3-DIMENSIONAL FINITE-ELEMENT PROGRESSIVE FAILURE ANALYSIS OF COMPOSITE LAMINATES UNDER AXIAL EXTENSION

A three-dimensional (3-D) progressive failure algorithm is developed w here the Layerwise Laminate Theory of Reddy [1] is used for kinematic description. The finite element model based on the layerwise theory pr edicts both inplane and interlaminar stresses with the same accuracy a s that of a conventional 3-D finite element model. Besides, it provide s a convenient format for modeling the 3-D stress fields in composite laminates [2]. The progressive failure algorithm is based on the assum ption that the material behaves like a stable progressively fracturing solid. The stiffness reduction is carried out at the reduced integrat ion gauss points of the finite element mesh depending on the mode of f ailure. A parametric study is conducted to investigate the effect of o ut-of-plane material properties, 3-D stiffness reduction methods, and boundary conditions on the failure loads and strains of a composite la minate under axial extension. The results indicate that different para meters have a different degree of influence on the failure loads and s trains. Finally, the predictive ability of various phenomenological fa ilure criteria is evaluated in the light of experimental results avail able in the literature, and the predictions of the Layerwise Laminate Theory (LWLT) are compared with those of the First-Order Shear Deforma tion Theory (FSDT). The study concludes that a 3-D stress analysis is necessary to predict accurately the failure behavior of composite lami nates.