| The free edge delamination is one of the important damage reasons of thermoplastic composite laminates AS4/PEEK. To optimize the design of this material and evaluate its structure inactivation, it is the necessary to do quantitative analysis to the mechanical behavior of free edge delamination.Using three-dimensional orthotropic elastic finite element method, a fracture mechanics finite elemental model of tensile thermoplastic AS4/PEEK laminates with delamination crack in free edge is developed in this article ,in order to consider the r-1/2 singularity of the inter-laminar stress distribution at crack tip . For AS4/PEEK [0/90]s, [0/±45/90]2s and [±25]s4 laminate, the free edge inter-laminar stresses at tips of delamination cracks between different laminates of these composite materials are analyzed ,which includes the interactions between them under uniaxial tensile loading. The result shows that:The values of free edge interlaminar stresses apparently increase due to free edge delamination cracks,such as interlaminar normal stressesσy in [0/90]s, interlaminar normal stressesσy and shear stressesτxy between -45and90 layers in [0/±45/90]2s,and interlaminar shear stressesτxy in [±25]s4 laminated composites.Using three-ply microscopic submodeling FEM with two phases of fiber and matrix, the influences of the free edge delamination on the elastic-plastic stress fields in the geometrical interlaminar areas near fiber-matrix interface are preliminarily investigated. It is shown that the stresses on fiber-matrix interface are larger than homologus geometrical interlaminar stresses.
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