Fatigue damage of metal matrix composite laminates - Bimodal theory and damage optimization

A damage-induced shakedown state is identified, and the low-cycle crack-growth process associated with the cyclic plastic straining of the matrix is regarded as a shakedown mechanism in metal matrix composites (MMC). A model of the shakedown process is formulated as a nonlinear optimization problem. The total damage in the laminate is considered to be the objective function minimized under nonlinear constraints which are derived from the requirement that the prescribed loading program is contained within the yield surface of the damaged composite.