The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
Stelios Kyriakides - One of the best experts on this subject based on the ideXlab platform.
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inelastic wrinkling and collapse of tubes under combined bending and Internal Pressure
International Journal of Mechanical Sciences, 2010Co-Authors: A Limam, Edmundo Corona, L H Lee, Stelios KyriakidesAbstract:Abstract The problem of inelastic bending and collapse of tubes in the presence of Internal Pressure is investigated using experiments and analyses. The experiments involve 1.5-inch diameter, D/t=52 stainless steel tubes bent to failure at fixed values of Pressure. The moment–curvature response is governed by the inelastic characteristics of the material. Bending induces some ovalization to the tube cross section while, simultaneously, the Internal Pressure causes the circumference to grow. Following some inelastic deformation, small amplitude axial wrinkles appear on the compressed side of the tube, and their amplitude grows stably as bending progresses. Eventually, wrinkling localizes, causing catastrophic failure usually in the form of an outward bulge. Internal Pressure stabilizes the structure, it increases the wavelength of the wrinkles and can increase significantly the curvature at collapse. The onset of wrinkling is established by a custom bifurcation buckling formulation. The evolution of wrinkling and its eventual localization are simulated successfully using a FE shell model. The material is represented as an anisotropic elastic–plastic solid using the flow theory, while the models are assigned initial geometric imperfections with the wavelength of the wrinkling bifurcation mode. It is demonstrated that successful prediction of collapse requires very accurate representation of the material inelastic properties including yield anisotropies, and that as expected, the collapse curvature is sensitive to the imperfection amplitude and wavelength imposed.
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Combined Internal Pressure and Axial Compression
Mechanics of Offshore Pipelines, 2007Co-Authors: Stelios Kyriakides, Edmundo CoronaAbstract:The inelastic response, as well as the limit state of long cylinders compressed in the presence of Internal Pressure, is similar to that of cylinders loaded under pure compression. The Internal Pressure interacts plastically with axial compression. For compression under a fixed Internal Pressure, this interaction results in lowering of the axial stress-strain response. The J2-type plasticity with isotropic hardening or its anisotropic counterpart can adequately capture this interaction. At some plastic strain level, the cylinder develops uniform axisymmetric wrinkling. Under continued compression, the wrinkles grow stably, gradually reducing the axial rigidity of the structure. This reduction in axial rigidity eventually leads to limit-load instability. Beyond the limit load, deformation localizes. The limit load is designated as the limit state of the structure.
Stefane Lopes - One of the best experts on this subject based on the ideXlab platform.
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Finite deformations of an initially stressed cylindrical shell under Internal Pressure
International Journal of Mechanical Sciences, 2008Co-Authors: Paul Gonçalves, Djenane Pamplona, Stefane LopesAbstract:This paper investigates the large deformations of an extended thick cylindrical tube under Internal Pressure, with emphasis on the static nonlinear behavior and instabilities of the shell. Thick elastic tubes that undergo large elastic deformations under Internal Pressure can exhibit novel instabilities. After some deformation, part of the tube becomes highly deformed taking the form of a bulge, while the remainder appears almost unchanged. This local instability phenomenon corresponds to a limit point along the nonlinear equilibrium path. After the onset of these highly nonuniform deformations, the local bulge initially grows with a marked decrease in Internal Pressure while the rest of the tube unloads. First, a detailed experimental analysis is carried out involving different geometries and initial axial forces and the influence of the axial force and of the Internal Pressure on the critical Pressure is investigated. The shell used in the experiments is composed of an isotropic, homogeneous and hyperelastic rubber, which is modeled as a Mooney–Rivlin incompressible material, described by two elastic constants. These constants are obtained by comparing the experimental and numerical solutions for the shell under axial tension. The governing shell equations are solved numerically using the finite-element method, using the program ABAQUS. The experimental results are, as shown in the paper, in satisfactory agreement with the numerical analysis.
Peng Cheng - One of the best experts on this subject based on the ideXlab platform.
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Behavior of Flexible Pipe Subjected to Internal Pressure
Volume 5: Pipelines Risers and Subsea Systems, 2016Co-Authors: Shuai Yuan, Wei Dong Ruan, Peihua Han, Yong Bai, Peng ChengAbstract:The increasing use of flexible pipes in subsea with high Pressure/high temperature brings about much more challenges. Although there has been a simple prediction method for burst Pressure, a more comprehensive prediction of the ultimate strength of flexible pipe subjected to Internal Pressure is essential for the safe use of flexible pipe under complex environments in terms of different failure modes. In this paper, based on the principle of virtual work, a theoretical model for stresses and deformations of the pipe under the short-term Internal Pressure have been developed and the obtained results have been compared with the ones from the FEM which is used to simulate the pipe under increasing Internal Pressure using ABAQUS. And the mechanical properties of two kinds of armor layers have been studied comprehensively considering different boundary conditions. The results and FEA models can be useful for the design of flexible pipes. Finally, the failure prediction of a complete model is discussed.Copyright © 2016 by ASME
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burst capacity of reinforced thermoplastic pipe rtp under Internal Pressure
ASME 2011 30th International Conference on Ocean Offshore and Arctic Engineering, 2011Co-Authors: Peng Cheng, Mohd Fauzi Adaruddi, Mohd AshriAbstract:Being corrosion resistant, light weight, and easy to install at relatively low cost, Reinforced Thermoplastic Pipe (RTP) is now increasingly being used for offshore operations. RTP pipe in this study is mainly composed of three layers: a wound high strength fiber reinforced layer to improve the resistance of the pipe to Internal Pressure; a plastic inner layer to transport fluid; a plastic outer layer to protect the pipe. A precise calculation of the burst strength of RTP pipe will be useful for the safe use of RTP pipe’s Internal Pressure resistance. The Finite Element Analysis (FEA) method and mathematical analysis are employed to study the properties of pipe under Internal Pressure. The Finite Element Analysis method is used to simulating the pipe under increasing Internal Pressure using ABAQUS. The model is established with the conventional shell element, and the anisotropic property of plastic is also considered in the model. In the mathematical analysis, the reinforcement layer of the pipe is assumed to be anisotropic and other layers are assumed to be isotropic. Based on the three-dimensional (3D) anisotropic elasticity theory, an exact elastic solution for burst strength of the pipe under Internal Pressure has been studied. This paper focus on the calculation of RTP pipe’s burst strength, using mathematical approach and FEA approach, on the basis of elaborated study of RTP pipe’s failure process. Our results from mathematical and FE simulation agree each other for burst Pressure of the RTP pipe. Our FEA models are also compared with the experimental research in order to validate our FEA models.Copyright © 2011 by ASME
A Limam - One of the best experts on this subject based on the ideXlab platform.
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inelastic wrinkling and collapse of tubes under combined bending and Internal Pressure
International Journal of Mechanical Sciences, 2010Co-Authors: A Limam, Edmundo Corona, L H Lee, Stelios KyriakidesAbstract:Abstract The problem of inelastic bending and collapse of tubes in the presence of Internal Pressure is investigated using experiments and analyses. The experiments involve 1.5-inch diameter, D/t=52 stainless steel tubes bent to failure at fixed values of Pressure. The moment–curvature response is governed by the inelastic characteristics of the material. Bending induces some ovalization to the tube cross section while, simultaneously, the Internal Pressure causes the circumference to grow. Following some inelastic deformation, small amplitude axial wrinkles appear on the compressed side of the tube, and their amplitude grows stably as bending progresses. Eventually, wrinkling localizes, causing catastrophic failure usually in the form of an outward bulge. Internal Pressure stabilizes the structure, it increases the wavelength of the wrinkles and can increase significantly the curvature at collapse. The onset of wrinkling is established by a custom bifurcation buckling formulation. The evolution of wrinkling and its eventual localization are simulated successfully using a FE shell model. The material is represented as an anisotropic elastic–plastic solid using the flow theory, while the models are assigned initial geometric imperfections with the wavelength of the wrinkling bifurcation mode. It is demonstrated that successful prediction of collapse requires very accurate representation of the material inelastic properties including yield anisotropies, and that as expected, the collapse curvature is sensitive to the imperfection amplitude and wavelength imposed.
Paul Gonçalves - One of the best experts on this subject based on the ideXlab platform.
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Finite deformations of an initially stressed cylindrical shell under Internal Pressure
International Journal of Mechanical Sciences, 2008Co-Authors: Paul Gonçalves, Djenane Pamplona, Stefane LopesAbstract:This paper investigates the large deformations of an extended thick cylindrical tube under Internal Pressure, with emphasis on the static nonlinear behavior and instabilities of the shell. Thick elastic tubes that undergo large elastic deformations under Internal Pressure can exhibit novel instabilities. After some deformation, part of the tube becomes highly deformed taking the form of a bulge, while the remainder appears almost unchanged. This local instability phenomenon corresponds to a limit point along the nonlinear equilibrium path. After the onset of these highly nonuniform deformations, the local bulge initially grows with a marked decrease in Internal Pressure while the rest of the tube unloads. First, a detailed experimental analysis is carried out involving different geometries and initial axial forces and the influence of the axial force and of the Internal Pressure on the critical Pressure is investigated. The shell used in the experiments is composed of an isotropic, homogeneous and hyperelastic rubber, which is modeled as a Mooney–Rivlin incompressible material, described by two elastic constants. These constants are obtained by comparing the experimental and numerical solutions for the shell under axial tension. The governing shell equations are solved numerically using the finite-element method, using the program ABAQUS. The experimental results are, as shown in the paper, in satisfactory agreement with the numerical analysis.
