7XXX계 Al기지 복합재료의 인장 및 압축에 의한 변형 및 손상

Abstract

The hardening and damage in tensile and compressive deformation of 7XXX Al matrix composites were analyzed. The effect of the damage in the particles and/or at the interfaces on the stress-strain response is different in tension and in compression. In tension, cracks mostly perpendicular to the stress axis in ceramic particles definitely lower the loading capacity and then the overall hardening rate. With increasing tensile strain there may be cracking of additional particles and the localized strain developed at the tip of cracks and in the matrix linking the cracked particles. Therefore tensile deformation behavior of Al matrix composite is more strongly influenced by the size of reinforced ceramic particle than the matrix properties. On the other hand in compression cracks mostly parallel to the stress axis in ceramic particles are not expected to lower the loading capacity and have little influence on the hardening rate. The growth and the link-up of damage in compression are difficult because of the compressive stress near crack tips. Therefore, the flow stress is not greatly influenced by the frequency of particle cracks and it is strongly dependent on the matrix properties.