The viscoelastic behavior of polymer composites decreases the deployment force and the postdeployment shape accuracy of composite deployable space structures. This paper presents a viscoelastic model for single-ply cylindrical shells (tape springs) that are deployed after being held folded for a given period of time. The model is derived from a representative unit cell of the compositematerial,...

The unsteady two-dimensional flow of a viscoelastic second-grade fluid impinging on an infinite plate is considered. The plate is making harmonic oscillations in its own plane. A finite difference technique is employed and solutions for small and large frequencies of the oscillations are obtained. 1. Introduction. In the past two decades, the importance of non-Newtonian viscoelastic liquids hav...

A simple model for the rheological behavior of concentrated colloidal dispersions is developed. For a suspension of Brownian hard spheres there are two contributions to the macroscopic stress: a hydrodynamic and a Brownian stress. For small departures from equilibrium, the hydrodynamic contribution is purely dissipative and gives the high-frequency dynamic viscosity. The Brownian contribution h...

In this paper, the numerical simulation for nano-indentation is performed to measure time-dependent behavior of polymeric films. The possibility to extract the relaxed shear modulus of the polymer is evaluated using a rigid ball indenter. The viscoelastic behavior of the polymer was represented by the standard model. The effects of Poisson’s ratio are also discussed.

Using the quasi-linear viscoelastic model proposed by Fung for the description of the viscoelastic properties of soft biological tissues, the parameters governing their time-dependent behavior are commonly estimated from relaxation experiments. Exact quantification is possible from the response to a step change in the strain. Since it is physically impossible to realize a true step change in th...

This paper characterized bovine extraocular muscles (EOMs) using creep, which represents long-term stretching induced by a constant force. After preliminary optimization of testing conditions, 20 fresh EOM samples were subjected to four different loading rates of 1.67, 3.33, 8.33, and 16.67%/s, after which creep was observed for 1,500 s. A published quasilinear viscoelastic (QLV) relaxation fun...

background: one area of nanoscience deals with nanoscopic interactions between nanostructured materials and biological systems. to elucidate the effects of the substrate surface morphology and viscoelasticity on cell proliferation, fractal analysis was performed on endothelial cells cultured on nanocomposite samples based on silicone rubber (sr) and various concentrations of organomodified nano...

In our study of the aging phenomena in silica suspensions we immersed precipitated silica particles in methyl-terminated PDMS (silicone oil), mineral oil, and glycerol/water and measured their viscoelastic properties as a function of time. We found that the samples based on silicone oil, initially of a pasty consistence, became fluid-like after a period of about three weeks. Aqueous samples age...

There are many tactile devices for indentation examinations to measure mechanical properties of tissue. The purpose of this paper is to develop a portable indentation robotic device to show its usability for measuring the mechanical properties of a healthy abdominal tissue. These measurements will help to develop suitable mathematical models representing abdominal tissue. A 1-DOF portable robot...

The viscoelastic properties of three commercially available resin-based composites (FiltekTM P60, FiltekTM Supreme, and FiltekTM Z250; 3M ESPE, Bracknell, UK) were measured to determine the effect of beverages on their storage moduli and damping ratios. Rectangular samples of the three hybrid composites were immersed in three beverages at 37 °C for 1, 7, 30, and 60 days. At each time interval, ...