Oscar S. Wyatt, Jr. Endowed Chair, Texas A&M University, College Station, TX
Graduate research assistant, Virginia Polytechnic Institute & State University, Blacksburg, VA
A three-dimensional (3-D) progressive failure algorithm is developed where the Layerwise Laminate Theory of Reddy  is used for kinematic description. The finite element model based on the layerwise theory predicts both inplane and interlaminar stresses with the same accuracy as that of a conventional 3-D finite element model. Besides, it provides a convenient format for modeling the 3-D stress fields in composite laminates . The progressive failure algorithm is based on the assumption that the material behaves like a stable progressively fracturing solid. The stiffness reduction is carried out at the reduced integration gauss points of the finite element mesh depending on the mode of failure. A parametric study is conducted to investigate the effect of out-of-plane material properties, 3-D stiffness reduction methods, and boundary conditions on the failure loads and strains of a composite laminate under axial extension. The results indicate that different parameters have a different degree of influence on the failure loads and strains. Finally, the predictive ability of various phenomenological failure criteria is evaluated in the light of experimental results available in the literature, and the predictions of the Layerwise Laminate Theory (LWLT) are compared with those of the First-Order Shear Deformation Theory (FSDT). The study concludes that a 3-D stress analysis is necessary to predict accurately the failure behavior of composite laminates.
Paper ID: CTR10358J