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Abstract Zero Poisson’s ratio structures are a new class of mechanical metamaterials wherein the absence of lateral deformations allows the structure to adapt and conform their geometries to desired shapes with minimal interventions. These structures have gained attention in large deformation applications where shape control is a key performance attribute, with examples including but not limited to shape morphing, soft robotics, and flexible electronics. The present study introduces an experimentally driven approach that leads to the design and development of (near) zero Poisson’s ratio structures with considerable load-bearing capacities through concurrent density and architecture gradations in hybrid honeycombs created from hexagonal and re-entrant cells. The strain-dependent Poisson’s ratios in hexagonal and re-entrant honeycombs with various cell wall thicknesses have been characterized experimentally. A mathematical approach is then proposed and utilized to create hybrid structures wherein the spatial distribution of different cell shapes and densities leads to the development of honeycombs with minimal lateral deformations under compressive strains as high as 0.7. Although not considered design criteria, the load-bearing and energy absorption capacities of the hybrid structures are shown to be comparable with those of uniform cell counterparts. Finally, the new hybrid structures indicate lesser degrees of instability (in the form of cell buckling and collapse) due to the self-constraining effects imposed internally by the adjacent cell rows in the structures.
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Transferring Soft Doubly Re-Entrant Microstructures For Mechanically Resilient Omniphobic Surfaces
Omniphobic surfaces, capable of repelling all types of liquids, are fundamentally reliant on the micro/nano doubly re-entrant structures, these overhanging structures, however, are prone to break under mechanical loading. Here, we report a robust technique to faithfully transfer an array of soft doubly re-entrant microstructures onto a target substrate, circumventing the limitation of demolding soft overhang structures, to realize a resilient omniphobic surface for the first time. The resulting surface not only exhibits omniphobic property, but also robust durability after substantial normal and shear mechanical stresses. The side view of the deformation and recovery of the structures against mechanical loads was captured under a microscope to help reveal the underlying mechanism. The innovative method presented in this study is scalable for the production of mechanically robust, omniphobic surfaces on a large scale. Such advancement facilitates the large-scale manufacturing of durable micro- and nanoscale surface textures, making them viable for practical applications.
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- Award ID(s):
- 2225964
- PAR ID:
- 10533939
- Publisher / Repository:
- Hilton Head Workshop 2024: A Solid-State Sensors, Actuators and Microsystems Workshop
- Date Published:
- Page Range / eLocation ID:
- 275-277
- Format(s):
- Medium: X
- Location:
- Hilton Head Island, SC, USA
- Sponsoring Org:
- National Science Foundation
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