Modeling and finite element simulation of polypropylene behavior under severe plastic deformation by high-pressure torsion

Severe plastic deformation (SPD) technology is the most effective method for producing nanomaterials. Among the SPD processes, high-pressure torsion (HPT) stands out as a promising technique for generating substantial shear strain. It has attracted considerable attention as a novel processing method for nanostructured materials. This is primarily due to its unique ability to subject the material to infinitely large strains and to induce extensive plastic deformation without causing significant changes in the cross section of the sample. In this paper, a phenomenological elastic-viscoplastic constitutive model has been experimentally identified and coupled with the three-dimensional finite element method to investigate the different processing parameters governing the deformation behavior of polypropylene (PP) during the HPT process. The plastic deformation behavior of polypropylene (PP) resulting from the HPT process has been investigated. The effects of various HPT process parameters such as process sequences, compression displacement, torsion angle, angular velocity, and sample dimensions are presented and discussed. The results provide insight into the correlation between process parameters and the evolution of equivalent plastic strain, indicating that an increase in sample radius, compression displacement, and torsion angle leads to a higher equivalent plastic strain. A non-uniform distribution of equivalent plastic strain is observed, particularly in the radial direction, with higher values observed at the sample periphery.