Global/Local Approach using Partial Hybrid Finite Element Analysis of Stress Fields in Laminated Composites with Mid-Plane Delamination under Bending

A global/local approach using partial hybrid elements is presented to study the interlaminar stress distribution around delamination crack tips in composite laminates subjected to out-of-plane loading. The cracked composite laminate is modeled with three types of elements. 20-node three-dimensional sublaminate partial hybrid elements are used in the local region where the stress gradients are expected to be sharp, 8-node degenerated partial hybrid plate elements are used in the global region and 15-node transition elements are employed to connect the local and global regions. The results show that the global/local approach yields accurate solutions with much less active degrees of freedom, less consumption of computer space and CPU time as compared with the conventional displacement element. Experiments are performed for cross-ply laminates with midplane delamination crack subjected to three-point bending. The predicted critical loads by finite element analysis based on both a strength-based criterion and a fracture mechanics approach are in good agreement with the experimental data.