A Kamaloo - MSc student, Department of Mechanical Engineering, Faculty of Engineering , Islamic Azad University, Karaj Branch, Karaj, Iran
R Madoliat - Associate Professor, Department of Mechanical Engineering, Iran University of Science and Technology, Tehran ۱۶۸۴۶-۱۳۱۱۴, Iran
A Ghasemi-Ghalebahman - Assistant Professor, Department of Mechanical Engineering, Semnan University, Semnan ۳۵۱۳۱-۱۹۱۱۱, Iran

An elitist non-dominated sorting genetic algorithm (NSGA-II) is used to optimize the local delamination growing from transverse matrix cracking in laminated composites subjected to in-plane biaxial fatigue loading. The objectives of this research are minimization of weight and delamination fatigue crack growth rate (DFCGR) simultaneously to achieve a damage tolerant structure with most delamination resistance and lightest weight among all possible choices. The fiber orientation, fiber volume fraction, ply thickness, and staking sequence are chosen as the design variables. To define the problem statement, we consider symmetric laminates which one of their layers contains a single matrix crack that induces local delamination at the ply interface. The DFCGR is characterized using a Paris law based on the energy release rate associated with local delamination growth. Utilizing 2D shear-lag method, the stiffness degradation is evaluated by employing the equivalent constraint model (ECM) of the damaged lamina. The application of the approach is demonstrated for glass/epoxy and carbon/epoxy laminates to verify the effectiveness of the proposed method.

Non-dominated sorting genetic algorithm (NSGA-II), equivalent constraint model (ECM), composite laminate, delamination fatigue crack growth, 2D shear lag