TSG Mikro Sim – Multi-scale foam simulation

Microscale model for multiscale simulation of thermoplastic foam injection moulding

Physically foamed thermoplastic injection moulded components have many advantages over compact parts. However, precise technical design using structural simulation is not possible, as effects such as cell deformation due to shear effects, coalescence and bubble collapse are not taken into account. This is where the DFG project comes in, investigating how these effects can be modelled and calculated using a micro-simulation of foaming in the injection moulding process.

© IKV

As a basis for a micro-scale foaming model, mathematical and physical descriptions for nucleation and bubble growth were researched and adapted for injection moulding. Multiphase flow simulation for compressible media was developed in the open-source software OpenFOAM. In addition to shear viscosity, strain viscosity is relevant for modelling bubble growth, which is why a Phan-Thien-Thanner model was used and fitted to describe viscoelasticity in comparison to conventional purely viscous models.

The microsimulations show real deformation phenomena caused by shear and interactions between bubbles as influencing factors on the final cell geometry and coalescence (Fig. 1). The distribution of bubble size, orientation and aspect ratio can also be interpolated for other positions by selecting suitable support points.

Project data and funding

We would like to thank the DFG for funding the project (funding reference HO 4776/81-1) and the project partners for their cooperation.

Project duration: 01.09.2022 – 31.01.2026