STUDY OF DELAMINATION IN COMPOSITES BY USING THE SERIAL/PARALLEL MIXING THEORY AND DAMAGE FORMULATION

X. MARTINEZ; S. OLLER; E. BARBERO

Porto

Conferencia; STUDY OF DELAMINATION IN COMPOSITES BY USING THE SERIAL/PARALLEL MIXING THEORY AND DAMAGE FORMULATION; 2007

The lost of adherence between the diferent layers of the composite leads to a reduction of the section strength and stiffness that can  finish in a structural failure.The importance of this phenomenon is demonstrated by the amount of authors that have developed theories and formulations to deal with it. All authors that have studied the problem agree that the delamination process is characterized by two main phenomenons, the crack initiation and its propagation along the composite. Crack initiation can be obtained by comparing the strain{stress state of the material, in the region where delamination takesplace, with a critical one [1, 2, 3, 4] or in terms of the traction versus relative displacement [5, 6, 7]. And the delamination propagation is usually treated opening the mesh to simulate the crack e®ect where it takes place. To open the mesh di®erent procedures are proposed. One of them is the virtual crack closure technique (VCCT) [8], based on the assumption that when a crack is extended, the energy required to open the crack is the same required toclose it. Another procedure, each time more used, is the use of a cohesive zone model [2]. The cohesion elements are placed in the interface of the layers that can su®er delamination and its propagation is obtained with damage or plastic formulations applied to those elements.