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- Journal of Mechanical Design
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- National Science Foundation
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Abstract Recent studies have shown that reconfigurable acoustic arrays inspired from rigid origami structures can be used to radiate and focus acoustic waves. Yet, there is a need for exploration of single-degree-of-freedom deployment to be integrated with such arrays for sake of tailoring wave focusing. This research explores a reconfigurable acoustic array inspired from a regular Miura-ori unit cell and threefold-symmetric Bricard linkage. The system focuses on acoustic waves and has single-degree-of-freedom motion when incorporated with a modified threefold-symmetric Bricard linkage. Three configurations of the array are analyzed where array facets that converge towards the center axis are considered to vibrate like baffled pistons and generate acoustic waves into the surrounding fluid. An analytical model is constructed to explore the near-field acoustic focusing behavior of the proposed acoustic array. The wave focusing capabilities of the array are verified through proof-of-principle experiments. The results show that the wave focusing of the array is influenced by the geometric parameters of the facets and the relative distance of facets to the center axis, in agreement with simplified ray acoustics estimates. These findings underscore the fundamental relationship between focusing sound radiators and geometric acoustics principles. The results encourage broader exploration of acoustic array designs inspired from integrated single-degree-of-freedom linkages and origami structures for sake of straightforward array deployment and reconfiguration.more » « less
Recent studies have exemplified the potential for curved origami-inspired acoustic arrays to focus waves. Yet, reconfigurable structures that adopt curvatures are often difficult to translate to practice due to mechanical deformation of the facets that inhibit straightforward folding. In addition, not all tessellations that curve upon folding are also flat-foldable, which is a key advantage of portability inherent to many origami-inspired structures. This research introduces a new concept of partially activated reconfigurable acoustic arrays as a means to mitigate these drawbacks. Here, tessellations are studied where a subset of the facet surfaces are considered to radiate acoustic waves. The analytical results reveal focusing behaviors in such arrays that are otherwise not manifest for the array when fully activated. The focused waves are more intense in amplitude and space for partially activated arrays than fully activated counterparts. These trends are verified by experiment and are also found to be applicable to multiple reconfigurable array geometries. The results encourage broader study of the design space accessible in reconfigurable arrays to capitalize on all of the functionality afforded by origami-inspired wave guiding structures.more » « less
Spherically focused transducers have been long relied on to target acoustic energy delivery. Yet, these structures have limitations with respect to size and mobility for medical treatment applications. Recent developments in the field of reconfigurable structures reveal that the ancient art of origami inspires new platforms by which to enable spherical shapes that are additionally foldable for ease of transport. This research explores the opportunities for a unique, flat foldable doubly curved tessellated array to enable wave focusing capability similar to an ideal medical transducer shape: the spherical cap transducer. An analytical model of the doubly curved array is created and validated against data collected from a proof-of-concept array. The model is then leveraged to understand how the array design and complexity relatively govern the wave focusing capability. The findings show that doubly curved acoustic arrays do not require excessive facet refinement to achieve wave focusing similar to nominal spherically focused transducers. Yet, the optimal frequencies for which such capability is borne out vary substantially on the basis of array design. The discoveries of this research motivate future consideration of flat foldable doubly curved acoustic arrays for potential implementation into medical transducer development for hard-to-access surgical treatments.more » « less
The tremendous increase in the number of components in typical electrical and communication modules requires low-cost, flexible and multifunctional sensing, energy harvesting, and communication modules that can readily reconfigure, depending on changes in their environment. Current subtractive manufacturing-based reconfigurable systems offer limited flexibility (limited finite number of discrete reconfiguration states) and have high fabrication cost and time requirements. Thus, this paper introduces an approach to solve the problem by combining additive manufacturing and origami principles to realize tunable electrical components that can be reconfigured over continuous-state ranges from folded (compact) to unfolded (large surface) configurations. Special “bridge-like” structures are introduced along the traces that increase their flexibility, thereby avoiding breakage during folding. These techniques allow creating truly flexible conductive traces that can maintain high conductivity even for large bending angles, further enhancing the states of reconfigurability. To demonstrate the idea, a Miura-Ori pattern is used to fabricate spatial filters—frequency-selective surfaces (FSSs) with dipole resonant elements placed along the fold lines. The electrical length of the dipole elements in these structures changes when the Miura-Ori is folded, which facilitates tunable frequency response for the proposed shape-reconfigurable FSS structure. Higher-order spatial filters are realized by creating multilayer Miura-FSS configurations, which further increase the overall bandwidth of the structure. Such multilayer Miura-FSS structures feature the unprecedented capability of on-the-fly reconfigurability to different specifications (multiple bands, broadband/narrowband bandwidth, wide angle of incidence rejection), requiring neither specialized substrates nor highly complex electronics, holding frames, or fabrication processes.
Recent developments have shown that spatial structures devised from origami or low-dimensional rigid linkage mechanisms can be used to construct deployable arrays for antennas or satellites. Yet, some of these structures are limited to deployment in fixed planes or directions, or do not define straightforward processes for deployment. To surmount these limitations, this research introduces a reconfigurable single-degree-of-freedom spatial structure devised from a Kresling-inspired mechanism with integrated scissor arms. Analytical models are constructed to demonstrate compaction, deployment, and acoustic wave guiding capabilities of the proposed, modular structure. The influences of the geometric parameters on compaction, deployment, and scissor arm orientation are also explored, and reveal modular scissor arm behavior and large deployment-to-compaction area ratios. The acoustic wave guiding capabilities of the Kresling-inspired scissor structure are exemplified via a structure using spiral scissor arms, thereby proposing a novel concept for the construction of deployable wave guiding arrays. Experimental studies with model arrays complement the analytical findings of both the geometric reconfigurations and wave guiding functionality. Finally, out-of-plane configurations are depicted to demonstrate the three-dimensional shape change capabilities of the Kresling-inspired scissor structure. The results in this study encourage broader exploration of the interfaces between origami inspired structures and rigid linkage mechanisms.