Multiscale modelling of deformation and failure in thermoplastic polymers

The two groups submitting this application; Institute of Mechanics at Karlsruhe Institute of Technology (KIT), and SIMLab at Department of Structural Engineering at the Norwegian University of Science and Technology (NTNU), are both working on material mo dels for thermoplastics. The activity on polymers is relatively new at both groups, involving 1-2 faculty members and a couple of PhD students. The general aim at both groups is to come up with improved material models to be used in finite element simulat ions. They work, however, along slightly different axes. While SIMLab possesses a well-equipped laboratory, facilitating a wide spectre of mechanical tests, the group in Karlsruhe has to a greater extent put its attention to the micromechanical descriptio n of the material. Common for both groups is strong skills within the finite element method and in particular material modelling. Despite substantial research effort within numerical predictions of the repsonse of thermoplastics during the last decades, existing models for thermoplastics in commercial FE codes still need further improvements. A feature observed for important thermoplastics such as polypropylene (PP) and polyvinylchloride (PVC) is the formation of voids during deformation. This phenomenon is known as damage in solid mechanics, and has a great influence on the material's response during deformation as well as the onset of fracture. As a promising tool for the development of predictive macroscopic material models that accurately capture the effect of damage until ultimate failure under various loading conditions, we consider a combined approach which comprises experiments on the real material as well as multiscale mechanical models.