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%0 Thesis %A Reuvers, Marie-Christine %T Multiphysics modeling and experimental analysis of fiber-reinforced polymers across scales %I Rheinisch-Westfälische Technische Hochschule Aachen %V Dissertation %C Aachen %M RWTH-2025-07151 %P 1 Online-Ressource : Illustrationen %D 2025 %Z Veröffentlicht auf dem Publikationsserver der RWTH Aachen University %Z Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2025 %X Nowadays, the growing demand for cost-effective, customizable, and reusable materials in the domains of mobility and transport, as well as consumer goods, has led to an increased significance of fiber-reinforced thermoplastics (FRTPs). Nonetheless, the industrial processing of FRTPs in terms of (thermo-)forming processes is still associated with costly and timeconsuming trial and error processes to adjust the material design and processing parameters. Still, oftentimes, unwanted deformations or even defects in the components arise due to thermal gradients and residual stresses within the material that need to be eliminated. In this context, numerical simulation tools, such as, for example, digital twins (i.e., the virtual representation of physical objects), can be employed in the conception and development phase of products and processes to improve efficiency, shorten development cycles, and identify potential error sources. In particular, the finite element method (FEM) has established itself as a suitable tool for the simulation of complex technical problems due to steadily increasing computational resources. The accuracy and reliability of the numerical predictions are, however, highly dependent on the quality of the employed material model. Thereby, the material behavior on the structural level is determined by the underlying microstructure and its associated characteristics. Especially fiber-reinforced semi-crystalline polymers (SCPs) represent a challenging material, due to their complex (time-dependent) inelastic deformations and dependencies on both the temperature and the temperature history. Consequently, the internal structure of FRTPs must be taken into account during model development by incorporating information across various scales.Multiscale modeling schemes can provide valuable insights into the overall constitutive response of the material. However, these simulations are generally computationally expensive. In order to reduce the computational cost and develop frameworks suitable for industry applications, hierarchical approaches have been developed and applied. The objective, and simultaneously the challenge, is to reduce computational costs and experimental effort while preserving high accuracy and validity across a broad spectrum of process parameters.The given cumulative dissertation comprises a collection of journal articles that contribute to the aforementioned research topics. It aims to develop a multiphysical framework for fiberreinforced SCPs, including the impact of temperature and temperature history across various scales. Starting with the motivation and corresponding research-relevant questions, followed by an overview of the current literature.In the first paper, a thermo-mechanically coupled constitutive model is developed for semicrystalline polyamide 6 blends. Based on an extensive experimental data set, comprising mechanical and thermal tests, a visco-elastic, elasto-plastic approach is chosen in which nonlinear relaxation, strain hardening, and a tension-compression asymmetry in yielding are considered. The degree of crystallinity (DOC) serves as a constant input parameter, which significantly influences the material response.Subsequently, a micromechanical and microthermal analysis is conducted in the second paper, employing the aforementioned matrix framework accompanied by a detailed experimental analysis of the composite’s behavior at various temperatures. Thus, an experimental and virtual data base is generated for a wide range of process parameters.The third paper’s objective is to extend the aforementioned micromechanical matrix model to represent glass-fiber reinforced polyamide 6 on the macroscale. Therefore, mechanical and thermal anisotropy is incorporated into the framework and, subsequently, characterized with the data base from the second paper. The DOC is now treated as a non-constant internal variable depending on the temperature history. Finally, a full 3D thermoforming simulation isconducted. The validity of the presented approach is verified by comparison of the numerical material response with experimental data across all material scales. %F PUB:(DE-HGF)11 %9 Dissertation / PhD Thesis %R 10.18154/RWTH-2025-07151 %U https://publications.rwth-aachen.de/record/1017118