Characterisation and Optimisation of Lattice Structures Embedded with Phase Change Materials

In engineering fields where mass is a design-driving parameter, holistic mass reduction via multi-functionality is seen as a key enabler for further improvement of systems' performance. This research addresses the upcoming need for multi-functional structures capable of concurrently managing thermal control, energy storage, and load-bearing requirements. An investigation on the thermal and mechanical properties of lattice structures incorporating Phase Change Materials (PCMs) is described throughout this thesis. The work commences with an analytical description of the geometry of lattice structures. Then, it delves into the exploration of the effective thermophysical properties of the homogenised composite material, followed by meticulous validation through experimental methodologies. The impact of natural convection on the expansion of the melting front within the medium is considered as well. To elucidate how the presence of the PCM influences the structural integrity of the lattice, numerical and experimental analyses are performed for the PCM-infused lattice structures, focusing on the stability of the struts when the PCM is frozen. Furthermore, the thesis introduces a multi-variate optimisation framework designed to offer novel pathways for topology optimisation of lattice structures. This framework enables the exploration of optimal configurations by considering multiple variables simultaneously, providing a comprehensive approach to tailor the performance of such composites. The findings of this research contribute to a deeper understanding of the thermal and mechanical behaviour of cellular solids embedded with PCMs, providing valuable insights for applications in thermal energy storage, thermal management systems, and other related fields.