In this paper an optimization problem for a cylindrical shell under an applied dynamical loading is discussed. The aim is to look for an optimal thickness of a shell to minimize the deformation when the shell is subject to an external timedependent force together with an initial impact. The volume of the shell has to stay constant during optimization. A model for the deflection is derived and a...

We explore an acoustic scattering cancellation shell for buoyant hollow cylinders submersed in a water background. A thin, low-shear, elastic coating is used to cancel the monopole scattering from an air-filled, neutrally buoyant steel shell for all frequencies where the wavelength is larger than the object diameter. By design, the uncoated shell also has an effective density close to the aqueo...

Vacuum expectation values of the field square and the energy-momentum tensor for the electromagnetic field are investigated for the geometry of a wedge with a coaxal cylindrical boundary. All boundaries are assumed to be perfectly conducting and both regions inside and outside the shell are considered. By using the generalized Abel-Plana formula, the vacuum expectation values are presented in t...

The use of intelligent nanocomposites in sensing and actuation applications has become quite common over the past decade. In this article, electro-thermo-mechanical nonlinear dynamic buckling of an orthotropic piezoelectric nanocomposite (PNC) cylindrical shell conveying viscous fluid is investigated. The composite cylindrical shell is made from Polyvinylidene Fluoride (PVDF) and reinforced by ...

A unified boundary element method ~BEM! is developed in this paper to model both the exterior acoustic field and the elastic shell-like structure in a coupled analysis. The conventional boundary integral equation ~BIE! for three-dimensional ~3D! elastodynamics is applied to thin shell-like structures which can have arbitrary shapes and small thicknesses. The nearly singular integrals existing i...

The stability of lightweight space structures composed longitudinal thin-shell elements connected transversely by thin rods is investigated, extending recent work on the cylindrical and spherical shells. role localization in buckling these investigated early transitions into post-buckling regime are unveiled using a probe that locally displaces structure. Multiple locations studied force versus...

We present an idealised model of gravitational collapse, describing a collapsing rotating cylindrical shell of null dust in flat space, with the metric of a spinning cosmic string as the exterior. We find that the shell bounces before closed timelike curves can be formed. Our results also suggest slightly different definitions for the mass and angular momentum of the string. Introduction A stat...

Nanocomposites provide new properties and exploit unique synergism between materials. Polyvinylidene fluoride (PVDF) is an ideal piezoelectric matrix applicable in nanocomposites in a broad range of industries from oil and gas to electronics and automotive. And boron nitride nanotubes (BNNTs) show high mechanical, electrical and chemical properties. In this paper, the critical torsional load of...