Authors: Christopher Czech, Paolo Guarneri, Niranjan Thyagaraja, Georges Fadel
J. Mech. Des.. 2015;137(4):041404-041404-9. doi:10.1115/1.4029518
J. Mech. Des.. 2015;137(4):041404-041404-9. doi:10.1115/1.4029518
Design requirements for engineered components are growing more complex and specific, with heavier emphases on efficiencies like weight and energy considerations. Often times, these considerations require the component to be constructed from materials that do not occur naturally. Instead, a metamaterial, one with properties not exhibited naturally by any known material, may be tailored to achieve the design requirements. Some examples include metamaterials with large strength to weight ratios, low energy loss moduli, or specified optical properties. However, designing these materials in a systematic manner has remained an engineering challenge, as linking the overall design requirements to the material requirements (a multiscale design problem) is not an elementary task. In this research, a method to design a shear layer metamaterial for a non-pneumatic wheel using a two-level optimization approach is presented. The design requirements for the shear layer metamaterial are determined in a top-level optimization, and mesostructures with the desired properties are designed using novel topology optimization methods at the material structure level. Inspired by honeycomb structures, a half-period staggered unit cell connectivity was utilized to change the inherent symmetry between unit cell layers. One geometry found using this staggered connectivity, the auxetic honeycomb (pictured below), is shown to be an optimum to the minimum volume topology optimization problem for materials subjected to pure shear boundary conditions. This is the first evidence supporting this structure as an optimum of a structural problem in shear deformation.
For the Abstract and Full Article see ASME's Digital Collection.
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