Failure analysis of notched fiber-reinforced composite materials

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. 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 tip. Such models cannot describe the stress states in the composites accurately. This article presents a detailed analysis on 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. An efficient finite element model is created in this article 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 contact along fiber direction were introduced in the finite element model to simulate the splitting. To modeling the delamination, interface cohesive contacts were introduced between plies. Failure modes and failure loads obtained from finite element analyses were compared with experimental results to confirm the failure mechanisms of composite laminates.