A densification and flow stress evolution constitutive model for powder-based discontinuously reinforced aluminum

Discontinuously Reinforced Aluminum (DRA) composites are a class of material that has generated much interest in the technical community due to its combination of outstanding mechanical properties and lighter weight with respect to steel. The relatively high processing costs of DRA material however, has restricted its widespread use in many automotive and aerospace applications. The development of a densification and flow stress evolution constitutive model for a DRA composite material is presented. A porous yield criterion based on the Gurson micromechanical model, as modified by Tvergaard, Richmond and Smelser, and Wang is used to predict the densification response of the powder processed composite material. The evolution of flow stress during axisymmetric compression testing has been modeled using the hyperbolic sine law and single internal state variable theory. The importance of microstructural evolution mechanisms such as precipitation, recrystallization, creep driven recovery, and deformation driven heating on the deformation of a 2xxx aluminum alloy and a 2xxx/SiC/20p DRA composites is discussed. The material constitutive model has then been imbedded in the ABAQUS finite element method package to allow realistic deformation processing simulations of a powder preform composed of the modeled DRA composite material.