Papers by Keyword: Composite Shell

Abstract: Commercial production of synthetic resin has begun at the beginning of the XX century. In 1950s in the USA, small-span dome roofs, scanner assemblies and spherical hangars for radars made of plastic began to appear. Later, invention of reinforced plastics gave a possibility to use them in thin-walled shells for civil and industrial buildings. The subject of the paper associates with today’s renewed interest in thin shells. The modern theoretical base of strength analyses of composite structures give a possibility to design different structures and buildings. The possibility of the application of composites as the basic elements of thin-walled shell structures of industrial and civil purpose are illustrated by the concrete examples. The paper presents information on the well-known composite shells of positive Gaussian curvature in the form of spherical and umbrella domes or with more complex middle surfaces and presents materials that are absent in other publications. The paper contains 9 figures and 15 references.

Abstract: Asymmetric meshing is a perturbation introduced in the numerical model without changing geometry, loading or boundary conditions. Asymmetric meshing is employed in the form of a band along axial direction of the shell model, the elements size in the axial band is reduced as compared with the rest of shell to produce asymmetry in the meshing and four amplitudes of asymmetry are used in a particular band. Asymmetric meshing affects predicted buckling load, buckling mode shape and post-buckling behaviour. The reduction in the buckling load using asymmetric meshing was observed to be about 18%, which depends mainly on area of asymmetric meshing and less on different magnitudes of asymmetry in the same area. The load-displacement curve behaviourusing asymmetric meshing technique is quite similar to the curve obtained by introducing geometric imperfection in the shell model.

Abstract: In this study, the evolution of laminates in four damages are analyzed based on the established multiscale reinforced composite material damage model from a single cell model, single plate model to multilayer fiber model of carbon fiber. The validity of the model is verified by numerical simulation of laminate tensile test. Based on the established model to calculate the [±26/90₂]₃ damage evolution of SRM due to withstand pressure in the straight section and the results show that: the calculation is consistent with the experimental results of displacement, and the role of a variety of common damages result in reduced performance of the housing.

Abstract: This paper encompasses the work from numerical model by investigating the compression response of CFRP composite cylinder shells. The aim of this paper is to improve the reliability of NASA SP-8007 design guideline. The cylinder geometrical imperfections were tested through numerical modelling and validate with the experiment results. Good results comparison has been obtained through the work with small amount of errors. The cylinder shell load carrying capacity has been improved by average of 56% through imperfection study. This work builds confidence in the future use of non-linear finite element for the design of composite cylinder subjected to axial compression load.

Abstract: Results from Finite Element (FE) study on the response of composite cylinder shells with cutouts and subjected to internal pressure and axial compression are presented. The objective of the study is to improving the buckling load by applying the internal pressure whilst the compression load is applied. The effect of localized stress concentration distributed around the cutout region also being examined. The numerical results are obtained using ABAQUS finite element code software package. The composite cylinder shells were tested in two conditions which are a combination of axial compression load with internal pressure and a single axial compression load. The effects of varying internal pressure and cutout size on the pre-buckling, buckling, and post-buckling responses of the shell are demonstrated. Reasonable results comparison was obtained by reviewing previous literature. Results indicated that the load distribution and displacement of the cutout significantly influence the structural response of the shell. The results also indicate that the stress distributions can be affected by the size of the cutout under axial compression load.

Abstract: Elasticity solution is presented for simply-supported, orthotropic, piezoelectric cylindrical shell with finite length under local ring load in the middle of shell and electrostatic excitation. The highly coupled partial differential equations (p.d.e.) are reduced to ordinary differential equations(o.d.e.) with variable coefficients by means of trigonometric function expansion in longitudinal direction for displacement and external forces. The resulting ordinary differential equations are solved by Galerkin finite element method. Numerical examples are presented for [0/90/P] lamination with sensor and actuator for different thicknesses.

Abstract: This work deals with fundamental frequency optimization in Multi-Layered laminated composite cylindrical shell which is subjected to strength failure criteria (Tsai-Hill) constraint. Anisotropic cylindrical shell has finite length with simply supported conditions at both ends. Three dimensional elasticity approaches is used to obtain the objective functioin. To perform optimization, genetic algorithms (GAs) have been used. But GAs does not have the capability of constraint handling. In this paper penalty method as an auxiliary method for GAs has been used to take into accounts the constraints. Tsai-Hill criteria is used as failure constraint. Finally the results are presented for a multi-layered composite shell.

Abstract: In this paper a transient dynamic finite element analysis is presented to study the response of centrally impacted delaminated composite pretwisted cylindrical shells. An eight noded isoparametric plate bending element is employed in the finite element formulation. Effects of transverse shear deformation and rotary inertia are included. To satisfy the compatibility of deformation and equilibrium of resultant forces and moments at the delamination crack front a multipoint constraint algorithm is incorporated. The modified Hertzian contact law which accounts for permanent indentation is utilized to compute the contact force, and the time dependent equations are solved by Newmark’s time integration algorithm. Parametric studies are performed in respect of relative size of delamination and angle of twist for graphite-epoxy composite cylindrical shallow shells subjected to low velocity normal impact.