Dielectric capacitors with mechanical load-bearing capability have been constructed by laminating glass-epoxy prepregs with metalized film electrodes. Mechanical characterization and high-voltage testing are used to quantify the elastic modulus, mechanical strength, and dielectric energy density of these structural devices. An approach for predicting mass savings in systems utilizing multifunctional material structures is also presented. The experimental results show that, in spite of increases in void content with fiber volume fraction, overall structural capacitor performance is greatest at maximum fiber volume fraction. At these high-fiber volume fractions, the overall multifunctional performance of the structural capacitors is predicted to provide mass and volume savings over conventional designs.

Structural capacitors, supercapacitors, and batteries are fabricated and tested, using modified materials and processes based on conventional fiber-reinforced polymer matrix composites. Printed circuit board prepregs are used to create structural capacitors that demonstrate good dielectric energy density and mechanical stiffness and strength. Structural supercapacitors are created using carbon fabric electrodes and a liquid-plasticized, epoxy polymer electrolyte. A similar construction is used to create structural batteries, by substituting LiFePO4-coated carbon fiber fabric as cathodes opposed to unmodified carbon fiber anodes. Structural batteries and supercapacitors show basic electrochemical and mechanical functionality. However, significant additional work is required to improve their quantitative performance to values of practical engineering value.

This article details the design, fabrication, and application of a mechatronic arm exoskeleton for firearm aim stabilization (MAXFAS), which senses and damps involuntary tremors in the arm. Human subject experiments were carried out using the device in a simulated shooting and aiming task. Results indicate that MAXFAS reduced arm tremors and improved shooting performance while wearing the device. Residual performance improvement after removing the device and possible training function of MAXFAS will also be discussed.

As U.S. Army systems and vehicles become more dependent on electronic devices and subsystems, there is an increasing need for improving the mass-and volume-efficiency of energy storage components. The conventional approach for saving mass and volume is to increase component energy density. Alternatively, overall system weight can be reduced by replacing purely structural components, such as armor or frame members, with structures that also store energy. Specifically, we are developing capacitors that can also carry structural loads by intercalating glass fiber reinforced polymer dielectric layers with metallized polymer film electrodes.In previous work, we developed a metric, the multifunctional efficiency (MFE), for comparing various structural capacitor preparations and guiding multifunctional design. Modeling and characterization of fiber composite-based structural capacitors has shown that the MFE is sensitive to fiber shape, orientation, volume fraction, and dielectric constant. In this work, various dielectric materials are studied against this MFE metric and the effect of fiber properties and volume fraction on MFE is explored experimentally.

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