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The passive attributes of skeletal muscle "material" often have origins in nanoscale architecture and functionality where geometric frustrations directly influence macroscale mechanical properties. Drawing from concepts of the actomyosin network, this study investigates a modular, architected material system that leverages spatial constraints to generate multiple stable material topologies and to yield large adaptability of material mechanical properties. By exploiting the shearing actions induced on an actomyosin-inspired assembly of modular material constituents, new intriguing material behaviors are cultivated, including strong metastability and energy-releasing state transitions. Experimental, numerical, and analytical studies reveal that such passive attributes can be tailored by geometric constraints imposed on the modular material system. The geometric parameters can also introduce a bias to the deformations, enabling a programmable response. By invoking the spatial constraints and oblique, shear-like motions inherent to skeletal muscle architecture, this research illustrates new potential for architected material systems that exploit locally tunable properties to achieve targeted macroscopic behaviors.

The effective bulk modulus of working fluids plays an important role in the control of hydraulic actuation systems because of its effect on the system response time and performance. Therefore, to ensure good control, monitoring the effective bulk modulus of the working fluids is an important task. Current methods normally require precision test equipment consisting of many complex components. The size of these devices is large and thus makes online measurement impractical. In this research, we develop a new on-line technique to estimate effective bulk modulus of the working fluids based on measurements of the impedance of piezoelectric transducers. The idea is to generate a sensitivity curve characterizing the relationship between the effective bulk modulus and the impedance resonant frequency via either off-line numerical simulation or off-line experimental calibration; the curve can then be used for monitoring the working fluids bulk modulus in an online manner. In this article, a simulation model is utilized to predict the peak resonance frequency of the impedance function and identify its dependency on the variation of the fluid bulk modulus. The new approach is then illustrated and a sensitivity curve is generated through comparing the simulation results with experimental data.

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An approach for vibration delocalization of nearly periodic structures using piezoelectric networks with active coupling enhancement is presented. Piezoelectric networks are synthesized to reduce the localization effect by absorbing the vibratory mechanical energy into the electric circuits and distributing it through an additional strong electrical wave channel. The effectiveness of electro-mechanical coupling of the system is increased through the use of active actions via a negative capacitance circuit. It is demonstrated that the delocalization effect of the piezoelectric networks can be greatly enhanced by using the proposed treatment.