Thermal residual stress analyses of Nextel 440/aluminum composite

Finite element analyses were performed to evaluate the residual stresses de veloped during the fabrication process of the Nextel 440/A1-6061 composite. The purpose of the analyses was to find the effect of fiber orientation an d fiber spacing on processing-induced thermal residual stresses in the meta l matrix composite with noncircular fibers' cross section. It was found tha t high compressive stresses developed between two fibers that increased as the two fibers approached each other. However, significant tensile stresses developed between fibers once the two fibers touched each other. The trans ition from compression to tension is explained by considering the force bal ance between contacting fibers. The normal stress on the fiber/matrix inter face was higher when the major axis of two noncircular fibers' cross sectio n was oriented at 45 degrees to each other, than it was when the major axis was oriented at 0 degrees to each other. The normal residual stress at the fiber/matrix interface for noncircular fiber geometry was higher compared to what would have developed using round fibers.