Application of computed tomography data–based modelling technique for polymeric low density foams, Part B: Characterization of the mechanical behaviour

The non-linear material behaviour of low density polypropylene foams is investigated under several quasi-static loading conditions with a combined modelling technique based on computed tomography data and Voronoi diagrams. A simulation methodology for determining the linear elastic properties is introduced in Hössinger-Kalteis et al. (2021). In this paper, the methodology is extended regarding the material model, where additionally the non-linear region is considered. The model takes into account property determining microstructural features like orientation-dependent cell wall thicknesses and anisotropic cell shapes. Thus, the anisotropic material behaviour under tension and compression load is estimated for extrusion foams with different densities utilizing the microstructural simulation model. Based on the characterized behaviour under tension and compression, constitutive models are generated. These are implemented in bending test simulations due to lower computational effort. The simulation results are validated with experimental results, which shows that the model gives satisfactory results.

Development and investigation of the applicability of computed tomography data-based modelling technique for polymeric high-density foams

As foams have become very important in several areas and since characterizing their properties is a crucial task, a finite element simulation model for high-density closed cell foams based on computed tomography (CT) measurements is developed. The model includes realistic microstructural features like cell size distribution due to the utilization of CT data. Moreover, a ‘skin-core-skin’ microstructure resulting from the manufacturing process (injection moulding) of the foams is also considered in the model. The mechanical behaviour of the foam’s core layer under tension and compression load is characterized based on the microstructural model to develop constitutive material models of the foam. These constitutive models enable further mechanical characterization of the foam with less computational effort. Compression and bending test simulations of injection moulded foams with three different densities are validated with corresponding experimental results. Thus, conclusions can be drawn regarding the reliability, applicability and possible further extensions of the high-density foam model.