New finite element modelling techniques for functional materials and devices

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This thesis focuses on modeling the mechanical behavior of two advanced products using the finite element method (FEM), along with enhancements for improved simulation accuracy. The first application introduces a hybrid production process for large ring-shaped devices with a wear-resistant outer layer made from metal matrix composite (MMC). This innovative process combines ring rolling and layer compaction into a single step, overcoming current limitations on ring size. A material model is developed to accurately describe the compaction of metal powders, which is then utilized in simulations of a powder-filled bar and ring during longitudinal and ring rolling processes. The second application addresses stents made from nickel-titanium alloys (Nitinol), characterized by intricate structures that require finite element models with numerous degrees of freedom, leading to extended computing times. To tackle this challenge, a novel finite element technology called the solid-beam element is introduced. The performance of this element is evaluated through various benchmark problems from existing literature. Ultimately, this technology is successfully employed to model stent structures, including a complete intracranial stent, demonstrating its effectiveness in enhancing simulation efficiency for complex geometries.