Effect of Bend Angle on Plastic Limit Loads of Pipe Bends Under In-Plane Bending Moment

Proceedings of the Institution of Mechanical Engineers, Part E:

2022

This study uses a three-dimensional nonlinear finite-element method to investigate the effects of bend angle ([Formula: see text]) and shape imperfection on the collapse load of pipe bends subjected to in-plane opening bending moment using large displacement analysis. ABAQUS was used to create a pipe bend model, whereas by virtue of symmetry about the longitudinal axis, half of the pipe bend model was built. The bend angle was varied from 30° to 180° with an interval of 30°, and shape imperfections, namely ovality ( Co) and thinning ( Ct), were varied from 0% to 20% each at 5% intervals. Elastic-perfectly plastic is thought to be the material of choice for the pipe bend. The results show that the bend angle has a significant impact on the collapse load of pipe bends between 30° and 120°, after which a significant decline was observed. The ovality impact increases with an increase in bend angle for pipe bends with a large thickness, whereas the opposite effect was found for smaller thicknesses with a small bend radius. The effect of bend radius and thickness was significant for large bend angles. Thinning ( Ct) and thickening ( Cth) have no effect on collapse load. A new mathematical equation has been proposed to predict the integrated effect of bend angle and shape imperfection.

Section: Deformation Behaviour Of Pipe Bendsmentioning

confidence: 99%

“…Kim et al 23 and Min et al 24 investigated small bend angles (0°-90°) pipe bend exposed to IP and IPCM. Li et al 25 investigated the effects on plastic limit loads in various pipe bend angles (30°-180°) subjected to IPCM/IPOM. However, they did not propose an analytical solution to the issue of limit load.…”

Section: Introductionmentioning

confidence: 99%

Determination of bend angle and shape imperfection effect on collapse load of pipe bends under in-plane opening moment

Silambarasan

Proceedings of the Institution of Mechanical Engineers, Part E:

2022

“…Gresnigt and van Foeken (1995) carried out extensive studies on 30°, 60°, 90° pressurized smooth bends exposed to IPCM, IPOM and out-of-plane bending loadings. S. Li, (2016) studied the consequence of bend angle (30°–180°) on the plastic limit loads of pipe subjected to IPCM/IPOM. Further, Li et al (2017) determined the limit loads of pipe bends with different bend angles subjected to IP, in-plane and out-of-plane bending moments and torsion moment.…”

Section: Literature Reviewmentioning

confidence: 99%

Combined effect of shape distortion and bend angle on collapse load of pipe bends under in-plane closing bending moment and internal pressure

Silambarasan

2021

WJE

Purpose The purpose of this paper is to quantify the combined effect of shape distortion and bend angle on the collapse loads of pipe bends exposed to internal pressure and in-plane closing bending moment. Non-linear finite element analysis with large displacement theory was performed considering the pipe bend material to be elastic perfectly plastic. Design/methodology/approach One half of the pipe bend model was built in ABAQUS. Shape distortion, namely, ovality (Co) and thinning (Ct), were each varied from 0% to 20% in steps of 5% and bend angle was varied from 30° to 180° in steps of 30°. Findings The findings show that ovality has a significant impact on collapse load. The effect of ovality decreases with an increase in bend angle for small thickness. The opposite effect was observed for large thickness pipe bends. The influence of ovality was more for higher bend angles. Ovality impact was almost negligible at certain internal pressure denoted as nullifying point (NP). The latter increased with an increase in pipe bend thickness and decreased with increase in pipe bend radius. For small bend angles one NP was observed where ovality impact is negligible and beyond this point the ovality effect increased. Two NPs were observed for large bend angles and ovality effect was maximum between the two NPs. Thinning yielded a minimal effect on collapse load except for small bend angles and bend radii. The influence of internal pressure on thinning was also negligible. Originality/value Influence of shape distortions and bend angle on collapse load of pipe bend exposed to internal pressure and in-plane closing bending has been not revealed in existing literature.

“…When C o exists in the pipe bend, it is imperative to estimate the collapse load and remarkable difference was seen between the collapse load of a pipe bend under IPCM and IPOM (Kale and Thorat, 2009;Kim and Oh, 2006). The bend radius also has a substantial influence on the plastic limit load behaviour of the pipe bend (Li, 2016). The twice elastic slope (TES) method was applied for the estimation of plastic collapse load of the pipe bend under IPCM and IP (Kim et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Investigation on structural integrity of shape distorted 90° back-to-back pipe bends under in-plane closing bending moment

Vinothkumar

2022

MMMS

PurposeThe aim of this study is to ensure the structural integrity of 90° back-to-back (B2B) pipe bends by developing a closed-form numerical solution for estimating the collapse load of shape distorted 90° B2B pipe bends using non-linear finite element (FE) analysis.Design/methodology/approachThe collapse behaviour of 90° B2B pipe bends with ovality (Co) and thinning (Ct) has been evaluated by non-linear FE approach. Moment load is applied in the form of in-plane closing moment (IPCM). The current FE approach was evaluated by the numerical solution for the plastic collapse moment of pipe bends, which has been published in the literature. The collapse moments were obtained from the twice elastic slope (TES) method using the moment-rotation curve of every individual model.FindingsThe implication of Ct/Cth on collapse load is found to be highly insignificant in terms of increasing bend radius and Co. Co weakens the geometry, and its effect on the collapse load is substantial. A closed-form numerical solution has been proposed to calculate the collapse load of 90° B2B pipe bend with shape imperfections.Originality/valueThe implications of shape distortion (Co and Ct) in the failure analysis (collapse load) of 90° B2B pipe bends has not been investigated and reported.