TITLE:
Effect of Reinforcement Clustering on Crack Initiation Mechanism in a Cast Hybrid Metal Matrix Composite during Low Cycle Fatigue
AUTHORS:
A. K. M. Asif Iqbal, Yoshio Arai, Wakako Araki
KEYWORDS:
Cast Metal Matrix Composites; Crack Initiation; Reinforcement Clustering; Low Cycle Fatigue
JOURNAL NAME:
Open Journal of Composite Materials,
Vol.3 No.4,
September
12,
2013
ABSTRACT: The
reinforcement distribution of metal matrix composites (MMCs) plays an important
role in low cycle fatigue. Thus, it is essential to study the effect of
reinforcement clustering on the crack initiation mechanism of MMCs. In this
study, the effect of reinforcement clustering on the microcrack initiation
mechanism in a cast hybrid MMC reinforced with SiC particles and Al2O3 whiskers was investigated experimentally and numerically. Experimental results
showed that microcracks always initiated in the particle-matrix interface, located in the
cluster of the reinforcements. The interface debonding occurred in the fracture
which created additional secondary microcracks due to continued fatigue
cycling. The microcrack coalesced with other nearby microcracks caused the
final fracture. To validate the experimental results on the microcrack
initiation, three dimensional unit cell models using finite element method
(FEM) were developed. The stress distribution in both the reinforcement
clustering and non-clustering regions was analyzed. The numerical analysis
showed that high stresses were developed on the reinforcements located in the
clustering region and stress concentration occurred on the particle-matrix interface. The high volume
fraction reinforced hybrid clustering region experienced greater stresses than
that of the SiC particulate reinforced clustering region and low volume
fraction reinforced hybrid clustering region. Besides, the stresses developed
on the non-clustering region with particle-whisker series orientation were
reasonably higher than that of the non-clustering region with particle-whisker parallel orientation. The high
volume fraction reinforced hybrid clustering region is found to be highly
vulnerable to initiate crack in cast hybrid MMC during low cycle fatigue.