MODELING OF DAMAGE IN AN MMC WITH LAMELLAR MICROSTRUCTURE

摘要

Metal-ceramic composites offer many advantages over monolithic metals and their alloys such as high specific stiffness and strength, belter creep, fatigue and wear resistance, and good thermal properties. One of the recent advances in this area has been made possible thanks to innovative ceramic preforms, fabricated by freezing a water-alumina suspension and subsequent freeze-drying and sintering. As a result these metal/ceramic composites possess a hierarchical lamellar microstructure, with randomly orientated individual regions (domains), in which all ceramic and metallic lamellae are parallel to each other. Metal-ceramic composites with hierarchical lamellar microstructure exhibit pronounced elastic and plastic anisotropy at the domain level. In this paper, stress fields in a single-domain sample of metal-ceramic composite containing multiple cracks in the ceramic layer are investigated. The cracked microstructure for different stage of damage is modeled by analytical and computational approaches. The stress field is determined using a modified 2-D shear lag approach and a finite element method. The result obtained by finite elements analysis is consistent with experimental results. According to the obtained result, the average axial stress between two cracks is decreasing with decreasing the distance between the cracks.