On Pipe Elbow Elements in ABAQUS and Benchmark Tests

2014 ◽  
Author(s):  
Lingfu Zeng ◽  
Lennart G. Jansson ◽  
Yordan Venev
Keyword(s):  
Peak Stress ◽  
Coarse Mesh ◽  
Pipe Bend ◽  
Shell Elements ◽  
Finite Element Software ◽  
Pipe Elbow ◽  
Element Size ◽  
Benchmark Tests ◽  
Pipe Section ◽  
Insight Into

In this paper, elbow elements in commercial finite element software ABAQUS are reviewed and two commonly used elements, ELBOW31 (2-node, linear) and ELBOW32 (3-node, quadratic), are numerically tested for two Benchmark examples: a cantilever pipe and an in-plane bending pipe bend. Two main issues are studied through the numerical tests: (1) The effect of the element size and the number of ovalization modes chosen for computation; (2) The accuracy of computed deformation and stresses. To gain an insight into the behavior of these elements, a comparison against published results by experiment and computations using elbow elements in software ADINA and MARC, as well as computations using ABAQUS shell elements, is conducted. It is shown that: (i) these elements predict a good peak stress solution with a reasonably coarse mesh and 6 ovalization modes; (ii) the ovalization and the distribution of stresses predicted around the pipe section show, though using a relatively dense mesh, a notable difference as compared to solutions computed by ABAQUS shell elements; (iii) the ADINA elbow element seems to provide, though using a very coarse mesh, a solution closest to analytic and experimental results. It is concluded that there are great needs for in-depth studies on elbow elements regarding reliability and accuracy issues.

On Pipe Elements Currently Available for Nuclear Power Piping Analysis and Their Benchmark Tests

2012 ◽  
Author(s):  
Lingfu Zeng ◽  
Lennart G. Jansson
Keyword(s):  
Nuclear Power ◽  
Beam Theory ◽  
Complex Loading ◽  
Nuclear Regulatory Commission ◽  
General Purpose ◽  
Early Years ◽  
Shell Elements ◽  
Finite Element Software ◽  
Benchmark Tests ◽  
Regulatory Commission

In this paper, an overview is given for various pipe elements currently available in commercial general-purpose finite element software, such as ADINA, ANSYS and ABAQUS and several others, with respect to their formulations, applications and limitations. Throughout the overview, a comparison to piping analysis based on a usual 3-diemnsional beam theory, which appears in many software particularly developed in early years for piping analysis is made. Benchmark tests ranging from simple to relative complex nuclear piping systems, given by US Nuclear Regulatory Commission (NRC), are taken for addressing three key concerns in nuclear piping analysis: reliability, accuracy and effectivity. It is demonstrated that: (1) piping analysis using software developed purely based on traditional curved beam theory can go wrong; and (2) a reliable piping analysis, in particular, for complex loading conditions and non-linear applications, can only be achieved by using so-called pipe-shell elements.

Investigation into the Spall Strength of Cast Iron

2012 ◽  
Vol 13 (2) ◽  
pp. 195-199
Author(s):  
Gifford Plume ◽  
Carl-Ernst Rousseau
Keyword(s):  
Cast Iron ◽  
Spall Strength ◽  
Peak Stress ◽  
Small Scale ◽  
Spall Fracture ◽  
Gas Gun ◽  
Minimum Stress ◽  
Impact Experiments ◽  
Insight Into ◽  
Spall Failure

Abstract The spall strength of cast iron has been investigated by means of planar plate impact experiments conducted in a vacuum. A single stage gas gun was utilized to drive projectiles to velocities between 100 and 300 m/sec, resulting in low to moderate shock loading of the cast iron specimens. Measurement of the stress histories were made with the use of commercial manganin stress gauges that were imbedded between the back face of the cast iron specimen and a low impedance backing of polycarbonate. Spall strength values were calculated utilizing the measured peak stress and minimum stress pullback signals captured in the stress history. Spall Strength values were found to vary between 0.98 and 1.45 GPa for the cast iron tested. Post-Mortem analysis of recovered specimen has provided insight into the evolution of spall failure in cast iron and shed light on the varying nature of the spall strength values calculated. It was determined that the lower bound of strength values was associated with small scale micro-failure, while the upper bound values corresponded to complete spall fracture.

Treatment of Bending Deformations in Maritime Crash Analyses

2020 ◽  
Author(s):  
Mihkel Kõrgesaar ◽  
Martin Storheim
Keyword(s):  
Plane Stress ◽  
Control Element ◽  
Crash Analysis ◽  
Fracture Criteria ◽  
Shell Elements ◽  
Bending Deformation ◽  
Mechanical Field ◽  
Element Size ◽  
Inherent Nature ◽  
Element Erosion

Abstract This paper focuses on the bending deformation experienced by metallic materials and its characterization during the crash analysis of ship structures. These analyses are conducted with plane stress shell elements for computational reasons. The inherent nature of through thickness plane stress poses restrictions on how the bending associated stress and strain distribution are resolved. Namely, fracture criteria used in crash analysis account bending damage accumulation differently. Most criteria do not specifically address the issue as element erosion is activated once all through thickness integration points have reached the predefined failure condition. However, when elements are bent, material layers (top and bottom) display strong variations in mechanical field variables that are commonly used to control element deletion. Therefore, the focus of current analyses is to show how different fracture criteria account bending deformation and how sensitive are the results depending on the chosen element size.

Locking Behavior of Isoparametric Curved Beam Finite Elements

1995 ◽  
Vol 48 (11S) ◽  
pp. S25-S29 ◽  
Author(s):  
Miguel Luiz Bucalem ◽  
Klaus-Ju¨rgen Bathe
Keyword(s):  
Shell Element ◽  
Beam Element ◽  
Curved Beam ◽  
Shear Locking ◽  
Shell Elements ◽  
One Dimensional ◽  
Curved Beam Element ◽  
The One ◽  
Insight Into ◽  
The Continuum

We present a study of the membrane and shear locking behavior in an isoparametric curved beam element. The objective is to gain insight into the locking phenomenon, specially membrane locking, of continuum based degenerated shell elements. This is possible since the isobeam element is the one-dimensional analogue of the continuum based shell element. In this context, reduced integration and mixed interpolation schemes are briefly examined. Such a study can be a valuable aid when developing new shell elements.

Investigation into the Spall Strength of Cast Iron

2012 ◽  
Vol 13 (2) ◽  
Author(s):  
Gifford Plume ◽  
Carl-Ernst Rousseau
Keyword(s):  
Cast Iron ◽  
Spall Strength ◽  
Peak Stress ◽  
Small Scale ◽  
Spall Fracture ◽  
Gas Gun ◽  
Minimum Stress ◽  
Impact Experiments ◽  
Insight Into ◽  
Spall Failure

AbstractThe spall strength of cast iron has been investigated by means of planar plate impact experiments conducted in a vacuum. A single stage gas gun was utilized to drive projectiles to velocities between 100 and 300 m/sec, resulting in low to moderate shock loading of the cast iron specimens. Measurement of the stress histories were made with the use of commercial manganin stress gauges that were imbedded between the back face of the cast iron specimen and a low impedance backing of polycarbonate. Spall strength values were calculated utilizing the measured peak stress and minimum stress pullback signals captured in the stress history. Spall Strength values were found to vary between 0.98 and 1.45 GPa for the cast iron tested. Post-Mortem analysis of recovered specimen has provided insight into the evolution of spall failure in cast iron and shed light on the varying nature of the spall strength values calculated. It was determined that the lower bound of strength values was associated with small scale micro-failure, while the upper bound values corresponded to complete spall fracture.

A Simple and Effective Pipe Elbow Element—Linear Analysis

1980 ◽  
Vol 47 (1) ◽  
pp. 93-100 ◽  
Author(s):  
K. J. Bathe ◽  
C. A. Almeida
Keyword(s):  
Radial Displacement ◽  
Linear Analysis ◽  
Pipe Bend ◽  
Pipe Elbow ◽  
Von Karman ◽  
Displacement Based ◽  
Von Kármán ◽  
Displacement Patterns ◽  
Bend Element

The formulation of a new, simple, and effective displacement-based pipe bend element is presented. The displacement assumptions are axial, torsional, and bending displacements that vary cubically along the axis of the elbow with plane sections remaining plane, and a generalization of the von Karman pipe radial displacement patterns to include the ovalization effects. The amount of ovalization varies cubically along the elbow with full compatibility between elbows. The pipe bend element has been implemented, and the results of various sample analyses are presented, which illustrate the effectiveness of the element.

Shell Elements Performance in Crashworthiness Analysis

2004 ◽  
Author(s):  
Shen Rong Wu ◽  
Nripen Saha ◽  
Ping Chen
Keyword(s):  
Finite Element ◽  
Lower Order ◽  
High Speed ◽  
Explicit Finite Element ◽  
Shell Elements ◽  
High Speed Impact ◽  
Finite Element Software ◽  
Refined Meshes ◽  
Triangular Elements ◽  
Crashworthiness Analysis

Crashworthiness analysis, a type of large deformation transient dynamics, has been an important and active area of researches and engineering applications. Several shell elements have been implemented in the finite element software for crashworthiness analysis. Among them, the 4-node quadrilateral Belytschko-Tsay element, using lower order integration technique is most commonly employed, due to its efficiency, robustness and overall accuracy. However, the lower order integration brings in some uncertainty. This paper is to conduct an engineering evaluation on performance of various shell elements, including Belytschko-Tsay, Belytschko-Leviathan (QPH), Bathe-Dvorkin, discrete Kirchhoff triangular elements, available in the commercial explicit finite element software. The study uses several linear and nonlinear benchmark examples and high-speed impact examples, to investigate the performance of these elements. Results of engineering interest and efficiency of computation are reported. Also, the behavior of finite element convergence, observed from the results by a sequence of refined meshes is investigated.

Pipe Bend Analysis by Thin Shell Theory

1986 ◽  
Vol 53 (1) ◽  
pp. 173-180 ◽  
Author(s):  
J. F. Whatham
Keyword(s):  
Computer Program ◽  
Thin Shell ◽  
Shell Theory ◽  
Factor Versus ◽  
Pipe Bend ◽  
Pipe Elbow ◽  
Wide Range ◽  
Out Of Plane ◽  
Plane Bending ◽  
Thin Shell Theory

Thin shell theory is applied to pipe bends terminated by flanges or flange-ended tangent pipes and subjected to any end loading, either in-plane or out-of-plane. Graphs of flexibility factor versus pipe bend characteristic are presented for in-plane bending of a wide range of pipe elbows terminated by flanges or short flange-ended tangents. Experimental results verify the thin shell solutions for in-plane and out-of-plane bending of a flanged pipe elbow. The capabilities of a computer program BENDPAC are also described.

On the Structural Design of Tubular Joints

1975 ◽  
Vol 97 (2) ◽  
pp. 391-399 ◽  
Author(s):  
W. Visser
Keyword(s):  
Stress Concentration ◽  
Structural Design ◽  
Stress Distributions ◽  
Membrane Action ◽  
Shell Elements ◽  
Tubular Joints ◽  
Tubular Joint ◽  
Offshore Industry ◽  
Insight Into ◽  
Good Agreement

Stresses in thin-walled tubular joints can be calculated with finite-element computer programs that employ ‘thin-shell’ elements. Such a program, designated SATE, has been developed specifically with the object of determining stress distributions in complex tubular joints as generally encountered in the offshore industry. The program has been applied to several joint geometries and good agreement has been observed between experimental and calculated results. The program thus provides insight into the structural design of tubular joints. Using the SATE program, the influence of changes in design of both unstiffened and stiffened tubular joints on the stress-concentration factor has been studied. In this context, the current API recommendations for simple tubular joint design are discussed. Calculations have demonstrated that in the design of large tubular joints, allowance should be made for membrane action rather than for bending of the chord and brace walls. Such an approach leads to joints of low stress concentration.

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