Effect of fiber cross section geometry on cyclic plastic behavior of continuous fiber reinforced aluminum matrix composites

This paper investigates the cyclic plastic behavior of continuous fiber-reinforced aluminum matrix composites (CFAMCs) with different shape of fiber cross section arranged in a square packing geometry. The 2D micromechanical FEM models, composed of elastic undamaged reinforcement perfectly bonded to an elastic-perfectly plastic matrix with a volume fraction equal to 30%, are subjected to off-axis constant macro stress and a cyclic temperature history. under such load conditions, the matrix undergoes large internal inelastic deformations potentially leading to internal crack initiation as well as macroscopic ratcheting. The computational method, the Linear Matching Method (LMM), is used throughout the analysis for the direct evaluation of shakedown, alternating plasticity and ratcheting behaviors. The effect of the matrix yield stress thermal degradation upon two common design limits, i.e., the reverse plasticity limit and the ratchet limit, is also investigated and discussed, including its influence on the off-axis low cycle fatigue crack initiation.