Failure of GRP Pipe Bends Under Out-of-Plane Flexure with and Without Pressure

1993 ◽  
Vol 207 (2) ◽  
pp. 133-141
Author(s):  
R Kitching ◽  
P Myler
Keyword(s):  
Internal Pressure ◽  
Polyester Resin ◽  
Design Procedure ◽  
Out Of Plane ◽  
Failure Loads ◽  
Smooth Pipe ◽  
Plane Bending ◽  
Chopped Strand Mat ◽  
Plane Flexure

Tests to failure have been carried out on six smooth pipe bends constructed by hand lay-up from polyester resin and glass in the form of chopped strand mat. The failure loads under out-of-plane bending only are compared with those where this type of loading is combined with internal pressure. The results are discussed in relation to the design procedure adopted in BS 7159: 1989.

GRP pipe bends subjected to out-of-plane flexure with and without pressure

1988 ◽  
Vol 23 (4) ◽  
pp. 187-199 ◽  
Author(s):  
R Kitching ◽  
P Myler ◽  
A L Tan
Keyword(s):  
Constant Pressure ◽  
Design Procedure ◽  
Bending Stress ◽  
Bend Radius ◽  
Pipe Bend ◽  
Bending Tests ◽  
Out Of Plane ◽  
Chopped Strand Mat ◽  
Plane Flexure ◽  
Typical Design

Out-of-plane bending tests were carried out on eight E-glass reinforced polytester resin, 90 degree pipe bends of 250 mm diameter and 250 mm bend radius. Each bend specimen tested had 1175 mm long tangent pipes attached, and construction was by hand lay-up, the glass being in the form of chopped strand mat (either 2.4 kg/m2 or 3.6 kg/m2). In all cases low loads were applied so that deformations were sensibly linear. Strains and displacements were measured and distributions were compared with estimates calculated from pipe bend theory for isotropic materials under plane stress, but modified for composites by using separate moduli for direct and bending stress conditions. Further measurements were taken for internal pressure (only) loadings on five of the specimens, and finally for out-of-plane flexure loading combined with constant pressure. Again measured values were compared with theory. Results are discussed in relation to a typical design procedure for such pipe components.

Stress and flexibility factors for multi-mitred pipe bends subjected to internal pressure combined with external loadings

1972 ◽  
Vol 7 (2) ◽  
pp. 97-108 ◽  
Author(s):  
M P Bond ◽  
R Kitching
Keyword(s):  
Internal Pressure ◽  
Large Diameter ◽  
Pipe Bend ◽  
Bending Tests ◽  
Bending Load ◽  
Out Of Plane ◽  
Thin Walled ◽  
Plane Bending ◽  
Internal Pressures ◽  
Stress Patterns

The stress analysis of a multi-mitred pipe bend when subjected to an internal pressure and a simultaneous in-plane or out-of-plane bending load has been developed. Stress patterns and flexibility factors calculated by this analysis are compared with experimental results from a large-diameter, thin-walled, three-weld, 90° multi-mitred bend which was subjected to in-plane bending tests at various internal pressures.

Plastic Collapse Assessment Procedure in P-M Diagram Method for Pipe Bends With a Local Thin Area Under Combined Pressure and Out-of-Plane Bending Moment

2012 ◽  
Author(s):  
Kenji Oyamada ◽  
Shinji Konosu ◽  
Takashi Ohno
Keyword(s):  
Internal Pressure ◽  
Pressure Ratio ◽  
Bending Moment ◽  
Piping System ◽  
Assessment Procedure ◽  
Plastic Collapse ◽  
Diagram Method ◽  
Out Of Plane ◽  
Plane Bending ◽  
Collapse Assessment

Pipe bends are common elements in piping system such as power or process piping, and local thinning are typically occurred on pipe bends due to erosion or corrosion. Therefore, it is important to establish the plastic collapse condition for pipe bends having a local thin area (LTA) under combined internal pressure and external bending moment. In this paper, a simplified plastic collapse assessment procedure in p-M (internal pressure ratio and external bending moment ratio) diagram method for pipe bends with a local thin area simultaneously subjected to internal pressure, p, and external out-of-plane bending moment, M, due to earthquake, etc., is proposed, which is derived from the reference stress. In this paper, only cases of that an LTA is located in the crown of pipe bends are considered. The plastic collapse loads derived from the p-M diagram method are compared with the results of both experiments and FEA for pipe bends of the same size with various configurations of an LTA.

Theory of thin elastic shells applied to pipe bends subjected to bending and internal pressure

1972 ◽  
Vol 7 (4) ◽  
pp. 285-293 ◽  
Author(s):  
J A Blomfield ◽  
C E Turner
Keyword(s):  
Internal Pressure ◽  
Shell Theory ◽  
Coupling Effect ◽  
Governing Equations ◽  
Elastic Shells ◽  
Out Of Plane ◽  
Plane Bending

A consistent set of equations for the in-plane and out-of-plane bending of pipe bends is derived from the equations of shell theory with a correction for the coupling effect of internal pressure. The resulting governing equations are solved numerically and compared with other experimental and theoretical solutions.

Evaluation of collapse moment of pressurized 30°–180° bend pipes subjected to out-of-plane bending moment

2021 ◽  
pp. 095440622110614
Author(s):  
Manish Kumar ◽  
Pronab Roy ◽  
Kallol Khan
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Plastic Material ◽  
Bending Moment ◽  
Bend Angle ◽  
Pipe Bend ◽  
Geometric Imperfection ◽  
Initial Geometric Imperfection ◽  
Out Of Plane ◽  
Plane Bending

The present paper determines collapse moments of pressurized 30°–180° pipe bends incorporated with initial geometric imperfection under out-of-plane bending moment. Extensive finite element analyses are carried out considering material as well as geometric nonlinearity. The twice-elastic-slope method is used to determine collapse moment. The results show that initial imperfection produces significant change in collapse moment for unpressurized pipe bends and pipe bends applied to higher internal pressure. The application of internal pressure produces stiffening effect to pipe bends which increases collapse moment up to a certain limit and with further increase in pressure, collapse moment decreases. The bend angle effect on collapse moment reduces with the increase in internal pressure and bend radius. Based on finite element results, collapse moment equations are formed as a function of the pipe bend geometry parameters, initial geometric imperfection, bend angle, and internal pressure for elastic-perfectly plastic material models.

Shakedown Boundary of a 90–Degree Back–to–Back Pipe Bend Subjected to Steady Internal Pressures and Cyclic Out–of–Plane Bending Moments

2014 ◽  
Author(s):  
Hany F. Abdalla
Keyword(s):  
Internal Pressure ◽  
Bending Moment ◽  
Bending Moments ◽  
Pipe Bend ◽  
Structure Comparison ◽  
Out Of Plane ◽  
Plane Bending ◽  
Shakedown Limit ◽  
Elastic Shakedown ◽  
Internal Pressures

Ninety degree back–to–back pipe bends are extensively utilized within piping networks of modern nuclear submarines and modern turbofan aero–engines where space limitation is considered a supreme concern. According the author’s knowledge, no shakedown analysis exists for such structure based on experimental data. In the current research, the pipe bend setup analyzed is subjected to a spectrum of steady internal pressures and cyclic out–of–plane bending moments. A previously developed direct non–cyclic simplified technique, for determining elastic shakedown limit loads, is utilized to generate the elastic shakedown boundary of the analyzed structure. Comparison with the elastic shakedown boundary of the same structure, but subjected to cyclic in–plane bending moments revealed a higher shakedown boundary for the out–of–plane bending loading configuration with a maximum bending moment ratio of 1.4 within the low steady internal pressure spectrum. The ratio decreases towards the medium to high internal pressure spectrum. The simplified technique outcomes showed excellent correlation with the results of full elastic–plastic cyclic loading finite element simulations.

Theoretical Analysis of the Stresses in Pipe Bends Subjected to Out-of-Plane Bending

1967 ◽  
Vol 9 (2) ◽  
pp. 115-123 ◽  
Author(s):  
R. T. Smith
Keyword(s):  
Theoretical Analysis ◽  
Digital Computer ◽  
Design Procedure ◽  
Theoretical Work ◽  
Theoretical Treatment ◽  
Bending Moments ◽  
Out Of Plane ◽  
Plane Bending ◽  
Comparison Of The Results ◽  
Maximum Stresses

Most of the experimental and theoretical work on the flexure of pipe bends has concerned bending in the plane of the bend but comparison of the results of some experiments using out-of-plane bending with calculations based on existing theories indicated a need for a more exact theoretical analysis of this form of loading. In this paper a comprehensive theoretical treatment of the elastic flexure of curved tubes already published for in-plane bending has been adapted to deal with out-of-plane bending. The equations for both forms of loading have been programmed for solution by a digital computer and a design procedure is suggested to find the maximum stresses due to combined in-plane, out-of-plane and torsional bending moments.

Structural Performance of Steel Pipe Tee-Junctions

2014 ◽  
Author(s):  
Theocharis Papatheocharis ◽  
Kalliopi Diamanti ◽  
George E. Varelis ◽  
Philip C. Perdikaris ◽  
Spyros A. Karamanos
Keyword(s):  
Internal Pressure ◽  
Low Cycle Fatigue ◽  
Axial Loading ◽  
Steel Pipe ◽  
Structural Performance ◽  
Finite Element Models ◽  
Bending Tests ◽  
Out Of Plane ◽  
Dimensional Measurements ◽  
Plane Bending

The behavior of steel pipe junctions (Tees) subjected to strong loading in the presence of internal pressure is examined in the present study. The analysis is based on a set of monotonic and cyclic out-of plane bending tests under constant and increasing amplitude displacement-controlled loading schemes leading to low-cycle fatigue failure. Rigorous finite element models are developed to support the experiments, accounting for detailed dimensional measurements and material testing results obtained prior to testing. A parametric analysis is also conducted focusing on the effect of the geometrical characteristics on the overall junction behavior. The performance of the Tee-junctions with varying geometries under out-of plane bending, in-plane bending and axial loading is also examined numerically accounting for the presence of internal pressure.

Effect of Bend Angle on Gross Plastic Deformation of Pipe Bends for Out-of-Plane Bending: A Study Using Plastic Work Curvature Method

2016 ◽  
Author(s):  
Anindya Bhattacharya ◽  
Sachin Bapat ◽  
Hardik Patel ◽  
Shailan Patel ◽  
Michael P. Cross
Keyword(s):  
Plastic Deformation ◽  
Internal Pressure ◽  
Bending Moment ◽  
Plastic Work ◽  
Bend Angle ◽  
Piping System ◽  
Plastic Collapse ◽  
Pipe Bend ◽  
Out Of Plane ◽  
Plane Bending

Bends are an integral part of a piping system. Because of the ability to ovalize and warp they offer more flexibility when compared to straight pipes. Piping Code ASME B31.3 [1] provides flexibility factors and stress intensification factors for pipe bends. Like any other piping component, one of the failure mechanisms of a pipe bend is gross plastic deformation. In this paper, plastic collapse load of pipe bends have been analyzed for various bend parameters (bend parameter = tRbrm2) under internal pressure and out-of-plane bending moment for various bend angles using both small and large deformation theories. FE code ABAQUS version 6.9EF-1 has been used for the analyses. The goal of the paper is to develop an expression for plastic collapse moment for a bend using plastic work curvature method when the bend is subjected to out-of-plane bending moment and internal pressure as a function of bend angle and bend parameter.

Design Procedure for Flexibility Factors of 90-Deg Curved Pipe Having Various Tangent Lengths (Design Paper)

1993 ◽  
Vol 115 (3) ◽  
pp. 319-324 ◽  
Author(s):  
D. J. Nordham ◽  
L. M. Kaldor
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Experimental Work ◽  
Design Procedure ◽  
Simple Design ◽  
Finite Element Analyses ◽  
Curved Pipe ◽  
Out Of Plane ◽  
Flexibility Factor ◽  
Design Paper

A simple design procedure, based on 175 finite element analyses, was derived to predict the flexibility factor due to an in-plane or out-of-plane moment for a 90-deg curved pipe with end constraints composed of tangents of any length terminated by rigid flanges and no internal pressure loads. The results of this design procedure were then compared to flexibility factors obtained from additional finite element analyses and experimental work. Flexibility factors calculated using the design equations in the Power Piping Code (ANSI/ASME B31.1-1986) were also compared to all finite element and experimental work. It was found that this design procedure more accurately predicts the flexibility factors than the Power Piping Code.

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