A New Constitutive Model for Alumina Powder Compaction

Abstract

Based on a systematic experimental investigation of the mechanical properties of alumina powder a new general 3-D constitutive model for compaction of powders has been developed. A significant feature of the model is that it describes the time effects on compaction. These effects have been revealed by creep and relaxation phenomena and by the influence of the strain rate. Although the theory is applicable to general 3-D conditions all the parameters involved in the model can be derived from the results of a few number of conventional triaxial drained compression tests. The procedure to identify the model parameters from data is general. Unlike the models available in the literature, the model developed in the present paper accounts for both compressibility and dilatant behavior of powders. Thus it provides a realistic description and a better understanding of the mechanisms of powder pressing. The theory is able to model important aspects of powder behavior with a degree of accuracy which appears to make it useful in FEM analyses of stress and density distribution in a pressed compact.