Reduced-Order Modeling and Design Optimization of Thermomechanical Shape Memory Alloy-Based Bistable Microactuators and Hyperelastic Material Systems

This dissertation presents computational approaches for modeling complex material behavior, focusing on shape memory alloys (SMAs) and hyperelastic materials. The goal is to improve both prediction accuracy and computational efficiency in simulations used for designing advanced materials and bistable microactuators. The work begins with a stabilized finite element formulation that addresses common numerical issues such as volumetric locking, shear locking, and hourglassing. This is achieved using incompatible displacement modes within a variational framework, ensuring stable and accurate results even for thin structures and nearly incompressible materials. Building on this, a fully thermomechanically coupled SMA material model is developed within the generalized standard material framework. The model captures key phenomena such as shape memory effect, superelasticity, and phase transformation. It is applied to simulate an SMA-based bistable microactuator, demonstrating its ability to predict complex coupled behavior and support actuator design. To reduce computational cost, reduced-order modeling techniques based on proper orthogonal decomposition (POD) are introduced. These methods significantly decrease the number of degrees of freedom while maintaining high accuracy. The reduced models show strong agreement with full finite element simulations, achieving substantial speed improvements. Finally, a reduced-order modeling approach for nearly incompressible hyperelastic materials is proposed using a three-field formulation combined with k-means clustering. The method efficiently captures large deformation behavior while further improving computational performance. Overall, the dissertation provides robust and efficient numerical tools for simulating advanced material systems and contributes to the development of high-performance engineering applications.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Christian-Albrechts-Universität zu Kiel

Year

2026

Author dc:creator

• Shamim, Muhammad Babar

Contributors dc:contributor

• Wulfinghoff, Stephan
• Wendler, Frank

• Shape memory alloy material modeling
• Bistable microactuator
• Reduced order modeling
• Incompatible displacement modes
• Nearly incompressible material

Repository record source_url

https://macau.uni-kiel.de/receive/macau_mods_00008117

OAI identifier oai:identifier

oai:macau.uni-kiel.de:macau_mods_00008117