Matthew Santer

Mechanical metamaterials are hierarchical structures that can be designed to possess exotic properties such as auxeticity, tunable stiffness, and bistability by optimizing the geometry of their microscale unit cells. This work develops a computational framework in which an arbitrary set of homogenized stress–strain goal points is defined, and topology optimization is employed to synthesize a unit cell to achieve the desired response. The framework extends the current state‐of‐the‐art by incorporating highly nonlinear phenomena such as internal contact, snap‐through buckling, and bistability in a single approach to capture a wide range of mechanical responses without the need for generating datasets, tuning parameters, or possessing prior knowledge of the optimal solution. Unit cells are generated for three challenging nonlinear responses and their behavior is validated via mechanical testing. The framework will enable the generation of highly nonlinear unit cells for metamaterials in applications such as morphing structures, soft robotics, and energy absorbing materials.

This study extends the functionality of ultra-thin carbon fibre composite tube flexures by interleaving a multi-layered conductive film along the laminate’s midline to enable data and power transmission across the structural joint. Conductive tracks, created by silver nanoparticle deposition onto a polyimide substrate, are encapsulated by a thermoplastic film to prevent short-circuits with the carbon fibres. The paper first establishes the mechanical stability of the integrated structure through analysis and testing, then investigates the electrical signal integrity and the feasibility of thermal actuation for a shape-memory use-case. Repeated moment-rotation tests showed a progressive reduction in locking moment. The conductive track remained functional, without showing an appreciable degradation in signal quality or electrical resistance. Resistive heating tests reaching higher temperatures caused adhesive failure between the thermoplastic film and the tracks in the stowed state, leading to local delamination and catastrophic failure of the laminate. These findings demonstrate that novel inkjet-printed conductive interleaves are a viable solution for digital signal and low-power transfers in laboratory conditions, raising the challenge of extending testing to space-like environments and improving the bond strength of the silver tracks for enhanced thermal durability. This methodology represents a significant step forward in terms of structural power integration, enabling ultra-lightweight harnesses to be directly integrated within highly strained deployable members with applications on small and large satellites, as well as next generation space structures, such as space-based solar power stations.

Among the different passive and active techniques for skin friction drag reduction for turbulent boundary layers, near wall forcing through moving walls is one of the most promising techniques at low Reτ. Fewer studies have looked at the mechanism at high Reτ, closer to flight conditions, largerly because, in this regime, numerical simulations become harder and experiments more challenging. To that end, there is the need of a systematic study for different surface waves and flow conditions. A new model using a kagome lattice is presented. It will be tested in the 10x5 wind tunnel at Reτ ≈ 8000. This work introduces an experimental setup which combines simultaneous measurements of surface displacement and velocity in the boundary layer. Here the results from a shorted version of the model at Reτ ≈ 1000 are presented to demonstrate the capability of the experimental setup.

This paper presents a novel deployable reflector concept based on the origami flasher pattern. The proposed folding architecture achieves rigid foldability for flasher patterns applied to doubly curved surfaces, allowing parabolic reflectors to be divided into a number of rigid panels for efficient stowage. Such an architecture provides an intermediate solution between current rigid-surface and flexible-surface reflectors, offering both surface precision and stowage compactness. The proposed patterns have a positive-finite degree of mobility, and so reliable and deterministic deployment is realized through suitable actuation. A Bayesian optimization approach is used in conjunction with kinematics and collision models in order to find optimal stowage patterns that accommodate finite thickness panels and supporting structures. For the generated optimal patterns, panel split line geometries are designed analytically to eliminate gaps while avoiding collision at panel edges during folding.