Development of a homogenisation approach to describe the mechanical behaviour of thermoplastic vulcanisates under consideration of the process-induced anisotropy
Mechanical Properties of Metallic Materials and their Microstructural Origins
Final Report Abstract
Due to regulatory measures that prescribe the increased use of recyclable materials and their recovery, there is increasing interest in replacing elastomers with thermoplastic elastomers (TPE). Thermoplastic vulcanisates (TPVs) are a sub-class of TPEs consisting of a thermoplastic matrix and chemically cross-linked elastomeric inclusions. Due to their multiphase structure, TPVs have the outstanding rubber-elastic properties of elastomers combined with the efficient processability and recyclability of a thermoplastic material. As a result, an increasing amount of elastomer components are replaced with TPV. When designing structural components made of TPV, new challenges arise, such as the process-induced anisotropy of the material. The anisotropy results from a geometric distortion of the elastomer particles in the TPV due to the high shear rates in the injection moulding process. Similar to short fibre reinforced plastics, a three layer configuration is formed. The resulting preferential direction results in a stiffness difference of up to 50 % in dependence of the extraction direction. To analyse the correlation between the distortion degree and the mechanical material response, the project used micromechanical models in the form of representative volume elements (RVE), which can represent the geometric configuration of the material. First, simple unit cell geometries and subsequently statistical RVEs were generated and analysed. To generate these structures, an algorithm was developed that can create RVEs with a sufficiently high elastomer content and high degrees of distortion. In addition, an efficient calibration approach was developed to determine material parameters for the individual phases from macroscopic tests independently of the degree of distortion. Parameter studies were carried out to determine findings for an analytical, anisotropic material model for efficient modelling of TPV. Finally, an analytical material model was developed that takes into account the influence of the production-related phase morphology and can map the resulting mechanical anisotropy based on a molecular statistical homogenisation approach. The developed model can be used in the long term to calculate the component behaviour of TPV structural components taking into account the production-related anisotropy in an integrative simulation chain. Until now, the prediction of the local particle distortion state in an injection moulding simulation is not possible.
Publications
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Micromechanical modelling of TPV. Nürnberg. DKT IRC 2021, Poster, 01. – 04.07.2021
Mentges, N. & Hopmann, C.
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Effects of the injection molding processing settings on the phase morphology and mechanical anisotropy of thermoplastic vulcanizates. Polymer Engineering & Science, 64(1), 154-169.
Mentges, Noah; Çelik, Hakan; Dahlmann, Rainer & Hopmann, Christian
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Modelling the effects of process induced phase morphology on the mechanical response of thermoplastic vulcanisates under quasi-static loading using representative volume elements, International Rubber Conference Organisation (IRCO) (Hrsg.), IRC RubberCon, Edinburgh, UK, 2023
MENTGES, N.; ÇELIK, H.; DAHLMANN, R. & HOPMANN, C.
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Reverse engineering calibration method of constituents properties for multi-scale simulations of injection moulded thermoplastic vulcanisate parts, Institut für Kunststoffverarbeitung (IKV) (Hrsg.), Proceedings of the 32nd international Colloquium Plastics Technology, Düren, Shaker Verlag, 2024, S. 163–173
MENTGES, N.; ÇELIK, H.; DAHLMANN, R. & HOPMANN, C.
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An anisotropic hyperelastic-plastic material model for the process-related material response of TPV, SPE (Hrsg.), ANTEC 2025, Philadelphia, PE, USA, 2025
MENTGES, N.; ÇELIK, H.; ERDOĞDU, Y. E.; ZEKORN, C.; DAHLMANN, R. & HOPMANN, C.
