In this research we study the dynamics of a coupled linear oscillator-bistable energy harvester system. The method of harmonic balance and perturbation analysis are used to predict the existence and stability of the bistable device interwell vibration. The influences of important parameters on tailoring the coupled system response are investigated to determine strategies for improved energy harvesting performance. We demonstrate analytically that for excitation frequencies in a bandwidth less than the natural frequency of the uncoupled linear oscillator having net mass that is the combination of the bistable and linear bodies, the bistable harvester dynamics may be substantially intensified as compared to a single (individual) bistable harvester. In addition, the linear-bistable coupled system may introduce a stable out-of-phase dynamic around the natural frequency of the uncoupled linear oscillator, enhancing the performance of the harvester by providing a second interwell response not possible when using a single bistable harvester. Key analytical findings are confirmed through numerical simulations and experiments, validating the predicted trends and demonstrating the advantages of the coupled system for energy harvesting.

Origami-inspired structures have a rich design space and possess the ability to undergo large and complex yet predictable shape transformations, offering new opportunities for the development of deployable systems. There has been growing interest in such deployable systems that can extend uniaxially into tubes and booms. The Kresling pattern, which arises from the twist buckling of a thin cylinder and can exhibit multistability, offers great potential. However, much remains to be understood regarding the features that lead to effective deployment. Furthermore, origami deployment is fundamentally a dynamic process, yet its dynamic behaviors remain unexplored. These dynamics may be complex due to the strong nonlinearity, bistability, and potential for off-axis motions. Hence, this research seeks to uncover the deployment dynamics of Kresling structures for a range of system geometries and corresponding deployment strategies.It employs a full, six-degree-of-freedom model to provide insight into both axial and off-axis dynamics, revealing that the variation of key geometric parameters may lead to regions with qualitatively distinct mechanical responses. Results illustrate the sensitivity of dynamic deployment to changes in initial condition and small variations in geometric design. Further, analyses show how certain geometries and configurations affect the stiffness of various axial and off-axis deformation modes, offering guidance on the design of systems that deploy effectively while mitigating the effects of off-axis disturbances. Overall, the research outcomes suggest the strong potential of Kresling-based designs for deployable systems with robust and tunable performance.

We present an approach to achieve adaptable band structures and nonreciprocal wave propagation by exploring and exploiting the concept of metastable modular metastructures. Through studying the dynamics of wave propagation in a chain composed of finite metastable modules, we provide experimental and analytical results on nonreciprocal wave propagation and unveil the underlying mechanisms that facilitate such unidirectional energy transmission. In addition, we demonstrate that via transitioning among the numerous metastable states, the proposed metastructure is endowed with a large number of bandgap reconfiguration possibilities. As a result, we illustrate that unprecedented adaptable nonreciprocal wave propagation can be realized using the metastable modular metastructure. Overall, this research elucidates the rich dynamics attainable through the combinations of periodicity, nonlinearity, spatial asymmetry, and metastability and creates a class of adaptive structural and material systems capable of realizing tunable bandgaps and nonreciprocal wave transmissions.

In contrast to monitoring natural frequency shift, bifurcation-based sensing techniques utilize dramatic switches in response amplitude to detect structural change. We demonstrate a highly sensitive bifurcation-based sensing method requiring only the monitored structure, a transduction mechanism, and bistable electric circuitry. The system configuration is broadly applicable from, e.g., microscale mass sensing to structural health monitoring. In contrast to single bifurcation events of past techniques, the present methodology introduces new bifurcations that may be utilized sequentially for monitoring numerous thresholds of structural parameter change. We show that bifurcation-based sensing potential and versatility is greatly advanced. V

Recent studies on periodic metamaterial systems have shown that remarkable properties adaptivity and versatility are often the products of exploiting internal, coexisting metastable states. Motivated by this concept, this research develops and explores a local-global design framework wherein macroscopic system-level properties are sought according to a strategic periodic constituent composition and assembly. To this end and taking inspiration from recent insights in studies of multiphase composite materials and cytoskeletal actin networks, this study develops adaptable metastable modules that are assembled into modular metastructures, such that the latter are invested with synergistic features due to the strategic module development and integration. Using this approach, it is seen that modularity creates an accessible pathway to exploit metastable states for programmable metastructure adaptivity, including a near-continuous variation of mechanical properties or stable topologies and adjustable hysteresis. A model is developed to understand the source of the synergistic characteristics, and theoretical findings are found to be in good agreement with experimental results. Important design-based questions are raised regarding the modular metastructure concept, and a genetic algorithm (GA) routine is developed to elucidate the sensitivities of the properties variation with respect to the statistics amongst assembled module design variables. To obtain target multifunctionality and adaptivity, the routine discovers that particular degrees and types of modular heterogeneity are required. Future realizations of modular metastructures are discussed to illustrate the extensibility of the design concept and broad application base.