced between plies. Notched composite laminates with various layups and in-plane scaled sizes are investigated. Failure modes and failure loads obtained from finite element analyses were compared with experimental results from open literature to confirm the failure mechanisms of composite laminates.