Showing papers by "Ryan L. Harne published in 2022"

Rapid Pneumatic Control of Bimodal, Hierarchical Mechanical Metamaterials

Abstract: Recent attention to pneumatically pressurized mechanical metamaterials has identified opportunity for large shape change and mechanical properties adaptation through the collective exploitation of reconfigurable internal structures and enclosed cavities. Yet, many of these ideas are found to act in smooth, continuous ways at moderate rate. This research explores a new class of bimodal, hierarchical mechanical metamaterials that exemplify rapid change of mechanical behavior by exploiting pneumatic pressure as a means to cross bifurcation. A lattice structure with periodic square cavities is presented as a model metamaterial to highlight important design considerations and mechanical behavior. An analytical model is formed to delineate the multimodal boundaries in a high‐dimensional parameter space, while numerical simulations and experiments confirm the presence of each modal characteristic. The studies reveal the high rate of change afforded by this embodiment of pressurized mechanical metamaterials and confirm the origin lay in harnessing elastic instability. Extensions to the idea are compared against the Kutzbach–Grübler criteria to articulate how other metamaterial networks may be leveraged in this way. The outcomes of this research may inspire methods for high‐rate shape and properties change via multimodal mechanical metamaterial assemblies, such as for soft robotic platforms.

Acoustic wave focusing from reconfigurable acoustic arrays based on a Bricard-Miura synthesis

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 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 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.

Ensuring the kids are alright: Ways to help students network with industry professionals in the age of virtual meetings and career fair disillusionment

Abstract: The pandemic has derailed the traditional networking vehicles to connect aspiring, ambitious students with industry professionals. As a result, the flow of young talent to best-fitting industry outlets is being misdirected. Moreover, many students are not inclined to accept virtual meetings as a replacement for face-to-face engagement while professionals often prefer virtual meetings as means to maximize productivity. The latter disparity has led to campus “career fairs” turning into stay-at-home experiences that students notoriously lament. Without bridges to network students with the right industry professionals to optimize hiring and onboarding processes, our society faces increasing early career turnover, loss of productivity, and disenchantment of young talent with the technical outlets that could await them. This talk will first clarify the crisis facing industries as a result of pandemic-motivated physical distancing practices. We will discuss lessons learned from recent attempts to foster genuine connections between students and the industry professionals they could work alongside in the future. The talk will conclude with a call to action on part of both students and professionals to collectively rebuild the networking system before a temporary disruption turns into a generational failure.

Multi-material stimuli-responsive hydrogels with optically induced actuation

Abstract: A vision for soft, autonomous materials entails synthesis of multiple senses in multifunctional materials where material response requires sensitivity to external stimuli. Stimuli-responsive hydrogels are of particular interest for optically induced mechanical response due to the ability to transform external stimuli into large, reversible shape change. Specifically, temperature-responsive hydrogels are broadly used and can be designed to achieve deformation through the photothermal effect as a result of surface plasmonic resonance of gold nanoparticles. Here, a multi-material stimuli-responsive hydrogel network with embedded gold nanoparticles is demonstrated in a unit cell pattern with anisotropic swelling behavior in response to visible light. Reversible, anisotropic swelling leads to bending motion that contributes to the development of soft, autonomous materials.

3D printed deployable origami patterns at intermediate folding configurations for wave guiding applications

Abstract: Origami-based engineering employs the use of complex reconfigurable structures for a variety of applications in science and engineering. Most origami-inspired structures are designed to be fully deployed, yet wave guiding arrays require deployment to stable intermediate folding configurations to focus waves. Furthermore, current research for origami-inspired wave guiding does not study kinetic and kinematic behavior during compaction and deployment. In this study, the force required to compact the Miura-ori unit cell with compliant joints is investigated for intermediate folding configurations. By starting at intermediate folding angles, the maximum force to reach a fully compact shape can be reduced by over an order of magnitude compared to starting at a flat state.