In a soft elastic film compressed on a stiff substrate, creases nucleate at preexisting defects and grow across the surface of the film like channels. Both nucleation and growth are resisted by the surface energy, which we demonstrate by studying creases for elastomers immersed in several environments--air, water, and an aqueous surfactant solution. Measurement of the position where crease chan...

Yi Han∗, Akshi Mohla∗, Xiao Huang†,‡, Wei Hong∗,†,¶ and Leann E. Faidley§ ∗Department of Aerospace Engineering Iowa State University, Ames, IA 50010, USA †Department of Materials Science and Engineering Iowa State University, Ames, IA 50010, USA ‡Department of Engineering Mechanics Tsinghua University, Beijing 100084, P. R. China §Department of Chemistry and Engineering Science Wartburg College...

The thrust of this project was to evaluate commercial conformal encapsulation candidates for low cost aerospace applications. The candidate conformal coatings evaluated in this study included silicone elastomers, epoxies, and Parylenes with bi-layer or tri-layer designs. Properties characterized in this study included mobile ion permeation and moisture ingress resistance, interfacial adhesion v...

We present a new finite deformation, dynamic finite element model that incorporates surface tension to capture elastocapillary effects on the electromechanical deformation of dielectric elastomers. We demonstrate the significant effect that surface tension can have on the deformation of dielectric elastomers through three numerical examples: (1) surface tension effects on the deformation of sin...

In response to a stimulus, a soft material deforms, and the deformation provides a function. We call such a material a soft active material (SAM). This review focuses on one class of soft active materials: dielectric elastomers. When a membrane of a dielectric elastomer is subject to a voltage through its thickness, the membrane reduces thickness and expands area, possibly straining over 100%. ...

The present paper demonstrates that the Hart-Smith constitutive model and the more recent Arruda and Boyce eight chains and Gent constitutive models are closely related. The ability of these three models to predict both small and large strain responses of rubbers is highlighted and equations that relate their material parameters are established. INTRODUCTION Elastomers exhibit a very complex me...

In this paper we present an approximation framework and theoretical convergence results for a class of parameter estimation problems for general abstract nonlinear hyperbolic systems. These systems include as a special case those modeling a large class of nonlinear elastomers.

The mechanical properties and morphology of polypropylene/wood flour (PP/WF) composites with different impact modifiers and maleated polypropylene (MAPP) as a compatibilizer have been studied. Two different ethylene/propylene/diene terpolymers (EPDM) and one maleated styrene-ethylene/butylene-styrene triblock copolymer (SEBS-MA) have been used as impact modifiers in the PP/WF systems. All three...

Liquid crystalline elastomers combine the ordering properties of liquid crystals with elasticity of crosslinked polymer networks. In monodomain (permanently aligned) elastomers, altering the orientational (nematic) order causes changes in the equilibrium sample length, which is the basis of the famous effect of large-amplitude reversible mechanical actuation. The stimulus for this effect could ...