Internally architectured materials with directionally asymmetric friction

Bimodal mobility actuated by inertial forces with surface elastic bodies in microgravity

This paper presents bimodal mobility actuated by inertial forces with elastic bodies for an exploration robot in a microgravity environment. The proposed bimodal locomotion mechanism can selectively achieve vibration propulsion or rotational hopping mode based on centrifugal force and reaction torque exerted by the control of a single eccentric motor, where the rotational hopping is the primary locomotion mode for practical applications. The bimodal mobility performance under microgravity is experimentally examined using an air-floating testbed. Furthermore, we also present theoretical modeling of the bimodal mobility system, and the model is verified by comparison with the experiments.

Deformation mechanics of non-planar topologically interlocked assemblies with structural hierarchy and varying geometry

Structural hierarchy is known to enhance the performance of many of Nature's materials. In this work, we apply the idea of hierarchical structure to topologically interlocked assemblies, obtained from measurements under point loading, undertaken on identical discrete block ensembles with matching non-planar surfaces. It was demonstrated that imposing a hierarchical structure adds to the load bearing capacity of topological interlocking assemblies. The deformation mechanics of these structures was also examined numerically by finite element analysis. Multiple mechanisms of surface contact, such as slip and tilt of the building blocks, were hypothesised to control the mechanical response of topological interlocking assemblies studied. This was confirmed using as a model a newly designed interlocking block, where slip was suppressed, which produced a gain in peak loading. Our study highlights the possibility of tailoring the mechanical response of topological interlocking assemblies using geometrical features of both the element geometry and the contact surface profile.