From the summary: We provide a constitutive model for overall (macroscopic) plastic deformation behavior in a rubber-toughened polymer blend. A porous plasticity theory is employed as a basis for the constitutive modeling. In our investigation, the polycarbonate (PC) is chosen as a matrix material of polymer blend. First, the true uniaxial stress-strain relation for PC, which is an important part of the constitutive model, is measured. Secondly, finite element analyses of neck propagation in a tensile specimen of PC are performed to test the efficiency of the introduction of accurately measured true stress-strain relation into the model. Then, in order to investigate local and average deformation behavior of the matrix material PC around cavitated rubber particles in polymer blend, an axisymmetric unit cell analysis is carried out. Finally, finite element analyses of the neck propagation in a tensile specimen of a rubber-toughened PC are performed, and numerical results are compared to experimental results.