Effect of bend angle on plastic loads of pipe bends under internal pressure and in-plane bending

Kim, Yun Jae; Lee, Kuk Hee; Oh, Chang Sik; Yoo, Bong; Park, Chi Yong

doi:10.1016/j.ijmecsci.2007.03.006

Cited by 42 publications

(18 citation statements)

References 10 publications

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“…Figure 8 summarizes FE results for the effect of non‐uniform thicknesses on plastic loads for elbows under in‐plane opening bending for four different choices of the representative thickness: (i) t rep = t e , (ii) t rep = t c , (iii) t rep = t s and (iv) t rep = t wa , given by . The FE plastic moments M FE o are normalized with respect to estimated ones M est o . Estimations are made using the closed‐form solution proposed by the author, 20 given by …”

Section: Results and Discussion For In‐plane Bendingmentioning

confidence: 99%

“…For all cases, three elements are used through the thickness. In our previous work, 20 sensitivity analysis was performed with finer meshes having almost twice the number of elements (six elements through the thickness). It was shown that the results were almost identical, suggesting that the presented FE meshes are sufficiently fine for the present purpose.…”

Section: Finite‐element Limit Analysesmentioning

confidence: 99%

“…Determination of plastic loads for elbows is important in structural integrity analysis of piping components. Numerous papers can be found in literature, including analytical works, 1–3 experimental works 4–7 and numerical works 7–20 . Closed‐form solutions for plastic loads of elbows have been proposed, for instance, under internal pressure, 3 in‐plane bending, 1–3,13,17–20 and combined pressure and bending 12,13,18 .…”

Section: Introductionmentioning

confidence: 99%

“…E-mail: kimy0308@korea.ac.kr merous papers can be found in literature, including analytical works, 1-3 experimental works [4][5][6][7] and numerical works. [7][8][9][10][11][12][13][14][15][16][17][18][19][20] Closed-form solutions for plastic loads of elbows have been proposed, for instance, under internal pressure, 3 in-plane bending, [1][2][3]13,[17][18][19][20] and combined pressure and bending. 12,13,18 One interesting point to note is that all existing works assume that elbows have a constant thickness.…”

Section: Introductionmentioning

confidence: 99%

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A method to estimate plastic loads for elbows with non‐uniform thicknesses

Kim

et al. 2008

Fatigue Fract Eng Mat Struct

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A B S T R A C T This paper provides a method to estimate plastic loads [defined by the twice-elasticslope (TES)] for elbows with non-uniform thicknesses under in-plane bending and under internal pressure, based on systematic FE limit analyses using elastic-perfectly plastic materials. The intrados thickness is assumed to be up to 30% thicker than the straight pipe thickness, whereas the extrados thickness up to 30% thinner. The FE plastic loads are compared with estimated ones using closed-form approximations for elbows with uniform thicknesses, to provide guidance on the choice of a representative thickness to predict plastic loads for elbows with non-uniform thicknesses. Results suggest that the use of the straight pipe thickness gives overall satisfactory predictions. Estimated plastic loads are conservative, and differ from FE results by less than 10% for all cases considered. Despite its simplicity, results look very promising, and thus the use of the straight pipe thickness can be recommended to estimate plastic loads for elbows with non-uniform thicknesses in practice.M o = limit in-plane moment of an elbow P o = limit pressure of an elbow P o s = limit pressure of a straight pipe r = mean pipe radius R = bend radius t = thickness (general); thickness of an elbow with an uniform-thickness t s = thickness of a straight pipe attached to an elbow t rep = representative thickness of an elbow with non-uniform thicknesses t i , t e , t c = thickness at intrados, extrados and crown in the elbow mid-section, respectively t i , t e , t c = thickness differences at intrados, extrados and crown in the elbow mid-section, respectively φ = bend angle (Fig. 1) λ = bend characteristic = Rt r 2 σ o = yield strength ψ, ξ = angles characterizing spatial position within an elbow (Fig. 1)

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Section: Results and Discussion For In‐plane Bendingmentioning

confidence: 99%

Section: Finite‐element Limit Analysesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A method to estimate plastic loads for elbows with non‐uniform thicknesses

Kim

et al. 2008

Fatigue Fract Eng Mat Struct

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“…At room temperature the researches on pipe with LWT focused on the stress analysis [3][4][5][6][7], limit load [8][9][10][11][12][13][14], fracture behavior [15][16][17][18][19][20], safety assessment [21] and fatigue behavior [22,23]. Different pipe types (straight pipe [9,10], elbow pipe [8,11,12] and tee pipe [20]), different load types (internal pressure [4,8], bending load [10,17] and combined loads [7,13,14]) and different defect numbers (single LWT [3][4][5]9,10] and multiple LWTs [21]) were considered by different research methods (finite element method [3,7,12] and experimental method [8,9,17]). Many meaningful results have been obtained.…”

Section: Introductionmentioning

confidence: 99%

Ultimate creep load and safety assessment of P91 steel pipe with local wall thinning at high temperature

Xue

Zhou

Peng

2015

International Journal of Mechanical Sciences

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Plastic loads of pipe bends under combined pressure and out-of-plane bending

Lee¹,

Kim²,

Park

2008

Int J Fract

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This paper provides plastic limit and TES (twice-elastic-slope) plastic load solutions for 90 • pipe bends under combined pressure and out-of-plane bending, via threedimensional non-linear FE analyses using elastic-perfectly plastic materials. Without internal pressure, a closed-form approximation is given. For combined pressure and out-of-plane bending, tabulated data are given, from which TES plastic loads can be interpolated. It is found that TES plastic loads for pipe bends under out-of-plane bending are lower than those under in-plane opening bending, but are higher than those under in-plane closing bending. It suggests that the in-plane closing bending mode is the most critical loading mode for 90 • pipe bends, which is fully consistent to existing findings.Keywords Combined pressure and out-of-plane bending · Finite element limit analysis · Pipe Bend · Twice-elastic-slope plastic load Nomenclature E Young's modulus M Out-of-plane bending moment M o TES plastic out-of-plane moments of pipe bends P Internal pressure P o Limit pressure of a pipe bend P s o Limit pressure of a straight pipe = 2 √ 3 σ o t r R Bend radius r Mean pipe radius t Thickness of pipe

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Effect of bend angle on plastic loads of pipe bends under internal pressure and in-plane bending

Cited by 42 publications

References 10 publications

A method to estimate plastic loads for elbows with non‐uniform thicknesses

A method to estimate plastic loads for elbows with non‐uniform thicknesses

Ultimate creep load and safety assessment of P91 steel pipe with local wall thinning at high temperature

Plastic loads of pipe bends under combined pressure and out-of-plane bending

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