E.V. Morozov

Thin-Walled Composite Beams

The thin-walled composite beam model is widely used to simulate the behavior of engineering structural elements. The thin-walled beam is actually a cylindrical shell whose length is much greater than the dimensions of the cross section which, in turn, are much greater than the thickness of the wall. These specific features of thin-walled beams allow us to introduce a system of assumptions which, in turn, enables us to develop a relatively simple and efficient applied theory and to reduce the two-dimensional equations of shell theory to ordinary differential equations providing, as a rule, closed-form analytical solutions.

Chapter 9 – Laminated composite plates

Laminated composite plates possessing high strength and stiffness under in-plane loading and bending are widely used nowadays in composite aircraft and marine structures and have been discussed by many authors. This chapter is concerned with traditional and advanced specific problems and applications of the theory of anisotropic plates. We consider mainly balanced and symmetrically laminated orthotropic plates, but plates with more complicated structures are discussed in some sections of this chapter.

Vibration-based delamination detection in composite beams through frequency changes

Delamination is a common damage in fibre reinforced composite laminates, usually hidden from external view, that can substantially reduce the structural stiffness which changes the dynamic response of the structures such as natural frequencies. Natural frequencies are the most reliable parameters for detecting damage while they do not directly provide information regarding its location and severity. To determine the location and severity of damage, it is necessary to solve the inverse problem using frequency shifts in multiple modes. In this paper, the graphical approach, which was previously employed for estimating two variables of crack (location and size) in isotropic beams, is extended in the current work to estimate the three variables of delamination (interface, span-wise location and size) in anisotropic composite beams from measured frequency shifts. Compared to the use of optimisation or neural network for detection, graphical technique is computationally inexpensive and quick since it solves the inverse problem without iterations or network training. The present approach has been validated using numerical simulation as well as experimental data from modal testing conducted on quasi-isotropic simply supported and cantilever beams. Results show that the proposed graphical technique can be used to assess the location and severity of delamination in composite beams with a high degree of accuracy.

Fundamental Frequency of Fully Clamped Composite Sandwich Plate

The magnitude of the first natural frequency is often used as a criterion of the design efficiency of sandwich panels. The vibrations of fully clamped sandwich plate are analyzed using Galerkin method. The effects of the panel dimensions, elastic properties and densities of the facings, and core on the fundamental frequency have been studied using the numerical solution, analytical approach, and finite element analysis. It follows from the analysis that the first natural frequency can be calculated with sufficient accuracy on the basis of the analytical solution developed in this work.

Experimental, Theoretical and Numerical Investigation of the Flexural Behaviour of the Composite Sandwich Panels with PVC Foam Core

This study presents the main results of an experimental, theoretical and numerical investigation on the flexural behaviour and failure mode of composite sandwich panels primarily developed for marine applications. The face sheets of the sandwich panels are made up of glass fibre reinforced polymer (GFRP), while polyvinylchloride (PVC) foam was used as core material. Four-point bending test was carried out to investigate the flexural behaviour of the sandwich panel under quasi static load. The finite element (FE) analysis taking into account the cohesive nature of the skin-core interaction as well as the geometry and materials nonlinearity was performed, while a classical beam theory was used to estimate the flexural response. Although the FE results accurately represented the initial and post yield flexural response, the theoretical one restricted to the initial response of the sandwich panel due to the linearity assumptions. Core shear failure associate with skin-core debonding close to the loading points was the dominant failure mode observed experimentally and validated numerically and theoretically.

Theoretical and experimental analysis of the deformability of filament wound composite shells under axial compressive loading

Abstract The numerical and experimental stress–strain analysis of the filament wound composite shells of revolution is presented. The computations are based on the refined theory of shells that allows for the transverse shear strain. The finite difference approximation was implemented to obtain the numerical solution of the problem. Parameters of the algorithm were determined from the computational experimentation. To verify the numerical procedure the parallel analysis was performed using the membrane theory of shells. The results of the mechanical tests performed on the composite shells loaded by axial compression are compared with the theoretical strain distributions over the shell length. Satisfactory agreement between the experimental data and the results of calculations demonstrated the viability and the accuracy of the proposed approach and model.

Tailoring of Composite Reinforcements for Weight Reduction of Offshore Production Risers

The use of composite materials in offshore engineering for deep sea oil production riser systems would lead to weight savings and improvement in fatigue and corrosion resistance. This paper examines the weight saving potentials offered by varying fibre orientations, stacking sequences, fibre matrix combinations and liner materials for deep sea riser tubulars. Four main load cases, recommended by design standards for the local design of composite offshore risers, are considered in the analysis using three-dimensional finite element modelling: maximum internal pressure, axial tension, top tension with external pressure and maximum external pressure.

Buckling analysis and design of a uniformly compressed rectangular composite sandwich plate with two parallel simply supported edges and another two edges clamped

The solution of the buckling problem for a rectangular composite sandwich plate with two parallel simply supported edges and another two edges clamped (SSCC) is presented in the paper. The plate is composed of two identical composite facings and orthotropic core, and subjected to in-plane uniform compressive load applied to the simply supported edges. Buckling equations are derived based on the first-order shear deformation theory. The problem is solved using the Levy and Galerkin methods. The analytical formula for the critical load has been obtained and verified using finite-element analysis. The design analyses have been performed for the sandwich panels subject to constraints imposed on the value of buckling load.

Flexure analysis of spoolable reinforced thermoplastic pipes for offshore oil and gas applications

This article is concerned with the numerical modelling and analysis of the mechanical behaviour of composite pipes used for offshore oil and gas applications. Specifically, the bending of the reinforced thermoplastic pipes during the reeling process of reel-lay installation is modelled using non-linear finite-element procedures. In particular, the possible buckling of the reeled composite pipes has been investigated. Composite pipes reinforced with one angle-ply and two angle-ply layers are considered and the effects of different diameter-to-thickness ratios and different angle-ply combinations on the mechanical behaviour of these pipes have been studied.

Symmetrical vibration modes of composite sandwich plates

This article is concerned with the modeling and analysis of symmetrical vibrations of composite sandwich panels. The vibration problem is solved for the sandwich plate with identical composite facings and orthotropic core. The solution is based on the use of the model that takes into account compressive and shear stiffnesses, and nonlinear distribution of transverse normal displacements over the core thickness. The equation is obtained for the calculation of symmetric vibration frequency of the sandwich plate with simply supported facings. The effects of elastic, geometric, and inertia parameters on the frequencies of symmetric vibrations are investigated.