7 - Modelling damage in laminate composites

Abstract

Publisher Summary The failure of Glass- and Carbon-Fiber Reinforced Plastic [“GFRP” and “CFRP”] laminates subjected to static or cyclic tensile loading acting in the plane of reinforcement, and also under thermal fatigue, is a complex process. It involves sequential accumulation of various types of intra- and interlaminar damage, which gradually lead to the loss of the laminate's load-carrying capacity. The main damage mechanisms, exhibited in composite laminates, are matrix cracking, delamination, fiber debonding, and fiber breakage. Damage mechanisms in composite laminates can be studied theoretically following two approaches. Using the continuum damage mechanics approach, various types of damage are accounted for via the damage tensor. A composite is described as a continuum with mechanical properties depending on the damage tensor. Using the damage micromechanics approach, stress analysis of the damaged composite is carried out in the explicit presence of damage. Various types of damage are analyzed directly with the aim to predict their onset and growth, and also their effect on the properties of the laminate. While for homogeneous isotropic materials it is possible to obtain exact solutions within the linear elasticity theory, stress analysis of damaged composite laminates is approximate in the majority of cases. If interaction between various types of damage is especially complex, stress field can only be determined by numerical methods such as the finite-element method.