scholarly journals Experimental and Numerical Investigation of Plain and Gouged Dents in Steel Pipes Subjected to Pressure and Moment Loading

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
J. Błachut ◽  
I. B. Iflefel
Keyword(s):  
Finite Element ◽  
Mild Steel ◽  
Numerical Investigation ◽  
Test Data ◽  
Experimental Test ◽  
Bending Moment ◽  
Diameter Ratio ◽  
Steel Pipes ◽  
Outside Diameter ◽  
Good Agreement

Six laboratory scale, mild steel pipes with the outside diameter-to-wall-thickness ratio, Do∕t≅40, were dented to about 15–20% of outside diameter Do, by a hemispherical indenter with its diameter to pipe’s outside diameter ratio, 2a∕Do≅0.41. Three pipes had surface gouges running axially in them, and the remaining three were gouge free. Five of them were then collapsed by a bending moment followed by pressure burst tests. Experimental test data has been used to benchmark the finite element results, details of which are given in this paper. Good agreement between experimental and numerical results was obtained in the modeling of denting, but not so well in the modeling of bending—indicating the need for further work in order to address the discrepancies.

Analysis of Plain and Gouged Dents in Steel Pipes Subjected to Pressure and Moment Loading

2006 ◽  
Author(s):  
J. Blachut ◽  
I. B. Iflefel
Keyword(s):  
Mild Steel ◽  
Test Data ◽  
Wall Thickness ◽  
Experimental Test ◽  
Bending Moment ◽  
Diameter Ratio ◽  
Numerical Results ◽  
Steel Pipes ◽  
Outside Diameter ◽  
Good Agreement

Six laboratory scale, mild steel pipes with the outside diameter-to-wall-thickness ratio, Do/t ≅ 40, were dented to about 15%–20% of outside diameter Do, by a hemispherical indenter with its diameter to pipe’s outside diameter ratio, d/Do ≅ 0.41. Three pipes had surface gouges running axially in them, and the remaining three were gouge-free. Five of them were then collapsed by a bending moment followed by pressure burst tests. Experimental test data has been used to benchmark the FE results, details of which are given in the paper. Good agreement between experimental and numerical results was obtained.

Response of Mild Steel Pipes Under High Mass Low Velocity Impacts

2014 ◽  
Author(s):  
Shamsoon Fareed ◽  
Ian May
Keyword(s):  
Finite Element ◽  
Mild Steel ◽  
Impact Energy ◽  
High Mass ◽  
Low Velocity ◽  
Element Analysis ◽  
Steel Pipes ◽  
Impact Tests ◽  
The Finite Element Analysis ◽  
The Impact

Accidental loads, for example, due to heavy dropped objects, impact from the trawl gear and anchors of fishing vessels can cause damage to pipelines on the sea bed. The amount of damage will depend on the impact energy. The indentation will be localized at the contact area of the pipe and the impacting object, however, an understanding of the extent of the damage due to an impact is required so that if one should occur in practice an assessment can be made to determine if remedial action needs to be taken to ensure that the pipeline is still serviceable. There are a number of parameters, including the pipe cross section and impact energy, which influence the impact behaviour of a pipe. This paper describes the response, and assesses the damage, of mild steel pipes under high mass low velocity impacts. For this purpose full scale impacts tests were carried out on mild steel pipe having diameter of 457 mm, thickness of 25.4 mm and length of 2000 mm. The pipe was restrained along the base and a 2 tonnes mass with sharp impactor having a vertical downward velocity of 3870 mm/sec was used to impact the pipe transversely with an impact energy of 16 kJ. It was found from the impact tests that a smooth indentation was produced in the pipe. The impact tests were then used for validation of the non-linear dynamic implicit analyses using the finite element analysis software ABAQUS. Deformations at the impact zone, the rebound velocity, etc, recorded in the tests and the results of the finite element analysis were found to be in good agreement. The impact tests and finite element analyses described in this paper will help to improve the understanding of the response of steel pipes under impact loading and can be used as a benchmark for further finite element modelling of impacts on pipes.

Failure of Thin-Walled Pipes With D/T up to 140 and Conclusions for the Design Codes

2016 ◽  
Author(s):  
Henry Schau ◽  
Lilit Mkrtchyan ◽  
Michael Johannes
Keyword(s):  
Yield Stress ◽  
Bending Moment ◽  
Bending Stress ◽  
Dynamic Analyses ◽  
Asme Code ◽  
Stress Intensification Factor ◽  
Thin Walled ◽  
The Moment ◽  
Outside Diameter ◽  
Good Agreement

The influence of imperfections on the instability bending moment of thin-walled straight pipes with D/t-ratios (D - outside diameter, t - wall thickness) up to 140 is determined using nonlinear Finite Element (FE) analyses. The analyses show that the type and size of the imperfection, the D/t ratio and the material properties have significant influences on the instability moment. The nominal bending stress of pipes (yield stress 500 MPa) with D/t > 70 and an ovality of 0.5% is smaller than the yield stress at the instability point. That means, the failure occurs by buckling in the elastic range of the nominal bending stress. In static analyses the moment decreases abruptly after reaching the instability moment. In the dynamic analyses the pipe jumps abruptly to the state with smaller moment. The obtained results are applied to calculate the B2 index for pipes with D/t ≤ 140. The B2 indices for thin-walled straight pipes with D/t > 40 are considerably higher than 1.0. In general, there is a good agreement between the calculated B2 values and the values of the ASME Code. A correction factor for higher temperatures is not necessary. The allowable moments calculated with the B2 index and the stress intensification factor i are compared. The bending moments from disabled thermal expansion and anchor movements have the same effect on the failure due to (plastic) buckling as the primary moments and must be taken into account.

scholarly journals Study on the characteristics of pipe buckling strength under pure bending and external stress using nonlinear finite element analysis

2021 ◽  
Vol 12 (2) ◽  
pp. 110-116
Author(s):  
Hartono Yudo ◽  
Wilma Amiruddin ◽  
Ari Wibawa Budi Santosa ◽  
Ocid Mursid ◽  
Tri Admono
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Bending Moment ◽  
Nonlinear Finite Element Analysis ◽  
External Pressure ◽  
Diameter Ratio ◽  
Nonlinear Finite Element ◽  
Pure Bending ◽  
Element Analysis ◽  
Buckling Strength

Buckling and collapse are important failure modes for laying and operating conditions in a subsea position. The pipe will be subjected to various kinds of loads, i.e., bending moment, external pressure, and tension. Nonlinear finite element analysis was used to analyze the buckling strength of the pipe under pure bending and external pressure. The buckling of elastic and elasto-plastic materials was also studied in this work. The buckling strength due to external pressure had decreased and become constant on the long pipe when the length-to-diameter ratio (L/D) was increased. The non-dimensional parameter (β), which is proportionate to (D/t) (σy/E), is used to study the yielding influence on the buckling strength of pipe under combined bending and external pressure loading. The interaction curves of the buckling strength of pipe were obtained, with various the diameter-to-thickness ratio (D/t) under combination loads of external pressure and bending moment. For straight pipes L/D = 2.5 to 40, D = 1000 to 4000 mm, and D/t = 50 to 200 were set. The curved pipes D/t = 200, L/D =2.5 to 30 have been investigated by changing the radius of curvature-to-diameter ratio (R/D) from 50 to ∞, for each one. With decreasing R/D, the buckling strength under external pressure decreases slightly. This is in contrast to the bending of a curved pipe. When the value of R/D was decreased, the flexibility of the pipe was increased. However, the buckling strength of the pipe during bending was decreased due to the oval deformation at the cross-section.

Finite Element Stress Analysis and Strength Evaluation of Adhesive Butt Joints of Circular Pipes Combining Coupling Collar With Adhesive Subjected to Internal Pressure, Temperature Change and External Bending Moments

2004 ◽  
Author(s):  
Masahide Katsuo ◽  
Toshiyuki Sawa
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Temperature Change ◽  
Joint Strength ◽  
Bending Moment ◽  
Bending Moments ◽  
Stress Distributions ◽  
Butt Joints ◽  
Circular Pipes ◽  
Good Agreement

The interface stress distributions between the coupling collar, the adhesive and the pipes of the joint subjected to an internal pressure, a temperature change and bending moments are analyzed by using the elastic finite element method (FEM). The experiment of the rupture test of the joints manufactured by pipes made of structural steel (S45C, JIS) and epoxide adhesive was carried out by applying the above loads to the joints. From the numerical calculations, the following results were obtained: (1) the stress distributes uniformly at the interface except near the edges, (2) the stress becomes singular at the edges of the interfaces and (3) the stress distribution at a half part of the interface increase as the external bending moments increase and also Young’s modulus of the adhesive increases. From the experiments, the following results were obtained: (1) the joint strength (evaluated as a 95% non-rupture probability) under both the internal pressure and the temperature change increases as the coupling length increases and (2) the joint strength under both the internal pressure and the temperature change decreases when the external bending moment is applied to the joint. Furthermore, the numerical results are in fairly good agreement with the experimental results.

Limit Load of Pressurized Cylinder-Nozzle Intersection Using Finite Element Method

2016 ◽  
Vol 853 ◽  
pp. 276-280
Author(s):  
Xiao Hui Chen ◽  
Shi Yuan Liu ◽  
Tao Hu ◽  
Dong Xue Pei
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress Concentration ◽  
Pressure Vessel ◽  
Branch Pipe ◽  
Bending Moment ◽  
Plastic Limit ◽  
Plane Bending ◽  
Outside Diameter ◽  
Element Method

Pressure vessel contained with different nozzles which caused geometric discontinuity of the pressure vessel wall, which resulted in stress concentration around the nozzle. There may be the chances of failure of vessel junction, which was attributed to the high stress concentration. Therefore, detail stress distribution analysis need to be done for pressure vessel with the nozzle. Determination of limit pressure at different location on lateral nozzle by using finite element method. Lateral nozzle was subjected to internal pressure and in-plane bending moment. Results found that plastic hinge occurred in the nozzle-vessel junction area shoulder. Plastic limit loading increased with the increasing of outside diameter and wall thickness of branch pipe when the size of primary piping was constant value, whereby the influence of outside diameter of branch pipe was more remarkable. Moreover, engineering estimation formulas of plastic limit in-plane bending moment was obtained based on plastic limit loading database.

Modeling of the Rate Responsive Behavior of Elastomer Foam Materials

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Feixia Pan
Keyword(s):  
Finite Element ◽  
Constitutive Model ◽  
Test Data ◽  
Experimental Test ◽  
Strain Rates ◽  
Foam Material ◽  
Material Models ◽  
Rate Dependent ◽  
Responsive Behavior ◽  
Rate Responsive

Elastomer foam materials are shock absorbers that have been extensively used in applications of electronic packaging. Finite element modeling simulation plays an important role in helping the designers determine the best elastomer foam material and the best structure of a shock absorber. Elastomer foam materials have very complicated material behaviors. The prediction of the rate responsive behavior is one of the most interesting topics in elastomer material modeling. The focus of this article is to present a unique method for deriving the rate dependent constitutive model of an elastomer foam based on the extension of the Cowper and Symond law and the curve fitting on experimental test data. The research on rate dependent material models and the material models available in commercially available finite element analysis software have been reviewed. Test data collection at various strain rates has been discussed. Two steps of curve fitting on experimental test data are used to retrieve analytical expression of the constitutive model. The performance of the constitutive model for a foam material has been illustrated and shown to be quite good. This method is easy to understand and the simple formulation of the constitutive model is very suitable for applications in numerical simulation. The constitutive model could be used to predict the stress-strain curves of a foam material at any strain rate, especially at the intermediate strain rates, which are the most difficult to collect so far. In addition, this model could be readily integrated with the hyperelastic material models to more efficiently evaluate the mechanical behavior of an elastomer foam material. The model could potentially be implemented in commercially available software such as ABAQUS and LS-DYNA. The method presented is also useful in deriving constitutive models of rubberlike elastomer materials.

Effects of Geometric Imperfection on Bending Capacity of X80 Linepipe

2006 ◽  
Author(s):  
Nobuhisa Suzuki ◽  
Joe Kondo ◽  
Shigeru Endo ◽  
Nobuyuki Ishikawa ◽  
Mitsuhiro Okatsu ◽  
...  
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Finite Element Modeling ◽  
Bending Test ◽  
Moment Capacity ◽  
Geometric Imperfection ◽  
Bending Capacity ◽  
The Moment ◽  
Outside Diameter ◽  
Good Agreement

Validation of finite element modeling to predict bending capacity of linepipes and effects of geometric imperfection on the bending capacity are presented. A bending test of an X80 linepipe was conducted to discuss the validation and investigate the effects. The geometric imperfection of the linepipe about the outside diameter, the wall thickness and the longitudinal blister of the linepipe was measured in the round. Consequently, the results obtained by FEA taking into account the geometric imperfection present good agreement with the experimental data. And the moment capacity is virtually independent of the geometric imperfection however the strain capacity of the linepipe is quite susceptible to the geometric imperfection.

Lateral Loading of Internally Pressurized Steel Pipes

2006 ◽  
Vol 129 (4) ◽  
pp. 630-638 ◽  
Author(s):  
Arnold M. Gresnigt ◽  
Spyros A. Karamanos ◽  
Kyros P. Andreadakis
Keyword(s):  
Finite Element ◽  
Finite Elements ◽  
Internal Pressure ◽  
Lateral Loading ◽  
Two Dimensional ◽  
Heuristic Model ◽  
Steel Pipes ◽  
Nonlinear Shell ◽  
Model Equations ◽  
Good Agreement

This paper examines the denting response of pipes subjected to lateral (transverse) quasistatic wedge loading, in the presence of internal pressure. Pipes are modeled with nonlinear shell finite elements and a simplified analytical model. The analysis focuses on the significant influence of internal pressure on the denting resistance. Furthermore, the effects of wedge denting device orientation on the denting resistance are briefly discussed. Motivated by the experimental and numerical results, a two-dimensional heuristic model is proposed, which yields closed-form expressions for the denting force in terms of the corresponding displacement. The finite element results and the model equations are in good agreement with the experimental results and illustrate pipe denting response in an elegant manner.

Sign in / Sign up

Export Citation Format

Share Document