Hyperelastisch-plastisches Materialmodell zur Beschreibung der Anisotropie in thermoplastischen Vulkanisaten
Thermoplastische Vulkanisate (TPV) revolutionieren die Elastomerverarbeitung, doch ihre prozessbedingte Anisotropie stellt neue Herausforderungen für die Strukturauslegung. Ein innovatives Materialmodell, basierend auf mikromechanischen Untersuchungen und semi-physikalischen Ansätzen, ermöglicht erstmals eine präzise Berechnung des anisotropen Werkstoffverhaltens. Dies ebnet den Weg für effiziente Simulationen und die optimierte Auslegung von TPV-Bauteilen.
Initial situation / problem:
Due to their multiphase structure, thermoplastic vulcanisates (TPV) combine the outstanding rubber-elastic properties of elastomers with the efficient processability and recyclability of thermoplastics. As a result, more and more elastomer components are being replaced by TPV. When designing structural components made of TPV, new challenges arise, such as the process-related anisotropy of the material. This occurs due to the high shear rates in the injection moulding process and the resulting orientation and distortion processes of the elastomer particles. Current material models are not capable of mapping the process-related anisotropy of this class of materials. Only by taking this effect into account can a more accurate prediction of component behavior be made.
Objective:
As part of the project presented, the interactions between the morphological configuration of the material and the macroscopic material response were investigated on the basis of micromechanical investigations. Based on this, an analytical material model was developed which describes the mechanical behavior of thermoplastic vulcanisates, taking into account the local phase morphology. This is done in consideration of the morphological structure.
Solution and results:
Statistically representative volume elements (RVE) were used to investigate the correlation between the degree of distortion and the mechanical material response. These RVE models represent geometric equivalents of the phase configuration of the TPV under consideration. To generate the RVE models, an algorithm was developed that can map the high elastomer content and distortions in thermoplastic vulcanisates. Parameter studies were used to gain insights into the interactions for the development of an analytical material model. The material model developed is based on a semi-physical homogenisation approach at the molecular level. By implementing an interconnection of mechanical replacement models to represent the thermoplastic and elastomer phases and introducing a molecule orientation distribution, the
characteristic anisotropic elastic-plastic material behavior of TPV. The developed material model is capable of efficiently calculating the component behavior of TPV components, taking into account the process-related anisotropy. The necessary prediction of the degree of distortion in the injection moulding simulation is not yet possible. In the long term, an integrative modeling approach is to be developed as part of the research strategy. Suggestions for solving these issues and participation in project consortia are welcome.
Project data and funding
The research project was funded by the German Research Foundation (DFG) – 448100263. Our sincere thanks go to her!
Project duration: 2020-2024
Project partners
