Decay Length in Pressure Vessels

2017 ◽  
Author(s):  
R. Adibi-Asl ◽  
R. Seshadri
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Edge Effect ◽  
Interaction Effects ◽  
Pressure Vessels ◽  
Decay Length ◽  
Internal Edge ◽  
Element Analysis ◽  
Conical Shells

In theory of shell, decay length is defined as the distance affected by localized external (applied loads) or internal (edge effect, discontinuity) forces and moments, beyond which the effect of these loads becomes negligible. The concept of decay length becomes relevant when assessing the interaction effects caused by adjacent discontinuities. In this paper, the decay lengths for several shells geometries, specifically cylindrical, spherical and conical shells, are reviewed. The available expressions for decay lengths in the literature are listed and are compared with finite element analysis to demonstrate the accuracy of some of the solutions.

scholarly journals Tentative Investigations on Reducing the Edge Effects in Pre-Polishing the Optics

2020 ◽  
Vol 10 (15) ◽  
pp. 5286
Author(s):  
Xiaolong Ke ◽  
Lei Qiu ◽  
Chunjin Wang ◽  
Zhenzhong Wang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Edge Effect ◽  
Edge Effects ◽  
Material Removal ◽  
Processing Time ◽  
Grinding Process ◽  
Element Analysis ◽  
Edge Zone ◽  
The Finite Element Analysis

The material removal depth in the pre-polishing stage of the precision optics is usually tens of microns to remove the subsurface damage and grinding marks left by the previous grinding process. This processing of the upstand edge takes a large part of the time at this stage. The purpose of this paper is to develop a method that can reduce the edge effect and largely shorten the processing time of the pre-polishing stage adopting the semirigid (SR) bonnet. The generation of the edge effect is presented based on the finite element analysis of the contact pressure at the edge zone firstly. Then, some experimentations on the edge effect are conducted, and the results proved that the SR bonnet tool can overhang the workpiece edge in the pre-polishing stage to reduce the width and height of the upstand edge to largely shorten the subsequent processing time of it. In addition, there exists a perfect overhang ratio, which generates the upstand edge with the smallest width and height, with no damage to the bonnet tool in the meantime. In addition, one combination of the pre-polishing parameters is concluded according to this method, which can be safely adopted in practical process.

Stress Analysis and Structure Optimization for the Opening Flat Cover of Pressure Vessels

2012 ◽  
Vol 538-541 ◽  
pp. 3253-3258 ◽  
Author(s):  
Jun Jian Xiao
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Stress Analysis ◽  
Structure Optimization ◽  
Pressure Vessels ◽  
Secondary Stress ◽  
Element Analysis ◽  
Primary Stress ◽  
Flat Cover

According to the results of finite element analysis (FEA), when the diameter of opening of the flat cover is no more than 0.5D (d≤0.5D), there is obvious stress concentration at the edge of opening, but only existed within the region of 2d. Increasing the thickness of flat covers could not relieve the stress concentration at the edge of opening. It is recommended that reinforcing element being installed within the region of 2d should be used. When the diameter of openings is larger than 0.5D (d>0.5D), conical or round angle transitions could be employed at connecting location, with which the edge stress decreased remarkably. However, the primary stress plus the secondary stress would be valued by 3[σ].

Maximum Stress at Intersecting Bores of Pressurized Blocks

1994 ◽  
Author(s):  
Ajay Garg
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Tensile Stress ◽  
Element Model ◽  
Maximum Tensile Stress ◽  
Pressure Vessels ◽  
Experimental Results ◽  
Empirical Methods ◽  
Element Analysis ◽  
Matched Design

Abstract In high pressure applications, rectangular blocks of steel are used instead of cylinders as pressure vessels. Bores are drilled in these blocks for fluid flow. Intersecting bores with axes normal to each other and of almost equal diameters, produce stresses which can be many times higher than the internal pressure. Experimental results for the magnitude of maximum tensile stress along the intersection contour were available. A parametric finite element model simulated the experimental set up, followed by correlation between finite element analysis and experimental results. Finally, empirical methods are applied to generate models for the maximum tensile stress σ11 at cross bores of open and close ended blocks. Results from finite element analysis and empirical methods are further matched. Design optimization of cross bores is discussed.

Finite element analysis for optimal design of fuel cell pressure vessels

2020 ◽  
Vol 2020.28 (0) ◽  
pp. 104
Author(s):  
Riku SUZUKI ◽  
Noboru KATAYAMA ◽  
Kiyoshi DOWAKI ◽  
Shinji OGIHARA
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fuel Cell ◽  
Optimal Design ◽  
Pressure Vessels ◽  
Element Analysis

Finite Element Analysis of Local Inelastic Strain Based on Stress Redistribution Locus

2008 ◽  
Author(s):  
Shunji Kataoka ◽  
Takuya Sato
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Loading ◽  
Failure Modes ◽  
Elevated Temperatures ◽  
Pressure Vessels ◽  
Stress Redistribution ◽  
Strain Diagram ◽  
Element Analysis ◽  
Inelastic Analysis

Creep-fatigue damage is one of the dominant failure modes for pressure vessels and piping used at elevated temperatures. In the design of these components the inelastic behavior should be estimated accurately. An inelastic finite element analysis is sometimes employed to predict the creep behavior. However, this analysis needs complicated procedures and many data that depend on the material. Therefore the design is often based on a simplified inelastic analysis based on the elastic analysis result, as described in current design codes. A new, simplified method, named, Stress Redistribution Locus (SRL) method, was proposed in order to simplify the analysis procedure and obtain reasonable results. This method utilizes a unique estimation curve in a normalized stress-strain diagram which can be drawn regardless of the magnitude of thermal loading and constitutive equations of the materials. However, the mechanism of SRL has not been fully investigated. This paper presents results of the parametric inelastic finite element analyses performed in order to investigate the mechanism of SRL around a structural discontinuity, like a shell-skirt intersection, subjected to combined secondary bending stress and peak stress. This investigation showed that SRL comprises a redistribution of the peak and secondary stress components and that although these two components exhibit independent redistribution behavior, they are related to each other.

Study on the Stress Concentration at the Round Corners of Flat Heads in Pressure Vessels Subjected to Internal Pressure

1996 ◽  
Vol 118 (4) ◽  
pp. 429-433
Author(s):  
H. Chen ◽  
J. Jin ◽  
J. Yu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Intensity ◽  
Stress Concentration ◽  
Internal Pressure ◽  
Pressure Vessel ◽  
Pressure Vessels ◽  
Stress Index ◽  
Element Analysis ◽  
Approximate Formulas

Results from finite element analysis were used to show that the stress index kσ and the nondimensionalized highly stressed hub length kh of a flat head with a round corner in a pressure vessel subjected to internal pressure are functions of three dimensionless parameters: λ ≡ h/dt, η ≡ t/d, and ρ ≡ r/t. Approximate formulas for estimating kσ and kh from λ, η, and ρ p are given. The formulas can be used for determining a suitable fillet radius for a flat head in order to reduce the fabricating cost and to keep the stress intensity at the fillet under an acceptable limit.

Investigation of interlayer hybridization effect on burst pressure performance of composite overwrapped pressure vessels with load-sharing metallic liner

2019 ◽  
Vol 54 (7) ◽  
pp. 961-980 ◽  
Author(s):  
Serkan Kangal ◽  
Osman Kartav ◽  
Metin Tanoğlu ◽  
Engin Aktaş ◽  
H Seçil Artem
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Glass Fibers ◽  
Load Sharing ◽  
Pressure Vessels ◽  
Filament Winding ◽  
Burst Pressure ◽  
Element Analysis ◽  
Metallic Liner ◽  
Numerical Approaches

In this study, multi-layered composite overwrapped pressure vessels for high-pressure gaseous storage were designed, modeled by finite element method and manufactured by filament winding technique. 34CrMo4 steel was selected as a load-sharing metallic liner. Glass and carbon filaments were overwrapped on the liner with a winding angle of [±11°/90°2]3 to obtain fully overwrapped composite reinforced vessel with non-identical front and back dome endings. The vessels were loaded with increasing internal pressure up to the burst pressure level. The mechanical performances of pressure vessels, (i) fully overwrapped with glass fibers and (ii) with additional two carbon hoop layers on the cylindrical section, were investigated by both experimental and numerical approaches. In numerical approaches, finite element analysis was performed featuring a simple progressive damage model available in ANSYS software package for the composite section. The metal liner was modeled as elastic–plastic material. The results reveal that the finite element model provides a good correlation between experimental and numerical strain results for the vessels, together with the indication of the positive effect on radial deformation of the COPVs due to the composite interlayer hybridization. The constructed model was also able to predict experimental burst pressures within a range of 8%. However, the experimental and finite element analysis results showed that hybridization of hoop layers did not have any significant impact on the burst pressure performance of the vessels. This finding was attributed to the change of load-sharing capacity of composite layers due to the stiffness difference of carbon and glass fibers.

Analysis of a Hemispherical Head With Nozzle and Local Thin Area

2004 ◽  
Author(s):  
Michael W. Guillot ◽  
Jack E. Helms
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pressure Vessels ◽  
Structural Defects ◽  
Finite Element Models ◽  
Finite Element Analyses ◽  
Element Analysis

The ability to analyze the behavior of pressure vessels with structural defects has been greatly improved by the general availability of PC based finite element analysis programs. In this study a hemispherical head with a nozzle and a local thin area is analyzed using finite element models. The requirement to apply a 15 % stress adjustment is also examined in light of the results of the finite element analyses.

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