Damage Analysis of Composite Laminates

The favorable mechanical properties of Composite materials are excellent stiffness/weight and strength/weight ratios, easy formability and corrosion resistance. The application of composites in structural components is still limited by the difficulty in predicting their service lives. The objective of this research paper is to develop and evaluate damage initiation or delamination onset and growth in a C-C composite 8 layered pre-preg material 3D laminate model (dimension 25x3.4x85mm and ply thickness 1mm) under loading conditions without crack using ANSYS Autodyne tool subjected to a uni-axial load of 40N at the free end. Mapped quadrilaterals mesh is generated with 2610 nodes and 1792 elements. Cohesive Zone Model (CZM) formulations are more powerful than Fracture Mechanics approaches because they allow the prediction of both initiation and crack propagation. The composite laminate plate is thus bent due to Poisson effect, and crack opens up due to the heavy normal stress at the crack interface and the strain energy variation is uniform in length direction for pre-preg model. The bonding ply is affected heavily due to the load applied in the free end in upward and downward directions, resulting in delamination from crack propagation. The focus area is on delamination, one of the most common types of damage in laminated fibre reinforced composites due to their relatively weak interlaminar strengths. The total deformation, displacement, normal stress, strain energy and delamination resistance are analyzed to predict the life of the composite laminate. Finding the impact of variables contributing to the fracture of composite laminates, understanding the failure propagation, visualizing the modes of failure in the static structural analysis and comparing with the physical structural analysis results is the key take away. Expected outcome is to eliminate or considerably reduce one or more drawback(s) associated with damage prediction of composite laminates.