Damage initiation and propagation in laminated composites under static andrnfatigue is addressed by using the Discrete Damage Modeling (DDM) method. Thernessence of this technique is the insertion of true displacement discontinuitiesrnindependent of mesh orientation to simulate matrix cracking. Multiple cracking inrneach ply is allowed. All plies are tied together by using cohesive interfaces, which arernallowed to delaminate. Matrix cracks in two adjacent plies interact through therninterface cohesive model and their presence is a major delamination initiator. Therncomputation begins without any matrix cracks present. After each loading incrementrnfailure criterion is evaluated for matrix failure mode, and if exceeded, then a matrixrncrack is inserted. In the next increment, this crack begins to open by using cohesivernformulation. Failure criterion and cohesive zone model for initiation and propagationrnof cracking and delamination under fatigue loading was proposed. Examples forrnmethod demonstration and validation are presented.
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