Analytical Investigations of Compact Reinforcement for Radial Nozzles in Spherical Shells

1971 ◽  
Vol 93 (4) ◽  
pp. 905-912 ◽  
Author(s):  
R. C. Gwaltney ◽  
J. M. Corum
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Experimental Results ◽  
Finite Element Analyses ◽  
Spherical Shells ◽  
Theoretical Predictions

Compact reinforcement for a series of models having single nozzles radially attached to spherical shells was examined by means of finite element analyses. Parameters studied were diameter-to-thickness ratios of the nozzles, diameter-to-thickness ratios of the spherical shells, percentage of reinforcement, outside reinforcement, inside reinforcement, and “balanced” reinforcement (reinforcement on both the inside and outside surfaces). The loading was internal pressure. Comparisons of theoretical predictions with experimental results are presented for one reinforced model. Twelve models were analyzed to examine the effect of compact reinforcement.

A Comparison of Theoretical and Experimental Results From Spherical Shells With a Single Radially Attached Nozzle

1967 ◽  
Vol 89 (3) ◽  
pp. 333-338 ◽  
Author(s):  
F. J. Witt ◽  
R. C. Gwaltney ◽  
R. L. Maxwell ◽  
R. W. Holland
Keyword(s):  
Spherical Shell ◽  
Internal Pressure ◽  
Experimental Results ◽  
Strain Gages ◽  
Spherical Shells ◽  
Axial Thrust ◽  
Outside Diameter ◽  
Theoretical Results

A series of steel models having single nozzles radially and nonradially attached to a spherical shell is presently being examined by means of strain gages. Parameters being studied are nozzle dimensions, length of internal nozzle protrusions, and angles of attachment. The loads are internal pressure and axial thrust and moment loadings on the nozzle. This paper presents both experimental and theoretical results from six of the configurations having radially attached nozzles for which the sphere dimensions are equal and the outside diameter of the attached nozzle is constant. In some instances the nozzle protrudes through the vessel.

Influence of backing materials towards the fatigue strength of butt-welded joints

2011 ◽  
Vol 225 (8) ◽  
pp. 1798-1807 ◽  
Author(s):  
M H Kim ◽  
H J Kim ◽  
J H Han ◽  
J M Lee ◽  
Y D Kim ◽  
...  
Keyword(s):  
Finite Element ◽  
Fatigue Strength ◽  
Welded Joints ◽  
Fatigue Tests ◽  
Experimental Results ◽  
Finite Element Analyses ◽  
Cold Metal Transfer ◽  
Notch Stress ◽  
Effective Notch Stress ◽  
Cold Metal

The purpose of this study is to investigate the fatigue strength of butt-welded joints with special attention paid to employing different kinds of backing plates. The effect of the under-matched weld was also considered. Four different cases of backing scenarios for butt-welded specimens such as steel backing, ceramic backing, CMT (no backing by cold metal transfer) and UM (under-matched welded specimen) were investigated. A series of fatigue tests was performed to compare the fatigue strength of butt-welded joints with respect to different backing scenarios. Effective notch stress was used for the interpretation of fatigue strength of butt-welded specimens with backing plates based on finite element analyses for calculating fatigue notch factors. When results were presented from the effective notch stress, all backing scenarios considered in this study exhibited the fatigue strengths corresponding to the FAT 225 curve. From the experimental results of this study, it was determined that the fatigue strengths of butt-welded joints were found to be in the order of CMT, ceramic backing, UM, and steel backing. No significant decrease in fatigue strength, however, was observed when backing plates were steel backing and ceramic backing types.

A Study of the Conservatism in ASME BPVC Section VIII Division 2 Opening Design for External Pressure

2019 ◽  
Author(s):  
Barry Millet ◽  
Kaveh Ebrahimi ◽  
James Lu ◽  
Kenneth Kirkpatrick ◽  
Bryan Mosher
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Pressure Vessel ◽  
External Pressure ◽  
The Other ◽  
Finite Element Analyses ◽  
Division 1 ◽  
Section Viii ◽  
Allowable Compressive Stress ◽  
Division 2

Abstract In the ASME Boiler and Pressure Vessel Code, nozzle reinforcement rules for nozzles attached to shells under external pressure differ from the rules for internal pressure. ASME BPVC Section I, Section VIII Division 1 and Section VIII Division 2 (Pre-2007 Edition) reinforcement rules for external pressure are less stringent than those for internal pressure. The reinforcement rules for external pressure published since the 2007 Edition of ASME BPVC Section VIII Division 2 are more stringent than those for internal pressure. The previous rule only required reinforcement for external pressure to be one-half of the reinforcement required for internal pressure. In the current BPVC Code the required reinforcement is inversely proportional to the allowable compressive stress for the shell under external pressure. Therefore as the allowable drops, the required reinforcement increases. Understandably, the rules for external pressure differ in these two Divisions, but the amount of required reinforcement can be significantly larger. This paper will examine the possible conservatism in the current Division 2 rules as compared to the other Divisions of the BPVC Code and the EN 13445-3. The paper will review the background of each method and provide finite element analyses of several selected nozzles and geometries.

The Effect of Joint Flexibility on the Torsion of a Vehicle Body

1982 ◽  
Vol 196 (1) ◽  
pp. 191-197 ◽  
Author(s):  
P W Sharman
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Theoretical Estimate ◽  
Element Model ◽  
Vehicle Body ◽  
Finite Element Analyses ◽  
Joint Flexibility ◽  
Theoretical Predictions ◽  
Plane Frame ◽  
Beam Type

Experiments on thin fabricated box members in a tee joint configuration revealed deformations which could not be correlated with beam-type models, even when spring elements were introduced at the joint. The behaviour was also observed in finite element analyses of the joints. Part of the cab structure of a heavy goods vehicle which formed a plane frame with fabricated members of closed cross-section was tested in torsion and the stiffness compared with theoretical predictions. The application of classical beam and torsional theory gave a result which was approximately ten times the experimental value. A further theoretical estimate, which included the joint flexibility as predicted by a finite element model of the localized region at the joint, gave an improved result which was 26 per cent higher than the experimental value.

Crushing and Wet Collapse of Flowline Carcasses: A Theoretical-Experimental Approach

2010 ◽  
Author(s):  
Celso P. Pesce ◽  
Clo´vis A. Martins ◽  
Alfredo Gay Neto ◽  
Andre´ L. C. Fujarra ◽  
Fernanda C. M. Takafuji ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Yield Stress ◽  
Experimental Approach ◽  
Theoretical Models ◽  
Element Model ◽  
Experimental Results ◽  
Sensitivity Analyses ◽  
Theoretical Predictions ◽  
Equivalent Ring

The present paper brings together theoretical predictions and experimental results, comparing crushing tests results as well as carcass wet collapse tests. The theoretical models are of two kinds: (i) numerical (FE) and (ii) analytical. The first kind is a restricted 3D version of a finite element model. The second kind is based on classic assumptions of equivalent ring behavior. Discussion is made on the real yield stress value to be adopted, as well as on the pertinence of geometric hypotheses. Sensitivity analyses, regarding ovalization and helical pitch are also presented.

Failure Strength Assessment of Pipes With Local Wall Thinning Under Combined Loading Based on Finite Element Analyses

2004 ◽  
Vol 126 (2) ◽  
pp. 179-183 ◽  
Author(s):  
Do-Jun Shim ◽  
Jae-Boong Choi ◽  
Young-Jin Kim
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Nuclear Power ◽  
Bending Moment ◽  
Combined Loading ◽  
Assessment Procedure ◽  
Finite Element Analyses ◽  
Maximum Moment ◽  
Wall Thinning ◽  
Local Wall Thinning

Failure assessment of a pipe with local wall thinning draws increasing attention in the nuclear power plant industry. Although many guidelines have been developed and are used for assessing the integrity of a wall-thinned pipeline, most of these guidelines consider only pressure loading and thus neglect bending loading. As most pipelines in nuclear power plants are subjected to internal pressure and bending moment, an assessment procedure for locally wall-thinned pipeline subjected to combined loading is urgently needed. In this paper, three-dimensional finite element (FE) analyses are carried out to simulate full-scale pipe tests conducted for various shapes of wall-thinned area under internal pressure and bending moment. Maximum moments based on ultimate tensile stress were obtained from FE results to predict the failure of the pipe. These results are compared with test results, showing good agreement. Additional finite element analyses are then performed to investigate the effect of key parameters, such as wall-thinned depth, wall-thinned angle and wall-thinned length, on maximum moment. Moreover, the effect of internal pressure on maximum moment was investigated. Change of internal pressure did not show significant effect on the maximum moment.

A Study on the Response of a Flexible Pipe to Combined Axisymmetric Loads

2013 ◽  
Author(s):  
José Renato M. de Sousa ◽  
Carlos Magluta ◽  
Ney Roitman ◽  
Tatiana V. Londoño ◽  
George C. Campello
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Internal Pressure ◽  
Reaction Force ◽  
Experimental Tests ◽  
Element Model ◽  
Tension Test ◽  
Experimental Results ◽  
Flexible Pipe ◽  
Pure Tension

In this work, the response of a 2.5″ flexible pipe to combined and pure axisymmetric loads is studied. A set of experimental tests was carried out and the results obtained are compared to those provided by a previously presented finite element model. The pipe was firstly subjected to pure tension. After that, the response to torsion superimposed with tension combined or not with internal pressure and the response to internal pressure combined with tension were investigated. In all these cases, the induced strains in the tensile armors were measured. Moreover, the axial elongation of the pipe was monitored in the pure tension test, whilst the twist of the pipe was measured when torsion was imposed and the axial reaction force was monitored when internal pressure was applied. The experimental results obtained agreed very well with the theoretical estimations indicating that the response of the pipe to tension and internal pressure is linear, whilst its response to torsion is nonlinear due to friction between layers.

Further Studies of Multiple Co-Planar Surface Breaking Flaws for Cleavage Fracture

2008 ◽  
Author(s):  
J. K. Sharples ◽  
M. A. Wilkes ◽  
D. W. Beardsmore ◽  
G. T. Melvin ◽  
M. Jackson
Keyword(s):  
Finite Element ◽  
Aspect Ratio ◽  
Cleavage Fracture ◽  
Failure Probability ◽  
Experimental Results ◽  
Finite Element Analyses ◽  
Aspect Ratios ◽  
The Uk ◽  
Single Flaw ◽  
Cleavage Failure

In assessing the integrity of structures, complex multiple flaws located in close proximity to each other are generally characterised as one, larger, single flaw. Guidance for the characterisation of multiple flaws is provided in procedures such as R6 and BS 7910, which are routinely used in the UK and elsewhere in the structural integrity assessment of structures and components. For this approach to be valid, the characterisation process must be conservative. That is to say, the probability of failure must be higher for the characterised flaw than for the system of multiple flaws. However, previous studies showed that the current characterisation rules may be non-conservative under some circumstances, in particular under cleavage fracture conditions. A combined experimental and analytical programme of work has been undertaken within the UK in order to further investigate this potential non-conservatism for situations where the possibility of cleavage failure may have to be taken into account when assessing structures or components containing multiple flaws. Details of early stages of the analytical programme were reported at the 2006 and 2007 ASME PVP Conferences and comprised a number of finite element analyses to evaluate cleavage failure probability, via a Master Curve-based approach, for interacting twin flaws and the corresponding characterised single flaw, under applied tensile and bending loads, at low temperatures. These analyses considered surface-breaking semi-elliptical flaws all having the same depth, but with four different aspect ratios. For each aspect ratio the separation of the twin flaws was varied. It was found that non-conservatism of the characterisation rules was indicated for flaws of high depth to length aspect ratio (a/c) in contact. This paper describes further work that has been undertaken to extend the results previously reported. The further work described has been centred on: • for the most onerous aspect ratio (a/c = 1.0) extending the experimental results to higher temperatures in the cleavage transition regime. • performing finite element analyses to complement these experiments. • revisiting the methods for calculation of cleavage failure probability to obtain improved agreement with the experimental results. • examining the rules governing the characterisation process, to determine if modification is necessary.

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