Effective stress during biaxial compression of powder aggregates

An equation to calculate the effective stress acting on interparticle contacts during the biaxial compression of a powder aggregate is proposed. This equation is obtained by a new method in which the study of the stress–strain relationship is not necessary. This new method does not require the use of sophisticated numerical computation software. The proposed expression satisfies upper and lower boundary conditions, and its range of application is greater than that of other equations, which are often limited to very small deformations. In this work, initially, simple cubic packing of spheres is studied, and then results are extrapolated to real powder systems using a normalised porosity. The proposed equation can be useful in compaction and extrusion processes.