Mathematical model and algorithm for calculating pressing and sintering

On the basis of the thermodynamic approach, the constitutive relations for processes of pressing and sintering of powder composites have been obtained. A kinetic equation is been added to the system of equations of the usual theory of elastoplasticity to calculate the evolution of porosity under non-thermomechanical action by a bulk compressive stress of sintering. The modified theory is included in the computer program for calculating elastoplastic media for adaptation to sintering processes. Numerical calculations demonstrate the ability of the modified theory of elastic-plasticity to simulate the main effects of pressing and sintering, including the calculation of residual porosity, stresses and deformations in the compact, as well as its residual shape. Also on the basis of the proposed theory, the problem of "hot" sintering under the action of a mobile high-energy pulse ("laser sintering") is numerically solved. The influence of the parameters of the laser action on the sintering of powder material, as well as on the distribution of porosity and temperature, is calculated.