Numerical constitutive laws for powder compaction using particle properties and packing arrangement

Numerical studies, calibrated and validated using experiments, were carried out to develop a constitutive law for powder compaction. In order to simulate powder compaction at particle level, single particle compression/breakage test is used to characterise the mechanical properties, which include elastic modulus, Poisson’s ratio and yield strength. Finite Element Analysis (FEA) of single particle compression was carried out and validated vs. single particle compression testing and then used to establish a suitable hardening law. The particle size, shape and packing arrangement were obtained using X-ray computed tomography. This information was transferred to FEA. Due to the presence of complex geometrical structures, Meshlab and Solidworks were chosen to deal with the arrangement of particles in the structure. The multi-particle finite element method (MPFEM) was implemented into the finite element software package Abaqus/EXPLCIT v6.14 and used to simulate the powder compaction process. The model input parameters include mechanical properties (of the single particle) and interactions between particles (e.g. friction). The stress-strain curves predicted by MPFEM were validated experimentally using compaction tests performed in a die instrumented with radial stress sensors. The method proposed was used for constitutive model development for powder compaction as an alternative to bulk powder characterisation. The stress-strain curves MPFEM were analysed using the deformation plasticity framework. Contours of constant complementary work in Kirchhoff stress space were established and a model consistent with the behaviour of the materials was identified in order to capture the materials response under conditions experienced in practical die compaction processes.