Optimal weaving for 2.5D interlocks

This paper deals with optimizing the representative volume element (RVE) of 2.5D interlock composites for enhanced damage resistance and elastic stiffness. The elastic moduli of the composite are determined as a volume average of the moduli of the matrix and fiber, while the overall resistance to failure is obtained through incremental use of the 3D Tsai-Wu failure criterion. The variables considered for the optimization problem are the volume fractions of the fibers, their proportions in each direction and the weaving step of the vertical reinforcement. The optimization is carried out using a sequential quadratic programming approach (SQP) and the results are validated against experimental data obtained for 2.5D interlocks with carbon reinforcements.