Polymer composites reinforced by carbon nanotubes have been extensively researched for their strength and stiffness properties. Unless the interface is carefully engineered, poor load transfer between nanotubes (in bundles) and between nanotubes and surrounding polymer chains may result in interfacial slippage and reduced performance. Interfacial shear, although detrimental to high stiffness an...

This article compares resonant ultrasound spectroscopy ~RUS! and other resonant methods for the determination of viscoelastic properties such as damping. RUS scans from 50 to 500 kHz were conducted on cubical specimens of several materials including brass, aluminum alloys, and polymethyl ~methacrylate! ~PMMA!, a glassy polymer. Comparison of damping over the frequency ranges for broadband visco...

The Cauchy problem for a nonlinear elastic wave equation with viscoelastic damping terms is considered on the 3 dimensional whole space. Decay and smoothing properties of solutions are investigated when initial data sufficiently small; asymptotic profiles as t→∞ also derived.

Undulatory motion is common to many creatures across many scales, from sperm to snakes. These organisms must push off against their external environment, such as a viscous medium, grains of sand, or a high-friction surface; additionally they must work to bend their own body. A full understanding of undulatory motion, and locomotion in general, requires the characterization of the material prope...

The Kosloff & Kosloff (KK) absorbing-boundary method is shown to be a particular case of the split-PML method introduced by Bérenger. In its original form, the PML technique has been implemented for Maxwell’s electromagnetic equations. On the other hand, the KK method was applied to the Schrödinger and acoustic wave equations. Both techniques have subsequently widely been used in dynamic elasti...

Armored military vehicles have a harsh noise environment and many times the noise levels become almost an afterthought for the vehicle designers. There are numerous noise sources such as the engine, transmission, cooling fans, and track noise. The thick armor plating and the fact that the noise sources are inside the vehicle exacerbate the noise problem. This means there are few paths for the n...

In this paper we consider the following Timoshenko system φtt − (φx + ψ)x = 0, (0, 1)× (0,+∞) ψtt−ψxx + ∫ t 0 g(t−τ)(a(x)ψx(τ))xdτ +φx +ψ+b(x)h(ψt) = 0, (0, 1)×(0,∞) with Dirichlet boundary conditions where a, b, g, and h are specific functions. We establish an exponential and polynomial decay results. This result improves and generalizes some existing results in the literature.

The demand for silent bearing applications has started the research to asses the effect of a viscoelastic damping layer in the vicinity of the bearing, for example between the bearing outer ring and the housing. In order to predict the dynamic behaviour of rolling bearing applications a 3D nonlinear time dependent computational model is developed. Both the vibration generation and the vibration...

This paper is concerned with regular flows of incompressible weakly viscoelastic fluids which obey a differential constitutive law of Oldroyd type. We study the newtonian limit for weakly viscoelastic fluid flows in IR or T N for N = 2, 3, when the Weissenberg number (relaxation time measuring the elasticity effect in the fluid) tends to zero. More precisely, we prove that the velocity field an...

Hydroelectric power plants are known for their ability to cover variations of the consumption in electrical power networks. In order to follow this changing demand, hydraulic machines are subject to off-design operation. In that case, the swirling flow leaving the runner of a Francis turbine may act under given conditions as an excitation source for the whole hydraulic system. In high load oper...