Papers by Keyword: Shell Theory

Abstract: In this paper, a hollow square cross-section carbon fiber/epoxy composite beam was designed and manufactured. Evaluation of the beam behavior considered orientation and stacking sequence, aiming to reduce the number of layers and weight. Finite element method (FEM) was used to simulate the performance of the composite beam under 3-point bending and using three failure criteria, Tsai-Hill, Tsai-Wu and maximum stress. In order to identify the input parameters for the model, flat composites were tested under tension and compression. It was concluded that a minimum of 12 layers of unidirectional carbon fiber were required to reach the required load (44.5 kN). The prototype was successfully fabricated by vacuum-infusion process and subjected to 3-point bending test. The experimental failure load was within the predicted range by the Tsai-Hill failure criteria and maximum stress.

Abstract: 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.

Abstract: Top drive casing running tool, because of its convenience, speed and safety, has been widely received by the research enterprises of petroleum mechanism and instrument. Now, there have been developed several kinds of casing running tools which have gradually been used by the drilling corporation at home and abroad. The slips system’s parameters, such as the axial thrust, slips length, teeth form, teeth interval, etc., directly affect the performance and safety of casing running tools. Those have no reports about correlative theoretical investigation results. Here, we found the mechanical analysis model between slip and casing and gain the minimum primitive axis thrust of slips. Then the minimum teeth interval of the slips is deduced by contact mechanics. And then the slips available working length is worked out through the shell theory and empirical formulas. Finally, based on finite element method, we obtain tooth form angles’ recommendable range by studying the tooth form. This study supplies theoretical basis to structural design of slips system of the top drive casing running tool.