We give an example of a spacetime having an infinite thin rotating cylindrical shell constituted by a charged perfect fluid as a source. Then we disscuss the energy conditions and we show that our spacetime contains closed timelike curves. Trajectories of charged test particles both inside and outside the cylinder are also examined. Expression for the angular velocity of a circular motion insid...

In this paper, the influence of the elastic foundation on the free vibration and buckling of thin-walled piezoelectric-based functionally graded materials (FGM) cylindrical shells under combined loadings is investigated. The equations of motion are obtained by using the principle of Hamilton and Maxwell's equations and the Navier's type solution used to solve these equations. Material propertie...

In this study, the torsional stability analysis is presented for thin cylindrical with the functionally graded (FG) middle layer resting on the Winker elastic foundation. The mechanical properties of functionally graded material (FGM) are assumed to be graded in the thickness direction according to a simple power law and exponential distributions in terms of volume fractions of the constituents...

Most models of blown film extrusion are based on thin shell theory, which was first applied to these processes by Pearson and Petrie. There has been some contention in the literature as to the suitability of the thin shell model. More recently, Liu and coworkers presented an alternative quasi-cylindrical model that neglects longitudinal curvature but was reported to agree more closely with expe...

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...

Initial results of an investigation towards finding an efficient non-cylindrical fuselage configuration for a conceptual blended-wing-body flight vehicle were presented. A simplified 2-D beam column analysis and optimization was performed first. Then a set of detailed finite element models of deep sandwich panel and ribbed shell construction concepts were analyzed and optimized. Generally these...

Using multi-layers method (MLM), a semi-analytical solution have been derived for determination of displacements and stresses in a thick cylindrical shell with variable thickness under non-uniform pressure. Three different profiles (convex, linear and concave) are considered for the variable thickness cylinder. Given the existence of shear stress in the thick cylindrical shell due to thickness ...

In this paper a study on the vibration of thin cylindrical shells with ring supports and made of functionally graded materials (FGMs) composed of stainless steel and nickel is presented. The properties are graded in the thickness direction according to a volume fraction power-law distribution.The cylindrical shells with ring supports which are arbitrarily placed along the shell and impose zero ...