Analysis of Specific Pressure Necessary to Extrude Aluminium Alloy Compacts

Abstract

The mechanical properties of aluminium alloy powder compacts vary throughout the quasi-static deformation zone. Experimental evidence has suggested that the flow stress is dependent upon both strain and strain rate such that an equation of the form δ = Aε^mε ⁿ best describes material behaviour under deformation conditions. This paper presents a mathematical analysis of the deformation by modifying an axi-symmetric upper-bound solution and utilizing a penalty function approach to minimization to obtain the stress constants. It is shown that for a cast billet this approach predicts the specific pressure accurately and that for powder compacts the constants k, m, and n may be obtained and a satisfactory prediction of pressure facilitated.