Stress Concentration Factors for a Drilling Riser Containing Corrosion Pits

2007 ◽  
Author(s):  
Adilson C. Benjamin ◽  
Divino J. S. Cunha ◽  
Rita C. C. Silva ◽  
Joa˜o N. C. Guerreiro ◽  
George C. Campello ◽  
...  
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Wall Thickness ◽  
External Surface ◽  
Corrosion Defects ◽  
Concentration Factors ◽  
Residual Fatigue ◽  
Stress Concentration Factors ◽  
Corrosion Pits ◽  
Outside Diameter

The residual fatigue life of a corroded riser joint can be evaluated by means of a fatigue analysis based on S-N data. In this case nominal stresses are determined through a global riser analysis in which the drilling riser is modeled as a tensioned beam subjected to loads throughout its length and with boundary conditions at each end. The effect of the corrosion defects is taken into account multiplying the nominal stresses by stress concentration factors (SCFs) derived by local Finite Element (FE) analyses of the riser joints containing corrosion defects. In this paper stress concentration factors for a drilling riser containing corrosion pits are calculated using solid FE models. These pits are situated on the external surface of the riser joints. Three shapes of corrosion pits are considered: semi spherical, cylindrical wide and cylindrical narrow. Five depths of corrosion pits are considered: 12.6%, 20.1%, 30.2%, 40.3% and 50.3% of the riser wall thickness. The riser outside diameter and the riser wall thickness are 533.4 mm (21 in) and 15.9 mm (0.625 in), respectively.

The Stress Concentration Factor of Different Corrosion Pits Shape

2010 ◽  
Vol 152-153 ◽  
pp. 1115-1119 ◽  
Author(s):  
Zhi Tao Mu ◽  
Ding Hai Chen ◽  
Zuo Tao Zhu ◽  
Bin Ye
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Concentration Effect ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Corrosion Pits ◽  
Stress Concentration Effect

The stress concentration effect of different corrosion pits is different, the shapes of corrosion pits can be seen as semi-ellipsoidal, the short half axes、long half axes and depth of corrosion are 、 and , through finite element analyze, we can see that the stress concentration factors increase with the increase of , but the stress concentration factors decrease with the increase of .

Stress concentration factors for the torsion of curved beams of arbitrary cross-section

2006 ◽  
Vol 220 (12) ◽  
pp. 1709-1726 ◽  
Author(s):  
R E Cornwell
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Cross Section ◽  
Cross Sections ◽  
Shear Stresses ◽  
Curved Beams ◽  
Finite Element Implementation ◽  
Out Of Plane ◽  
Concentration Factors ◽  
Stress Concentration Factors

There are numerous situations in machine component design in which curved beams with cross-sections of arbitrary geometry are loaded in the plane of curvature, i.e. in flexure. However, there is little guidance in the technical literature concerning how the shear stresses resulting from out-of-plane loading of these same components are effected by the component's curvature. The current literature on out-of-plane loading of curved members relates almost exclusively to the circular and rectangular cross-sections used in springs. This article extends the range of applicability of stress concentration factors for curved beams with circular and rectangular cross-sections and greatly expands the types of cross-sections for which stress concentration factors are available. Wahl's stress concentration factor for circular cross-sections, usually assumed only valid for spring indices above 3.0, is shown to be applicable for spring indices as low as 1.2. The theory applicable to the torsion of curved beams and its finite-element implementation are outlined. Results developed using the finite-element implementation agree with previously available data for circular and rectangular cross-sections while providing stress concentration factors for a wider variety of cross-section geometries and spring indices.

Analysis of Stress Concentrations in Thick Cylinders With Sideholes and Crossholes

1972 ◽  
Vol 94 (3) ◽  
pp. 815-824 ◽  
Author(s):  
J. C. Gerdeen
Keyword(s):  
Stress Concentration ◽  
Stress Concentrations ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Experimental Values ◽  
Pressure Stress ◽  
Shrink Fit ◽  
Outside Diameter ◽  
Theoretical Results

An approximate theoretical analysis is presented for the determination of stress concentration factors in thick walled cylinders with sideholes and crossholes. The cylinders are subjected to both internal pressure and external shrink-fit pressure. Stress concentration factors are plotted as functions of the geometrical ratios of outside diameter-to-bore diameter, and bore diameter-to-sidehole diameter. Theoretical results are compared to experimental values available in the literature and results of experiments described in a separate paper.

An Estimation Formula of the Stress Concentration Factor of the Butt-Welded Joint

2007 ◽  
Vol 353-358 ◽  
pp. 1995-1998
Author(s):  
Byeong Choon Goo
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Gas Metal Arc Welding ◽  
Element Analysis ◽  
Butt Weld ◽  
Estimation Formula ◽  
Metal Arc Welding ◽  
Concentration Factors ◽  
Stress Concentration Factors

The purpose of this paper is to develop an estimation formula of stress concentration factors of butt-welded components under tensile loading. To investigate the influence of weld bead profiles on stress concentration factors of double V groove butt-welded joints, butt-welded specimens were made by CO2 gas metal arc welding. And the three main parameters, the toe radius, flank angle and bead height were measured by a profile measuring equipment. By using the measured data, the influence of three parameters on the stress concentration factors was investigated by a finite element analysis. It is shown that the three parameters have similar effects on the stress concentration factors. According to the simulation results, a formula to estimate the stress concentration factors of butt-weld welded structures was proposed and the estimated concentration factors from the formula were compared with the results obtained by the finite element analysis. The two results are in a good agreement.

Experimental, numerical and parametric studies on stress concentration factors of T-joints under tension

2021 ◽  
pp. 136943322110499
Author(s):  
Feleb Matti ◽  
Fidelis Mashiri
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Numerical Study ◽  
Hot Spot ◽  
Joint Models ◽  
Element Analysis ◽  
T Joints ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Good Agreement

This paper investigates the behaviour of square hollow section (SHS) T-joints under static axial tension for the determination of stress concentration factors (SCFs) at the hot spot locations. Five empty and corresponding concrete-filled SHS-SHS T-joint connections were tested experimentally and numerically. The experimental investigation was carried out by attaching strain gauges onto the SHS-SHS T-joint specimens. The numerical study was then conducted by developing three-dimensional finite element (FE) T-joint models using ABAQUS finite element analysis software for capturing the distribution of the SCFs at the hot spot locations. The results showed that there is a good agreement between the experimental and numerical SCFs. A series of formulae for the prediction of SCF in concrete-filled SHS T-joints under tension were proposed, and good agreement was achieved between the maximum SCFs in SHS T-joints calculated from FE T-joint models and those from the predicted formulae.

An Assessment of Structural Details in Lightweight Marine Structures

2004 ◽  
Author(s):  
Carlos A. Pereira ◽  
Paulo P. Silva ◽  
Anto´nio F. Mateus ◽  
Joel A. Witz
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Failure Modes ◽  
Marine Structures ◽  
Element Analysis ◽  
Linear Finite Element ◽  
Structural Details ◽  
Concentration Factors ◽  
Stress Concentration Factors

This paper presents the results of investigations into the mechanics and failure modes of structural details usually encountered in lightweight marine structures. The structural analyses are performed using non-linear finite element analysis. The stress concentration factors and expected fatigue lives of the as designed and the as built structural details are evaluated and alternative configurations are discussed with the aim of improving the designs for production.

scholarly journals DETERMINATION OF STRESS CONCENTRATION FACTORS OF A STEAM TURBINE ROTOR USING FINITE ELEMENT ANALYSIS

1970 ◽  
Vol 40 (2) ◽  
pp. 137-141
Author(s):  
R. Nagendra Babu ◽  
K. V. Ramana ◽  
K. Mallikarjuna Rao
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Steam Turbine ◽  
Turbine Rotor ◽  
Element Analysis ◽  
Steam Turbine Rotor ◽  
Fine Mesh ◽  
Concentration Factors ◽  
Stress Concentration Factors

Stress Concentration Factors are significant in machine design as it gives rise to localized stress when any change in the design of surface or abrupt change in the cross section occurs. Almost all machine components and structural members contain some form of geometrical or microstructural discontinuities. These discontinuities are very dangerous and lead to failure. So, it is very much essential to analyze the stress concentration factors for critical applications like Turbine Rotors. In this paper Finite Element Analysis (FEA) with extremely fine mesh in the vicinity of the blades of Steam Turbine Rotor is applied to determine stress concentration factors.Keywords: Stress Concentration Factors; FiniteElement Analysis; ANSYS.DOI: 10.3329/jme.v40i2.5355Journal of Mechanical Engineering, Vol. ME 40, No. 2, December 2009 137-141

Fatigue Assessment of Damaged Pipelines After Glass Fiber and Epoxy Matrix Laminate Repairs

2017 ◽  
Author(s):  
Sabrina Regalla ◽  
Bianca Pinheiro ◽  
Ilson Pasqualino ◽  
Luiz Daniel Lana ◽  
Valber Perrut
Keyword(s):  
Stress Concentration ◽  
Internal Pressure ◽  
Epoxy Matrix ◽  
Glass Fibers ◽  
Before And After ◽  
Repair Procedure ◽  
Concentration Factors ◽  
Residual Fatigue ◽  
Stress Concentration Factors ◽  
Fatigue Life Enhancement

The aim of this work is to evaluate the residual fatigue life enhancement of damaged pipelines after the execution of composite material repairs made of laminates of epoxy matrix reinforced with glass fibers. In view of structural performance and cost concerns, the more suitable repair thickness should be proposed. The work comprises a numerical and experimental study on the stress concentration of damaged pipes under internal pressure before and after repair. A numerical model is developed, based on the finite element method, to provide stress concentration factors of damaged pipes (plain dent defect), under cyclic internal pressure, before and after applying glass fiber and epoxy matrix laminate repairs with varying thicknesses. Small-scale steel pipe samples are submitted to denting and the resulting stress concentration in the damaged region is estimated under cyclic internal pressure, before and after repair execution. From correlation between numerical and experimental results, the finite element model is calibrated and validated. A parametric study is carried out to evaluate stress concentration factors of dented pipes repaired with varying laminate thickness. Stress concentration factors of dented pipes under internal pressure after repair can be used in a fatigue assessment methodology from correction of S-N curves. The effect of repair thickness on the reduction of stress concentration factors is evaluated in view of the residual fatigue life enhancement of damaged pipes, beside repair procedure costs. Based on results of the parametric study, recommendations about the repair procedure using laminates of epoxy matrix reinforced with glass fibers will be proposed, comprising indications of the more suitable repair thickness, as a function of pipe and damage dimensions, in view of fatigue performance and cost concerns.

Finite Element Analysis and Fatigue Evaluation of the Threaded Marine Riser Connector

1988 ◽  
Vol 110 (2) ◽  
pp. 85-92 ◽  
Author(s):  
T. Sato ◽  
S. Sano ◽  
K. Ishikawa ◽  
T. Nakano
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
External Pressure ◽  
Axisymmetric Body ◽  
Large Contribution ◽  
Marine Riser ◽  
Element Analysis ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Fatigue Evaluation

Finite element analyses were conducted of the threaded marine riser connector which has the main, internal, and external shoulder seals. The objectives of the analyses are to evaluate the fatigue resistance, strength, and seal capability of the connector under the bending, tensile, internal and external pressure loads. An element which models the bending effect in an axisymmetric body is developed and implemented into the computer program ADINA. Using the program, stress concentration factors at the corner and threaded parts of the connector under these loads are obtained. The large contribution of both shoulders to the reduction of the stress concentration factors is found to be quite clear. The seal mechanism and the stress response of the connectors are also clarified. The fatigue evaluation based on ASME Boiler and Pressure Vessel Code, Sec. III, Rules for Construction of Nuclear Power Plant Components, Division 1, Subsection NB are compared with the experimental results.

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