Evaluation of cyclic plasticity models in ratcheting simulation of straight pipes under cyclic bending and steady internal pressure

Pipelines and rigid risers are susceptible to corrosion. This is also a concern for pipes onshore and on process plants of floating platforms. Once detected the corrosion defect on pipes under cyclic loads, the analysis carried out to decide on keeping the pipe in operation or repair/replace should consider that the defect may experience cyclic plasticity caused by stress concentrations and thickness reductions. In this condition, ratcheting can cause rapid failure. This paper presents a study combining experiments and different analysis techniques to evaluate the occurrence of ratcheting in pipes subjected to cyclic bending and internal pressure. Experiments with different defect geometries were carried out. Numerical analysis using incremental plasticity and shakedown procedures are presented and compared with the experiments.

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Ratcheting assessment of corroded elbow pipes subjected to internal pressure and cyclic bending moment

The Journal of Strain Analysis for Engineering Design ◽

10.1177/0309324721989897 ◽

2021 ◽

pp. 030932472198989

Author(s):

Ali Salehi ◽

Armin Rahmatfam ◽

Mohammad Zehsaz

Keyword(s):

Growth Rate ◽

Stainless Steel ◽

Internal Pressure ◽

Bending Moment ◽

Axial Direction ◽

Hoop Strain ◽

Cyclic Bending ◽

High Fatigue ◽

The Impact ◽

Cyclic Bending Moment

The present study aimed to study ratcheting strains of corroded stainless steel 304LN elbow pipes subjected to internal pressure and cyclic bending moment. To this aim, spherical and cubical shapes corrosion are applied at two depths of 1 mm and 2 mm in the critical points of elbow pipe such as symmetry sites at intrados, extrados, and crown positions. Then, a Duplex 2205 stainless steel elbow pipe is considered as an alternative to studying the impact of the pipe materials, due to its high corrosion resistance and strength, toughness, and most importantly, the high fatigue strength and other mechanical properties than stainless steel 304LN. In order to perform numerical analyzes, the hardening coefficients of the materials were calculated. The results highlight a significant relationship between the destructive effects of corrosion and the depth and shape of corrosion, so that as corrosion increases, the resulting destructive effects increases as well, also, the ratcheting strains in cubic corrosions have a higher growth rate than spherical corrosions. In addition, the growth rate of the ratcheting strains in the hoop direction is much higher across the studied sample than the axial direction. The highest growth rate of hoop strain was observed at crown and the highest growth rate of axial strains occurred at intrados position. Altogether, Duplex 2205 material has a better performance than SS 304LN.

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Shakedown Limit Load Determination for a Kinematically Hardening 90-Degree Pipe Bend Subjected to Constant Internal Pressure and Cyclic Bending

Volume 3: Design and Analysis ◽

10.1115/pvp2007-26170 ◽

2007 ◽

Cited By ~ 2

Author(s):

Hany F. Abdalla ◽

Mohammad M. Megahed ◽

Maher Y. A. Younan

Keyword(s):

Finite Element ◽

Internal Pressure ◽

Plastic Material ◽

Kinematic Hardening ◽

Limit Load ◽

Material Behavior ◽

Pipe Bend ◽

Cyclic Bending ◽

Perfectly Plastic ◽

Shakedown Limit

A simplified technique for determining the shakedown limit load of a structure employing an elastic-perfectly-plastic material behavior was previously developed and successfully applied to a long radius 90-degree pipe bend. The pipe bend is subjected to constant internal pressure and cyclic bending. The cyclic bending includes three different loading patterns namely; in-plane closing, in-plane opening, and out-of-plane bending moment loadings. The simplified technique utilizes the finite element method and employs small displacement formulation to determine the shakedown limit load without performing lengthy time consuming full cyclic loading finite element simulations or conventional iterative elastic techniques. In the present paper, the simplified technique is further modified to handle structures employing elastic-plastic material behavior following the kinematic hardening rule. The shakedown limit load is determined through the calculation of residual stresses developed within the pipe bend structure accounting for the back stresses, determined from the kinematic hardening shift tensor, responsible for the translation of the yield surface. The outcomes of the simplified technique showed very good correlation with the results of full elastic-plastic cyclic loading finite element simulations. The shakedown limit moments output by the simplified technique are used to generate shakedown diagrams of the pipe bend for a spectrum of constant internal pressure magnitudes. The generated shakedown diagrams are compared with the ones previously generated employing an elastic-perfectly-plastic material behavior. These indicated conservative shakedown limit moments compared to the ones employing the kinematic hardening rule.

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Ratcheting of corroded pipes under cyclic bending and internal pressure

International Journal of Pressure Vessels and Piping ◽

10.1016/j.ijpvp.2014.09.002 ◽

2015 ◽

Vol 125 ◽

pp. 35-48 ◽

Cited By ~ 6

Author(s):

Marcelo Igor Lourenço ◽

Theodoro Antoun Netto

Keyword(s):

Internal Pressure ◽

Cyclic Bending

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Mechanism Study on the Coiled Tubing Deformation under a Combination Loading

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.328-330.1528 ◽

2011 ◽

Vol 328-330 ◽

pp. 1528-1532 ◽

Cited By ~ 3

Author(s):

Lei Li ◽

Zhao Xi Shen ◽

Peng Wang

Keyword(s):

Internal Pressure ◽

Deformation Behavior ◽

Fatigue Tests ◽

Deformation Mechanisms ◽

Pressure Loading ◽

Mechanism Study ◽

Cyclic Bending ◽

Coiled Tubing ◽

Combination Loading

The tendency for coiled tubing to grow in diameter and thin in wall under a combination loading of internal pressure and cyclic bending. This can occur in spite of the fact that nominal stresses due to internal pressure loading are well within elastic limits in both hoop and radial directions. The deformation mechanisms are described. Fatigue tests of 10 coiled tubing specimens are finished. The results show that the trends in coiled tubing deformation behavior are according with the context of theory.

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CONTINUUM DAMAGE MECHANICS ANALYSIS OF THIN-WALLED TUBE UNDER CYCLIC BENDING AND INTERNAL CONSTANT PRESSURE

International Journal of Applied Mechanics ◽

10.1142/s1758825113500385 ◽

2013 ◽

Vol 05 (04) ◽

pp. 1350038 ◽

Cited By ~ 14

Author(s):

H. YAZDANI ◽

A. NAYEBI

Keyword(s):

Internal Pressure ◽

Damage Mechanics ◽

Low Cycle Fatigue ◽

Kinematic Hardening ◽

Damage Model ◽

Continuum Damage Mechanics ◽

Continuum Damage ◽

Cyclic Bending ◽

Thin Walled Tube ◽

Thin Walled

Ratcheting and fatigue damage of thin-walled tube under cyclic bending and steady internal pressure is studied. Chaboche's nonlinear kinematic hardening model extended by considering the effect of continuum damage mechanics employed to predict ratcheting. Lemaitre damage model [Lemaitre, J. and Desmorat, R. [2005] Engineering Damage Mechanics (Springer-Verlag, Berlin)] which is appropriate for low cyclic loading is used. Also the evolution features of whole-life ratcheting behavior and low cycle fatigue (LCF) damage of the tube are discussed. A simplified method related to the thin-walled tube under bending and internal pressure is used and compared well with experimental results. Bree's interaction diagram with boundaries between shakedown and ratcheting zone is determined. Whole-life ratcheting of thin-walled tube reduces obviously with increase of internal pressure.

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Shakedown Limit Loads for 90 Degree Scheduled Pipe Bends Subjected to Steady Internal Pressure and Cyclic Bending Moments

Journal of Pressure Vessel Technology ◽

10.1115/1.4002055 ◽

2011 ◽

Vol 133 (3) ◽

Cited By ~ 6

Author(s):

Hany F. Abdalla ◽

Mohammad M. Megahed ◽

Maher Y. A. Younan

Keyword(s):

Finite Element ◽

Internal Pressure ◽

Pressure Vessel ◽

Limit Load ◽

Small Displacement ◽

Bending Moments ◽

Pipe Bend ◽

Hardening Material ◽

Cyclic Bending ◽

Shakedown Limit

A simplified technique for determining the shakedown limit load for a long radius 90 deg pipe bend was previously developed (Abdalla, H. F., et al., 2006, “Determination of Shakedown Limit Load for a 90 Degree Pipe Bend Using a Simplified Technique,” ASME J. Pressure Vessel Technol., 128, pp. 618–624; Abdalla, H. F., et al., 2007, “Shakedown Limits of a 90-Degree Pipe Bend Using Small and Large Displacement Formulations,” ASME J. Pressure Vessel Technol., 129, pp. 287–295). The simplified technique utilizes the finite element (FE) method and employs the small displacement formulation to determine the shakedown limit load (moment) without performing lengthy time consuming full cyclic loading finite element simulations or utilizing conventional iterative elastic techniques. The shakedown limit load is determined through the calculation of residual stresses developed within the pipe bend structure. In the current paper, a parametric study is conducted through applying the simplified technique on three scheduled pipe bends, namely, nominal pipe size (NPS) 10 in. Sch. 20, NPS 10 in. Sch. 40 STD, and NPS 10 in. Sch. 80. Two material models are assigned, namely, an elastic perfectly plastic (EPP) material and an idealized elastic-linear strain hardening material obeying Ziegler’s linear kinematic hardening (KH) rule. This type of material model is termed in the current study as the KH-material. The pipe bends are subjected to a spectrum of steady internal pressure magnitudes and cyclic bending moments. The cyclic bending includes three different loading patterns, namely, in-plane closing, in-plane opening, and out-of-plane bending moment loadings of the pipe bends. The shakedown limit moments outputted by the simplified technique are used to generate shakedown diagrams of the scheduled pipe bends for the spectrum of steady internal pressure magnitudes. A comparison between the generated shakedown diagrams for the pipe bends employing the EPP- and the KH-materials is presented. Relatively higher shakedown limit moments were recorded for the pipe bends employing the KH-material at the medium to high internal pressure magnitudes.

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Shakedown Limit Load Determination for a Kinematically Hardening 90 deg Pipe Bend Subjected to Steady Internal Pressures and Cyclic Bending Moments

Journal of Pressure Vessel Technology ◽

10.1115/1.4003474 ◽

2011 ◽

Vol 133 (5) ◽

Cited By ~ 4

Author(s):

Hany F. Abdalla ◽

Maher Y. A. Younan ◽

Mohammad M. Megahed

Keyword(s):

Cyclic Loading ◽

Internal Pressure ◽

Limit Load ◽

Material Model ◽

Small Displacement ◽

Bending Moments ◽

Pipe Bend ◽

Cyclic Bending ◽

Fe Simulations ◽

Shakedown Limit

A simplified technique for determining the lower bound shakedown limit load of a structure, employing an elastic–perfectly plastic (EPP) material model, was previously developed and successfully applied to a long radius 90 deg pipe bend (Abdalla et al., 2006, “Determination of Shakedown Limit Load for a 90 Degree Pipe Bend Using a Simplified Technique,” ASME J. Pressure Vessel Technol., 128, pp. 618–624). The pipe bend is subjected to steady internal pressure magnitudes and cyclic bending moments. The cyclic bending includes three different loading patterns, namely, in-plane closing, in-plane opening, and out-of-plane bending moment loadings. The simplified technique utilizes the finite element (FE) method and employs a small displacement formulation to determine the shakedown limit load without performing lengthy time consuming full elastic-plastic (ELPL) cyclic loading FE simulations or conventional iterative elastic techniques. In the present research, the simplified technique is further modified to handle structures employing an elastic-linear strain hardening material model following Ziegler’s linear kinematic hardening (KH) rule. The shakedown limit load is determined through the calculation of residual stresses developed within the pipe bend structure accounting for the back stresses, determined from the KH shift tensor, responsible for the rigid translation of the yield surface. The outcomes of the simplified technique showed an excellent correlation with the results of full ELPL cyclic loading FE simulations. The shakedown limit moments output by the simplified technique are utilized to generate shakedown diagrams (Bree diagrams) of the pipe bend for a spectrum of steady internal pressure magnitudes. The generated Bree diagrams are compared with the ones previously generated employing the EPP material model. These indicated relatively conservative shakedown limit moments compared with the ones employing the KH rule.

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Ratcheting Studies on Type 304LN Stainless Steel Elbows subjected to Combined Internal Pressure and In-Plane Bending Moment

Journal of Pressure Vessel Technology ◽

10.1115/1.4005886 ◽

2012 ◽

Vol 134 (4) ◽

Cited By ~ 3

Author(s):

S. Vishnuvardhan ◽

G. Raghava ◽

P. Gandhi ◽

M. Saravanan ◽

D. M. Pukazhendhi ◽

...

Keyword(s):

Stainless Steel ◽

Internal Pressure ◽

Accumulation Rate ◽

Bending Moment ◽

Cyclic Bending ◽

Ratcheting Strain ◽

Bending Load ◽

304Ln Stainless Steel ◽

Number Of Cycles ◽

Opening And Closing

“Ratcheting” is a phenomenon which leads to reduction in fatigue life of a structural component by loss of ductility due to cycle by cycle accumulation of plastic strain. Ratcheting occurs in a structure subjected to a combination of steady/sustained and cyclic loads such that the material response is in inelastic region. Ratcheting studies were carried out on Type 304LN stainless steel elbows, subjected to steady internal pressure and cyclic bending. The elbows filled with water were pressurized between 27.6 MPa and 39.2 MPa. Cyclic bending load, under opening and closing moments, was applied on the elbows at ambient temperature. Number of cycles corresponding to occurrence of a through-wall crack was recorded. Crack was observed in the bent portion at one of the crown locations in all the four specimens. Maximum strain was observed at the intrados and crown locations of the elbows. The ratcheting strain increased with number of cycles at crown and intrados locations. However, the strain accumulation rate decreased with number of cycles. Strain was observed to be minimum at the extrados location and the same stabilized toward the end of the tests. The specimens have failed by occurrence of through-wall axial crack accompanied by simultaneous ballooning. The ballooning was found to be varying from 3.8% to 5.8% with respect to the original circumference in the bent portion. The reduction in thickness was found to be around 12%–15%.

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