Abstract:
A mathematical model of material microstructure formation in the
process of selective laser sintering was proposed. The model is
based on the stress and strain analysis in a representative volume
of a powder that contains some particles. The strains and stresses
are caused by contact interaction of particles due to surface
tension. It was assumed that the particles are made of elastoplastic
material. The material properties were described by the associative
Drucker–Prager model with hardening. The nonlinear effects caused
by large strains were taken into account. The model permits one to
determine the shape of particles in the deformed state and the shape
of pores. The numerical results were presented for the problem of
contact interaction between two particles that assume the spherical
shape before deformation. The displacements of centers of powder
particles were specified as input. The finite-element method was
used for computations. The flow rule was integrated using the
implicit Euler backward method. The mortar method was used to solve
the problem with account of contact interaction. The distribution of
contact stresses over the surfaces of powder particles and
the distribution of the von Mises plastic strains in the section of
these particles were shown as a result of the analysis. The
dependence of contact zone radius on the contact displacements of
the particles' centers was investigated. It was analyzed how the
radius of contact zone depends on the material parameter
characterizing the pressure dependence of plastic flow.
Keywords:selective laser sintering, microstructure formation, large strains, plasticity, finite-element method.