MICRO-DAMAGE MODEL OF COMPOSITE MATERIALS WITH PARTICLE AND DEFECT INTERACTION

Stress concentration is much bigger around the sharp angle of the non-ellipsoidal particle than around the ellipsoidal particle, and the cracks beside the particles caused by the stress are the primary damage of composite ceramics. Particle caused crack usually extends to the composite matrix to form the penny crack when the particle is stiffer than the matrix and the interface is strong. Considering the crack propagation was controlled by the stress around the particle, the meso-damage mechanical model is obtained based on the effective self-consistent theory, to describe the damage evolution of the composite ceramic under simple tension. The influences of particle shape, sizeand stiffness, and the distance between the crack and the particle on the composite damage are analyzed. The result indicated that the nonellipsoidal particle is more easily to cause crack propagating than the similar ellipsoidal particle, and the damage degree is much higher in the composite with non-ellipsoidal particle than with non-ellipsoidal particle under the same loading. Composite strength with non-ellipsoidal particle is smaller than that with ellipsoidal particle. Stable damage process is more obvious in composite with flat particle and the strength is much higher. Increasing the particle stiffness and the particle volume fraction can improve the composite strength. The stable damage is unobvious in composite when the primary defect size is too large or too small.