Mechanical behavior of GFRP laminated composite pipe subjected to uniform radial patch load

Cylindrical vessels are widely used for storage and transportation of fluids. Using composites shells can improve the corrosion resistance of the product and reduce weight therefore investigation of the mechanical behavior is important. For this purpose cylinders with 6, 12 and18-ply of GFRP , with symmetric ply sequence of [90/0/90]s, [90/0/90/0/90/0]s and, [90/0/90/0/90/0/90 /0/90]s with layer thickness 1.3 mm and mean radius 250 mm, are considered under uniform radial patch load. The analysis was based on the shell theory and classical mechanics of laminated composites. A code was written using MATLAB software to compute stress and deflection of the cylinder shell. In numerical simulation, each unidirectional composite ply is treated as an equivalent elastic and orthotropic panel. Analysis is focused on the area of cylinder where the patch load is applied. The results show that the analytical prediction compares well with numerical responses of previous literature. The procedure can be used to predict maximum stress and displacement in a multi-layer shell for various types of similar loading

Mechanical response of laminated composite cylindrical shell subjected to radial patch loading

Due to significant amount of applications in industries, composite materials and structures are subjected to many different types of loading. One of the most common types of these loading is radial patch loading. Due to the complexity, calculation of radial shell deflection is the main character of the cylinder behavior when subjected to patch loading. The aim of this study is to investigate the mechanical behavior of composite cylindrical shell subjected to radial patch loading. The radial deflection of the laminated shell is investigated in detail where analytical and finite element methods (FEM) are used. The results through both approaches are compared to validate the accuracy of the analytical method. This is followed by a parametric study to determine the effect of some operation parameters on radial displacement. The results show close agreement between the analytical and numerical methods

Mechanical behavior of composite plate under combined impact and internal pressure

This research presents results obtained from numerical analysis of a circular composite plate under impact of drop hammer and internal pressure load simultaneously. Influence of reinforced orientationangles of the multi-layer composite plate with fixed boundary conditions on displacements and axial stresses along the radius direction was studied. Employing ABAQUS software results for reinforcedorientation angles of [0/90/0]s, [0/45/60]s, [0/45/90]s, [0/30/60]s, [0/30/75]s, [0/15/30/60/75/90],[0/45/90/90/-45/0] are compared. Finding indicated that the reinforcedorientation angles have considerable effect on the axial stresses changing from compressive to tensile stresses. [0/45/90/90/-45/0]s showed the minimum displacements and axial stresses

Tensile test machine for unsymmetrical materials

A novel solution to overcome the shortcoming of conventional tensile test machines in dealing with unsymmetrical materials and off-axis testing of composites is presented. Conventional testing machines are designed on the basis of subjecting a specimen to axial load to determine the stiffness and strength of the material. For specimens with unsymmetrical cross-section this method is no longer valid due to induced additional bending stresses. To overcome this problem a novel tensile test machine was designed, which allows bending deformation, thus subjecting the specimen to pure tension instead of axial loading. To validate the design, the machine was fabricated and employed for tensile testing of an aluminum specimen with unsymmetrical cross-section. The comparison of test results from a conventional machine and from analytically calculations, based on pure tension, reveals that conventional machine generates significant errors, while the results from new machine are in good agreement. The machine was then used to test a functionally graded beam

Effect of ply thickness on displacements and stresses in laminated GFRP cylinder subjected to radial load

The superior feature of composites such as high stiffness against low density have impelled engineers to use this material in automotive, aerospace and building industries. In the past few decades, composites shell has found applications in storage tanks and transmission pipelines. Designing laminated composite shells is challenging because of the complex mechanical behavior when combining laminate and shell theories. In this paper, the study is focused on the effect of lamina thickness on performance of the GFRP cylinder. For this purpose two 12-ply GFRP cylinders are considered with ply sequences of [0/90/45]s. The lamina thicknesses of the composite shell are assumed to be 0.1, 0.5, 1 and 1.5 mm, to evaluation of the mechanical behaviors of the cylinders and identifying one with the highest strength. The 250 mm diameter cylinders are subjected to a uniform radial patch load. A code is written for the solution based on the shell theory and classical mechanics of laminated composite using MATLAB software. The results are validated by comparing the present results with those found in literature. A good correlation justifies the study being extended to include the study on the effect of ply and shell thickness. The procedure is recommended for design and optimization for strength of various sizes of composite pipe

Thermo-mechanical behaviour of smart composite beam under quasi-static loading

Experimental and numerical studies on a hybrid composite smart beam under quasi-static loading were carried out. The composite beam is consisted of two layers; carbon fibre/epoxy and SMA wire/epoxy layer. Carbon fibres as well as SMA wires were embedded in the host epoxy unidirectionally. SMA wires were programmed before being embedded in the composite beam. All thermo-mechanical properties associated with SMA wires were experimentally determined. A constant flexural load was initially applied to the middle of a simply-supported beam and temperature of the beam was then increased. The beam was heated using a thermal-chamber. During the heating process the deflection of the beam at midpoint was measured and the behaviour of the hybrid beam under incremental load was investigated. It was observed that, the presence of embedded SMA wires in the beam can effectively reduce deflection. Furthermore, using high volume fraction of fibres can cause buckling in the opposite direction of lateral force. Experimental results were compared against FE method and a perfect fit was obtained

Flexural behavior of functionally graded slender beams with complex cross-section

Deflection and stress analyses of functionally graded beams with complex cross-section and general material variation, under transverse loading, were carried out. The elastic-fundamental solution is used to derive equations satisfied by the normal stresses in arbitrary cross-sections of the beam, assuming that the plane sections remain plane and normal to the beam axis. The technique was verified by existing analytical and finite element models. Numerical experiments were then performed where the material properties vary through thickness or width of the beams according to power-law and exponential gradations. It was found that the quality of material gradation affects the deflection, stresses and neutral axis position significantly. It is concluded that the technique is useful for the elastic behavior analysis of FGBs with complex cross-sections and various material gradation

Static analysis of stitched sandwich beams with functionally graded foam core

In this paper static analysis of a cantilever functionally graded sandwich beam under uniform distributed loads is carried out numerically. The beam is composed of two glass fiber reinforced plastic (GFRP) facesheets and a graded Corecell A-series foam core. The composite skins and foam core are stitched together using the same glass fiber. A finite element (FE) model is developed employing a FE commercial code to determine the stresses and deflections. To find the effect of quality of foam gradation through the thickness of the core on the deflections and stresses numerical experiments are performed. Results revealed that the quality of gradation of the foam core affected the displacements and stresses significantly so that an optimal gradation of foam can minimize the deflection, stresses and weight of the sandwich beam