Finite element analysis of free corner effects in composite laminates based on a global-local model

In this paper, the effect of free corner in angle-ply and cross-ply symmetric composite laminates on the interlaminar stresses is studied based on a global-local model using the finite element method. To do this, the global region is analyzed by the first-order shear deformation theory, and the local region is modelled by the layer-wise theory. The laminates are exposed under uniform mechanical extensional loading and thermal loading, and the effects of several factors, including the orientation of ply fiber and the thickness, layout, stacking, and number of plies, are examined on the interlaminar stresses at the vicinity of free corner. The presented results are compared with available literature which demonstrates good agreement. The results reveal that an increase in the layer thickness leads to a decrease in the interlaminar stresses connoting that the interlaminar stresses can be neglected in sufficiently thick laminates. For example, the normal and shear interlaminar stress is evaluated as 16.3 and 2.32 MPa for the ply thickness of 0.1 mm, respectively, while they decrease to 0.85 and 0.23 MPa for 1.5 mm thickness. It is also found that a change in the number of layers of laminate does not significantly affect the interlaminar stresses. Furthermore, the results show that, in angle-ply laminates, the corner effect is highlighted. The results of this study are useful in the optimal design of composite laminate against damage mechanisms such as delamination and matrix cracking.