Lecturer, Bristol University, Bristol,
Finite element micromechanical modelling of unidirectional silicon carbide/6061 aluminum has been conducted to investigate ways to improve the transverse tensile strain to failure. The analysis included the effects of nonlinear matrix behavior, interface debonding, residual stresses as a result of manufacturing, and subsequent stress relaxation. The influence of heat treatment, fiberpacking geometry, and volume fraction have been analyzed. The most important factor affecting transverse tensile ductility is the relationship between the stress at which the matrix yields and the interface strength. Residual stresses are beneficial because they are compressive in the radial direction at the interface, effectively increasing the interface strength. Highest ductility is obtained when significant plasticity occurs before interface debonding. The model suggests that this can be achieved by annealing the composite and arranging the fibers to be in thin plies, spaced apart as far as possible to reduce the stress concentration factor at the interface. Reducing the volume fraction is also beneficial provided it is done by increasing the fiber spacing rather than increasing the ply thickness.
Paper ID: CTR10084J