Deformation and Strain Energy Anomalies in Bistable and Nonlocal Mechanical Metamaterials
thesisposted on 01.08.2019, 00:00 by Larry Appiah Danso
Mechanical metamaterials are materials with preconceived elastic properties like negative Poisson’s ratio, negative compressibility, negative stiffness, etc. that cannot be achieved by natural materials. In recent times, this class of metamaterials have garnered significant research interest due to the interesting functionalities and applications attainable when such materials are used in composites, intelligent structures and resilient systems. Bistable structures exhibit snap-through displacement behavior that counter deficiencies like fatigue and slow response time found in active materials which makes them relevant for designing actuators, sensors, soft robots, deployable structures etc. Nonlocal periodic lattices may possess bandgaps in their deformation decay spectrum that allow for complete blockage of Raleigh modes of deformation and the ability to reprogram deformation patterns due to the reverse Saint Venant edge effect. This thesis presents a detailed study on the design and analysis of bistable elastic structures that showcase linear contraction on application of a tensile load and nonlocal lattice material that possess the ability to divert maximal strain energies induced by an applied point load or indentation force thereby shielding integrity of material’s interior. The unusual elastic properties of these structures and materials signify that their deformation mechanisms could be programmed to possess functionalities such as stress and strain alleviation, vibration control, strain energy storage that are unrealistic with natural materials.