Simulation of Delamination Composite Materials

AbstractThe use of decohesion elements for the simulation of delamination in composite materialsis reviewed. The test methods available to measure the interfacial fracture toughnessused in the formulation of decohesion elements are described initially. After a briefpresentation of the virtual crack closure technique, the technique most widely used tosimulate delamination growth, the formulation of interfacial decohesion elements isdescribed. Problems related with decohesion element constitutive equations, mixed-modecrack growth, element numerical integration and solution procedures are discussed.Based on these investigations, it is concluded that the use of interfacial decohesionelements is a promising technique that avoids the need for a pre-existing crack and pre-defined crack paths, and that these elements can be used to simulate both delaminationonset and growth. Introduction The fracture process of high performance composite laminates is quite complex, involving bothintralaminar damage mechanisms (e.g. matrix cracking, fiber fracture) and interlaminar damage(delamination). An example of a failure with interactive modes is illustrated in Figure 1. Although someprogress has been made lately in the development of accurate analytical tools for the prediction ofintralaminar damage growth, similar tools for delamination are still not available, and thus delamination isgenerally not considered in damage growth analyses. Without the delamination failure mode, thepredictive capabilities of progressive failure analyses will remain limited.Figure 1. Interaction between intralaminar and interlaminar damage mechanisms [1].