  Residual stress and plastic strain in additive manufactured materials can
exhibit significant microscopic variation at the powder scale, profoundly
influencing the overall properties of printed components. This variation
depends on processing parameters and stems from multiple factors, including
differences in powder bed morphology, non-uniform thermo-structural profiles,
and inter-layer fusion. In this research, we propose a powder-resolved
multilayer multiphysics simulation scheme tailored for porous materials through
the process of selective laser sintering. This approach seamlessly integrates
finite element method (FEM)-based non-isothermal phase-field simulation with
thermo-elasto-plastic simulation, incorporating temperature- and
phase-dependent material properties. The outcome of this investigation includes
a detailed depiction of the mesoscopic evolution of stress and plastic strain
within a transient thermo-microstructure, evaluated across a spectrum of beam
power and scan speed parameters. Simulation results further reveal the
underlying mechanisms. For instance, stress concentration primarily occurs at
the necking region of partially melted particles and the junctions between
different layers, resulting in the accumulation of plastic strain and residual
stress, ultimately leading to structural distortion in the materials. Based on
the simulation data, phenomenological relation regarding porosity/densification
control by the beam energy input was examined along with the comparison to
experimental results. Regression models were also proposed to describe the
dependency of the residual stress and the plastic strain on the beam energy
input.
