scholarly journals THEORETICAL STUDY ON BUCKLING OF DEEP WATER PIPELINE UNDER EXTERNAL HYDROSTATIC PRESSURE

2008 ◽  
Vol 64 (3) ◽  
pp. 588-602
Author(s):  
Jianhong WANG ◽  
Atsushi KOIZUMI
Keyword(s):  
Hydrostatic Pressure ◽  
Deep Water ◽  
Theoretical Study ◽  
External Hydrostatic Pressure ◽  
Water Pipeline

Deep Water Carcass Development: Effects of Carcass Profile on Collapse Resistance

2013 ◽  
Author(s):  
Jian Zhao ◽  
Zhimin Tan ◽  
Terry Sheldrake
Keyword(s):  
Hydrostatic Pressure ◽  
Deep Water ◽  
Element Model ◽  
Design Parameters ◽  
External Hydrostatic Pressure ◽  
Acceptance Criterion ◽  
Collapse Strength ◽  
Collapse Resistance ◽  
Flexible Pipes ◽  
Inclination Angles

The increasing application of flexible pipes in deep water requires extension of the product’s capability through higher design pressures with large diameters, while one of the most important structural capacities is collapse resistance. In addition to the introduction of new materials and manufacturing capability, the carcass structure is also expected to be optimized for maximum purpose. The carcass is an interlocked metallic construction that is used as the innermost layer to prevent for example, either totally or partially, the collapse of the internal pressure sheath due to decompression, or the pipe, due to external hydrostatic pressure, tensile armour pressure, and mechanical crushing loads. During manufacture of the carcass, its profile may differ from the nominal designed profiles and this may affect the collapse resistance. In this paper the effects of the carcass profile on the wet collapse strength of flexible pipes via numerical simulation are investigated. The wet collapse strength is referred to as the hydrostatic collapse strength of the pipe when the annulus is assumed to be flooded with seawater. In this condition, the external hydrostatic pressure acts directly on the barrier layer above the carcass. Using ANSYS, a 3D finite element model with the consideration of helical effects and cyclic boundary condition, which was developed to check the effect of each part of the carcass profile on the collapse strength by varying the design parameters, e.g. inclination angles, etc, and manufacturing ovality. As both verification and comparison, the principle of the effects is explored and explained analytically. The results can be used as an acceptance criterion on the as-built profiles in the manufacturing process, and as a guideline for the innovation and optimization of the carcass for maximum performance.

Study of Ductile-to-Brittle Transition in Single Grit Diamond Scribing of Silicon: Application to Wire Sawing of Silicon Wafers

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Hao Wu ◽  
Shreyes N. Melkote
Keyword(s):  
Hydrostatic Pressure ◽  
Silicon Wafers ◽  
Depth Of Cut ◽  
Critical Depth ◽  
External Hydrostatic Pressure ◽  
Tensile Stresses ◽  
Brittle Transition ◽  
Ductile Mode Cutting ◽  
Critical Depth Of Cut ◽  
Ductile To Brittle Transition

The ductile-to-brittle cutting mode transition in single grit diamond scribing of monocrystalline silicon is investigated in this paper. Specifically, the effects of scriber tip geometry, coefficient of friction, and external hydrostatic pressure on the critical depth of cut associated with ductile-to-brittle transition and crack generation are studied via an eXtended Finite Element Method (XFEM) based model, which is experimentally validated. Scribers with a large tip radius are shown to produce lower tensile stresses and a larger critical depth of cut compared with scribers with a sharp tip. Spherical tipped scribers are shown to generate only surface cracks, while sharp tipped scribers (conical, Berkovich and Vickers) are found to create large subsurface tensile stresses, which can lead to nucleation of subsurface median/lateral cracks. Lowering the friction coefficient tends to increase the critical depth of cut and hence the extent of ductile mode cutting. The results also show that larger critical depth of cut can be obtained under external hydrostatic pressure. This knowledge is expected to be useful in optimizing the design and application of the diamond coated wire employed in fixed abrasive diamond wire sawing of photovoltaic silicon wafers.

Deep Water Pipeline Repair In The Gulf Of Mexico

2014 ◽  
Author(s):  
Lance Brown ◽  
Adrian Dayani ◽  
Shaun Lazenby ◽  
Jackson Miller
Keyword(s):  
Gulf Of Mexico ◽  
Deep Water ◽  
Water Pipeline

scholarly journals OPTIMUM BUCKLING DESIGN OF CYLINDRICAL STIFFENER SHELL UNDER EXTERNAL HYDROSTATIC PRESSURE

2018 ◽  
Vol 18 (2) ◽  
pp. 239-252 ◽  
Author(s):  
Rawa Hamed M. Al-Kalali
Keyword(s):  
Hydrostatic Pressure ◽  
Numerical Optimization ◽  
Collapse Load ◽  
Ansys Software ◽  
External Hydrostatic Pressure ◽  
Buckling Mode ◽  
Design Elements ◽  
Design Variables ◽  
Thick Cylinder ◽  
Strength Constraints

This paper present an investigation of the collapse load in cylinder shell under uniformexternal hydrostatic pressure with optimum design using finite element method viaANSYS software. Twenty cases are studied inclusive stiffeners in longitudinal and ringstiffeners. Buckling mode shape is evaluated. This paper studied the optimum designgenerated by ANSYS for thick cylinder with external hydrostatic pressure. The primarygoal of this paper was to identify the improvement in the design of cylindrical shell underhydrostatic pressure with and without Stiffeners (longitudinal and ring) with incorporativetechnique of an optimization into ANSYS software. The design elements in this researchwas: critical load, design variable (thickness of shell (TH), stiffener’s width (B) andstiffener’s height (HF). The results obtained illustrated that the objective is minimizedusing technique of numerical optimization in ANSYS with optimum shell thickness andstiffener’s sizes. In all cases the design variables (thickness of shell) was thicker than themonocoque due to a shell’s thicker is essential to achieve the strength constraints. It can beconcluded that cases (17,18,19, and 20) have more than 90% of un-stiffened critical load.The ring stiffeners causes increasing buckling load than un-stiffened and longitudinalstiffened cylinder.

Plastic buckling of ring-stiffened conical shells under external hydrostatic pressure

2005 ◽  
Vol 32 (1) ◽  
pp. 21-36 ◽  
Author(s):  
Carl T.F. Ross ◽  
Andrew P.F. Little ◽  
Kehinde A. Adeniyi
Keyword(s):  
Hydrostatic Pressure ◽  
External Hydrostatic Pressure ◽  
Plastic Buckling ◽  
Conical Shells
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