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An ionic polymer-metal composite (IPMC) consisting of a thin perfluorinated ionomer (usually, Nafion or Flemion) strip, platinum, and/or gold plated on both faces and neutralized by a certain amount of appropriate cations undergoes large bending motion when, in a hydrated state, a small electric field is applied across its thickness. When the same membrane(More)
The cluster morphology in a water-swollen Na®on per¯uorinated membrane is studied using a micromechanics approach. The cluster size is determined from the minimization of the free energy as a function of the equivalent weight of Na®on, the volume fraction of water, and the temperature, taking into account the electrostatic dipole interaction energy, the(More)
This paper presents the results of a systematic comparative study of the dynamic thermomechanical response of Ti± 6Al±4V alloys with three di€erent microstructures. Two of the alloys are produced by the hot isostatically pressed technique using rapidly solidi®ed granules, with one alloy milled prior to hot pressing. Experiments are performed over a broad(More)
Incorporation of ceramics in hybrid armor systems has resulted in significant weight reductions. They are an excellent prospect for the next-generation energy absorbing systems for vehicular protection. In this paper, it is demonstrated that the ballistic efficiency of ceramic tiles can be vastly improved by judiciously restraining them with membranes of(More)
Ionic polymer-metal composites ͑IPMCs͒ consist of a perfluorinated ionomer membrane ͑usually Nafion ® or Flemion ® ͒ plated on both faces with a noble metal such as gold or platinum and neutralized with the necessary amount of counterions that balance the electrical charge of anions that are covalently fixed to the backbone ionomer. IPMCs are electroactive(More)
The compressive response of a NiTi shape-memory alloy is investigated at high strain rates, using UCSDÕs modified split Hopkinson pressure bar and a mini-Hopkinson bar with specially designed striker bars. To obtain a constant strain rate during the formation of the stress-induced martensite phase in a Hopkinson test, a copper-tube pulse shaper of suitable(More)
A method for homogenization of an elastic composite with periodic microstructure is presented, focusing on the Floquet-type elastic waves. The resulting homogenized frequency-dependent elasticity and mass density then automatically satisfy the overall conservation laws and by necessity produce the exact dispersion relations. It is also shown that the(More)
a r t i c l e i n f o a b s t r a c t Stress-wave propagation in solids can be controlled through imposing a gradual change of anisotropy in the material elasticity tensor. In this study, a transversely isotropic material is incorporated with a smoothly varying axis of anisotropy. It is shown that if this axis initially coincides with the stress-wave(More)
The repeated fracture–healing characteristics of 2MEP4F polymer, a cross-linked polymer based on Diels–Alder cycloaddition, are systematically and quantitatively evaluated using a sample geometry that allows for controlled incremental crack growth so that the cracked sample remains in one piece after the test, improving our ability to realign the fracture(More)