skip to main content


Title: Partially activated reconfigurable arrays to guide acoustic waves
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
Award ID(s):
2054970
NSF-PAR ID:
10339725
Author(s) / Creator(s):
; ;
Date Published:
Journal Name:
Journal of Intelligent Material Systems and Structures
Volume:
32
Issue:
20
ISSN:
1045-389X
Page Range / eLocation ID:
2529 to 2540
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. null (Ed.)
    Abstract Curved surfaces are often used to radiate and focus acoustic waves. Yet, when tessellated into reconfigurable surfaces for sake of deployability needs, origami-inspired acoustic arrays may be challenging to hold into curved shape and may not retain flat foldability. On the other hand, deployable mechanisms such as the Hoberman ring are as low-dimensional as many origami tessellations and may maintain curved shape with ease due to ideal rigid bar compositions. This research explores an interface between a Hoberman ring and Miura-ori tessellation that maintain kinematic and geometric compatibility for sake of maintaining curved shapes for sound focusing. The Miura-ori facets are considered to vibrate like baffled pistons and generate acoustic waves that radiate from the ring structure. An analytical model is built to reveal the near field acoustic behavior of acoustic arrays resulting from a Hoberman–Miura system synthesis. Acoustic wave focusing capability is scrutinized and validated through proof-of-principle experiments. Studies reveal wave focusing phenomena distinct to this manifestation of the acoustic array and uncover design and operational influences on wave focusing effectiveness. The results encourage exploration of new interfaces between reconfigurable mechanisms and origami devices where low-dimensional shape change is desired. 
    more » « less
  2. 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
  3. Abstract

    Origami, the ancient art of paper folding, has shown its potential as a versatile platform to design various reconfigurable structures. The designs of most origami-inspired architected materials rely on a periodic arrangement of identical unit cells repeated throughout the whole system. It is challenging to alter the arrangement once the design is fixed, which may limit the reconfigurable nature of origami-based structures. Inspired by phase transformations in natural materials, here we study origami tessellations that can transform between homogeneous configurations and highly heterogeneous configurations composed of different phases of origami unit cells. We find that extremely localized and reprogrammable heterogeneity can be achieved in our origami tessellation, which enables the control of mechanical stiffness and in-situ tunable locking behavior. To analyze this high reconfigurability and variable stiffness systematically, we employ Shannon information entropy. Our design and analysis strategy can pave the way for designing new types of transformable mechanical devices.

     
    more » « less
  4. 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.

     
    more » « less
  5. This work presents innovative origami optimization methods for the design of unit cells for complex origami tessellations that can be utilized for the design of deployable structures. The design method used to create origami tiles utilizes the principles of discrete topology optimization for ground structures applied to origami crease patterns. The initial design space shows all possible creases and is given the desired input and output forces. Taking into account foldability constraints derived from Maekawa's and Kawasaki's theorems, the algorithm designates creases as active or passive. Geometric constraints are defined from the target 3D object. The periodic reproduction of this unit cell allows us to create tessellations that are used in the creation of deployable shelters. Design requirements for structurally sound tessellations are discussed and used to evaluate the effectiveness of our results. Future work includes the applications of unit cells and tessellation design for origami inspired mechanisms. Special focus will be given to self-deployable structures, including shelters for natural disasters. 
    more » « less