http://milad-engc.persiangig.com/Recent.pdf

Recent research advances on the dynamic analysis of composite shells: 2000-2009

This paper aims at investigating the effect of Carbon Nanotube (CNT) agglomeration on the free vibrations of laminated composite doubly-curved shells and panels reinforced by CNTs. The great performances of doubly-curved structures are joined with the excellent mechanical properties of CNTs. Several laminations schemes and various CNT exponential distributions along the thickness of the structures are considered. Thus, it is evident that the shell dynamic behavior can be affected by many parameters which characterize the reinforcing phase. A widespread parametric study is performed in order to show the natural frequency variation. The general theoretical model for shell structures is based on the so-called Carrera Unified Formulation (CUF) which allows to consider several Higher-order Shear Deformations Theories (HSDTs). In addition, a complete characterization of the mechanical properties of CNTs is presented. The governing equations for the free vibration analysis are solved numerically by means of the well-known Generalized Differential Quadrature (GDQ) method due to its accuracy, stability and reliability features.

Effect of agglomeration on the natural frequencies of functionally graded carbon nanotube-reinforced laminated composite doubly-curved shells

A review on optimization of composite structures Part I: Laminated composites

The static response of composite plates and shells reinforced by agglomerated nanoparticles made of Carbon Nanotubes (CNTs) is investigated in the present paper. A two-parameter agglomeration model is taken into account to describe the micromechanics of such particles, which show the tendency to agglomerate into spherical regions when scattered in a polymer matrix. From the macro mechanical point of view, the structures under consideration are characterized by a gradual variation of their mechanical properties along the thickness direction, since various distributions are employed to describe the volume fraction of the reinforcing phase. Several Higher-order Shear Deformation Theories (HSDTs) are taken into account and compared. The fundamental equations which govern the static problem in hand are solved numerically by means of the Generalized Differential Quadrature (GDQ) method. The variation of the agglomeration parameters, as well as the through-the-thickness profiles which describe the CNT volume fraction, are investigated to show the effect of the reinforcing phase on the static response of these nanocomposite plates and shells. In particular, a posteriori stress and strain recovery procedure is developed for these purposes. The current approach is validated through the comparison with the results available in the literature or obtained by a three-dimensional finite element model.

Linear static response of nanocomposite plates and shells reinforced by agglomerated carbon nanotubes

Vibration analysis of variable thickness plates and shells by the Generalized Differential Quadrature method

A review of the literature reveals that information regarding fundamental frequencies and mode shapes of shallow laminated composite hypar shells with practical civil engineering boundary conditions is not available. The present investigation aims to fill this gap by applying an eight-noded isoparametric shell element as the tool. Numerical experiments are carried out for different parametric variations including boundary conditions and stacking orders to obtain the fundamental frequencies and mode shapes. Some of the results are used for validating the correctness of the present approach by comparing with the existing benchmark, while the other results are studied meticulously to extract a set of meaningful conclusions regarding the free vibration characteristics of composite shallow hypar shells.

FiniteElement Vibration Characteristics of Composite Hypar Shallow Shells with Various Edge Supports

Abstract In this paper free vibration behavior of laminated composite stiffened elliptic parabolic shell has been analyzed in terms of natural frequency and mode shape. Finite element method has been applied using an eight-noded curved quadratic isoparametric element for shell with a three noded curved beam element for stiffener. Cross and angle ply shells with different edge conditions have been studied varying the size and position of the cutouts to arrive at a set of inferences of practical engineering significances.

/pdf/free-vibration-behavior-of-laminated-composite-stiffened-3xduk6vvoh.pdf

Free vibration behavior of laminated composite stiffened elliptic parabolic shell panel with cutout

Stiffened composite hypar shell roofs under free vibration: Behaviour and optimization aids

A general finite element procedure with an eight-noded isoparametric curved quadratic element is presented to investigate the static behaviour of laminated composite hyperbolic paraboloidal shells bounded by straight edges (commonly called hypar shells). Numerical results are obtained for uniformly loaded laminated composite hypar shells with six practical boundary conditions, where the edges are differently restrained. Eight different types of lamination including single layered and multi-layered, cross-ply and angle-ply, symmetric and antisymmetric stacking orders are chosen. The numerical results of different shell actions of 48 combinations are furnished to estimate their relative performances. The authors further propose typical comparative performance matrix to study the relative efficiencies of different stacking combinations, which will be a great help in design.

Sarmila Sahoo

Papers

FiniteElement Vibration Characteristics of Composite Hypar Shallow Shells with Various Edge Supports

Free vibration behavior of laminated composite stiffened elliptic parabolic shell panel with cutout

Stiffened composite hypar shell roofs under free vibration: Behaviour and optimization aids

Finite element bending behaviour of composite hyperbolic paraboloidal shells with various edge conditions

Laminated composite stiffened shallow spherical panels with cutouts under free vibration – A finite element approach