Inelastic Behavior of Threaded Piping Connections: Reconciliation of Experimental and Analytic Results

2011 ◽  
Author(s):  
Yonghee Ryu ◽  
Anahid Behrouzi ◽  
Tsega Melesse ◽  
Vernon C. Matzen
Keyword(s):  
Inelastic Behavior ◽  
Test Results ◽  
Element Analysis ◽  
Shell Elements ◽  
Rotational Spring ◽  
Beam Elements ◽  
Piping Systems ◽  
Threaded Joints ◽  
Rigid Connection ◽  
Euler Bernoulli Beam

Modeling the behavior of piping systems with threaded joints is difficult because the joints do not act as rigid connections. At one level of approximation the connection can be modeled as a semi-rigid connection using a rotational spring. This study modeled a straight pipe using either Euler-Bernoulli beam elements [4] or Finite Element Analysis (FEA) shell elements and a support condition using the rotational spring. Laboratory tests were conducted on 1 in. diameter specimens of black iron Schedule 40 pipe in a cantilever configuration. The specimen was loaded monotonically into the inelastic region. A Ramberg-Osgood model [5] was used to represent the rotational spring and the correlation between test results and analytical predictions was quite good.

Assessment of Interacting Corrosion Defects in Thin-Walled Pipes

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Ahmed A. Soliman ◽  
Mohammad M. Megahed ◽  
Ch. A. Saleh ◽  
Mostafa Shazly
Keyword(s):  
Nonlinear Finite Element ◽  
Metal Loss ◽  
Test Results ◽  
Defect Depth ◽  
Element Analysis ◽  
Shell Elements ◽  
Codes Of Practice ◽  
Useful Life ◽  
Corrosion Defects ◽  
Interaction Rule

Abstract Corrosion in pipes is usually found in the form of closely spaced defects, which eventually reduce the pipe pressure carrying capacity and piping planned useful life. Codes and standards have been developed to evaluate the effect of such form of metal loss on the piping pressure carrying capacities. However, predictions of such codes are usually conservative, and hence, there is a need to assess their degree of conservatism. The present paper utilizes nonlinear finite element analysis (FEA) in estimating pressure carrying capacities of defective pipes, and hence provides an evaluation of codes degree of conservatism. Shell elements with reduced thickness at the corrosion defect are adopted and their accuracy is assessed by comparison with those of solid elements as well as experimental test results. The influence of defects interaction is investigated by considering two neighboring defects in an inclined direction to each other. The influence of inclination angle, inclined proximity distance between the two defects, and the defect depth to wall thickness ratio are investigated. Comparisons were made with predictions of codes of practice in all cases. Code predictions were found to be conservative compared to FEA results. Furthermore, the interaction rule embedded in the codes for checking for interaction leads to inaccurate predictions for closely spaced defects as it does not include the effect of defect depth.

Modelling and Experimental Validation of a Novel Piezohydraulic Servovalve

2011 ◽  
Author(s):  
Dhinesh K. Sangiah ◽  
Andrew R. Plummer ◽  
Christopher R. Bowen ◽  
Paul Guerrier
Keyword(s):  
Electrical Power ◽  
Test Results ◽  
Bernoulli Beam ◽  
Element Analysis ◽  
First Order ◽  
Beam Analysis ◽  
Design Tradeoffs ◽  
Fast Flow ◽  
Euler Bernoulli Beam ◽  
Good Agreement

Servovalves are compact, accurate, fast flow modulating valves. However, cost reduction pressures exist, not least due to the electomagnetically actuated pilot stage. This paper describes a servovalve with a jet deflector pilot stage actuated by a multilayer piezoelectric bimorph. The electrical power and voltage requirements are relatively low (+/−30V), and mechanical spool feedback is used as opposed to the more complex electrical feedback alternative. A mathematical model of the valve is presented, which is used to simulate its performance. Finite element analysis is used to model the bimorph actuator and the feedback wire assembly to verify an Euler-Bernoulli beam analysis. A Moog 26 Series servovalve is used as a basis for the prototype. Experimental test results are in good agreement with the simulation results. The high order nonlinear model is also approximated by a first order transfer function to identify the parameters that dictate the main design tradeoffs.

Further Tests on Pipe Elements in Commercial Software for Nuclear Power Piping Analysis

2015 ◽  
Author(s):  
L. Zeng ◽  
A. Börjesson ◽  
L. G. Jansson
Keyword(s):  
Nuclear Power ◽  
Commercial Software ◽  
Pipe Bend ◽  
Shell Elements ◽  
Beam Elements ◽  
Numerical Tests ◽  
Pipe Model ◽  
Piping Systems ◽  
Reaction Forces ◽  
Element Computation

The paper reports our further numerical tests on pipe elements in some commercial software for nuclear power piping analysis. Following our earlier tests on pipe elements, numerical tests are conducted using ANSYS, ABAQUS and PIPESTRESS with focus on the accuracy and reliability of key solutions: eigen-frequencies, reaction forces, stresses in pipe bends, deformation and others due to both static and dynamic loads. Benchmark examples are considered: (1) A simple pipe bend with varying wall-thicknesses; (2) A pipe model with two bends; (3) An irregular pipe model. A comparison against computations using elbow and shell elements is reported. The results indicate that analyses using traditional beam elements can go wrong and cautions are necessary, which is of particular importance for cases when extreme flexible piping systems are dealt with. It is concluded that there is a great need for advanced finite element computation for achieving a more reliable and accurate piping analysis.

Analytical Seismic Fragility Analyses of Fire Sprinkler Piping Systems with Threaded Joints

2015 ◽  
Vol 31 (2) ◽  
pp. 1125-1155 ◽  
Author(s):  
Siavash Soroushian ◽  
Arash E. Zaghi ◽  
Manos Maragakis ◽  
Alicia Echevarria ◽  
Yuan Tian ◽  
...  
Keyword(s):  
San Francisco ◽  
Experimental Results ◽  
System Level ◽  
Seismic Fragility ◽  
Piping System ◽  
Inelastic Behavior ◽  
Demand Model ◽  
Piping Systems ◽  
Threaded Joints ◽  
Fire Sprinkler

For the first time, an analytical modeling methodology is developed for fire sprinkler piping systems and used to generate seismic fragility parameters of these systems. The analytical model accounts for inelastic behavior constituents of the system, including: threaded joints, solid braces, hangers, and restrainers. The model incorporates a newly developed hysteresis model for threaded tee joints that is validated by the experimental results of several tee subassemblies. The modeling technique at the subsystem level is validated by using the experimental results of a sprinkler piping system. The methodology is used to obtain the seismic response of the fire sprinkler piping system of University of California, San Francisco Hospital under a suite of 96 artificially generated triaxial floor acceleration histories. After the component fragility parameters are obtained for the components of the system, three system-level damage states are defined, and a joint probabilistic seismic demand model is utilized to develop system fragility parameters.

Finite Element Analysis of Reinforced Concrete Beams with Exterior FRP Shell

2011 ◽  
Vol 243-249 ◽  
pp. 1461-1465
Author(s):  
Chuan Min Zhang ◽  
Chao He Chen ◽  
Ye Fan Chen
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Test Results ◽  
Contact Interface ◽  
Accurate Calculation ◽  
Element Analysis

The paper makes an analysis of the reinforced concrete beams with exterior FRP Shell in Finite Element, and compares it with the test results. The results show that, by means of this model, mechanical properties of reinforced concrete beams with exterior FRP shell can be predicted better. However, the larger the load, the larger deviation between calculated values and test values. Hence, if more accurate calculation is required, issues of contact interface between the reinforced concrete beams and the FRP shell should be taken into consideration.

Vibration of Beam with Elastically Restrained Ends and Rotational Spring-Lumped Rotary Inertia System at Mid-Span

2015 ◽  
Vol 15 (02) ◽  
pp. 1450040 ◽  
Author(s):  
Seyed Mojtaba Hozhabrossadati ◽  
Ahmad Aftabi Sani ◽  
Masood Mofid
Keyword(s):  
Technical Note ◽  
Rotary Inertia ◽  
Mode Shapes ◽  
Bernoulli Beam ◽  
Mass System ◽  
Rotational Spring ◽  
Beam System ◽  
Sample Frequency ◽  
Elastically Restrained ◽  
Euler Bernoulli Beam

This technical note addresses the free vibration problem of an elastically restrained Euler–Bernoulli beam with rotational spring-lumped rotary inertia system at its mid-span hinge. The governing differential equations and the boundary conditions of the beam are presented. Special attention is directed toward the conditions of the intermediate spring-mass system which plays a key role in the solution. Sample frequency parameters of the beam system are solved and tabulated. Mode shapes of the beam are also plotted for some spring stiffnesses.

Some new results and current challenges in the finite element analysis of shells

Acta Numerica ◽  
2001 ◽  
Vol 10 ◽  
pp. 215-250 ◽  
Author(s):  
Dominique Chapelle
Keyword(s):  
Finite Element ◽  
Shell Theory ◽  
Shell Structures ◽  
Engineering Practice ◽  
Element Analysis ◽  
Shell Elements ◽  
Shell Models ◽  
The Finite Element Analysis ◽  
Shell Finite Element ◽  
Mathematical Analyses

This article, a companion to the article by Philippe G. Ciarlet on the mathematical modelling of shells also in this issue of Acta Numerica, focuses on numerical issues raised by the analysis of shells.Finite element procedures are widely used in engineering practice to analyse the behaviour of shell structures. However, the concept of ‘shell finite element’ is still somewhat fuzzy, as it may correspond to very different ideas and techniques in various actual implementations. In particular, a significant distinction can be made between shell elements that are obtained via the discretization of shell models, and shell elements – such as the general shell elements – derived from 3D formulations using some kinematic assumptions, without the use of any shell theory. Our first objective in this paper is to give a unified perspective of these two families of shell elements. This is expected to be very useful as it paves the way for further thorough mathematical analyses of shell elements. A particularly important motivation for this is the understanding and treatment of the deficiencies associated with the analysis of thin shells (among which is the locking phenomenon). We then survey these deficiencies, in the framework of the asymptotic behaviour of shell models. We conclude the article by giving some detailed guidelines to numerically assess the performance of shell finite elements when faced with these pathological phenomena, which is essential for the design of improved procedures.

Experimental and theoretical study of sandwich composites with Z-pins under quasi-static compression loading

2021 ◽  
pp. 136943322110073
Author(s):  
Erdem Selver ◽  
Gaye Kaya ◽  
Hussein Dalfi
Keyword(s):  
Vinyl Ester ◽  
Failure Modes ◽  
Critical Role ◽  
Sandwich Composites ◽  
Test Results ◽  
Compressive Properties ◽  
Element Analysis ◽  
Static Compression ◽  
Quasi Static Compression ◽  
Good Agreement

This study aims to enhance the compressive properties of sandwich composites containing extruded polystyrene (XPS) foam core and glass or carbon face materials by using carbon/vinyl ester and glass/vinyl ester composite Z-pins. The composite pins were inserted into foam cores at two different densities (15 and 30 mm). Compression test results showed that compressive strength, modulus and loads of the sandwich composites significantly increased after using composite Z-pins. Sandwich composites with 15 mm pin densities exhibited higher compressive properties than that of 30 mm pin densities. The pin type played a critical role whilst carbon pin reinforced sandwich composites had higher compressive properties compared to glass pin reinforced sandwich composites. Finite element analysis (FE) using Abaqus software has been established in this study to verify the experimental results. Experimental and numerical results based on the capabilities of the sandwich composites to capture the mechanical behaviour and the damage failure modes were conducted and showed a good agreement between them.

Finite Element Modeling of Unidirectional Non-Crimp Fabric for Manufacturing of Composites with Embedded Cabling

2013 ◽  
Vol 554-557 ◽  
pp. 484-491 ◽  
Author(s):  
Alexander S. Petrov ◽  
James A. Sherwood ◽  
Konstantine A. Fetfatsidis ◽  
Cynthia J. Mitchell
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Explicit Finite Element ◽  
Shell Elements ◽  
Beam Elements ◽  
Hybrid Finite Element ◽  
International Benchmarking ◽  
Unidirectional Glass ◽  
Forming Simulations

A hybrid finite element discrete mesoscopic approach is used to model the forming of composite parts using a unidirectional glass prepreg non-crimp fabric (NCF). The tensile behavior of the fabric is represented using 1-D beam elements, and the shearing behavior is captured using 2-D shell elements into an ABAQUS/Explicit finite element model via a user-defined material subroutine. The forming of a hemisphere is simulated using a finite element model of the fabric, and the results are compared to a thermostamped part as a demonstration of the capabilities of the used methodology. Forming simulations using a double-dome geometry, which has been used in an international benchmarking program, were then performed with the validated finite element model to explore the ability of the unidirectional fabric to accommodate the presence of interlaminate cabling.

Finite Element Analysis of Automobile Drive Axle Housing Based on ANSYS

2015 ◽  
Vol 741 ◽  
pp. 223-226
Author(s):  
Hai Bin Li
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Dynamic Performance ◽  
Element Analysis ◽  
Shell Elements ◽  
Fea Model ◽  
Automobile Design ◽  
Housing Structure ◽  
Drive Axle ◽  
Drive Axle Housing

The performance of automobile drive axle housing structure affects whether the automobile design is successful or not. In this paper, the author built the FEA model of a automobile drive axle housing with shell elements by ANSYS. In order to building the optimization model of the automobile drive axle housing, the author studied the static and dynamic performance of it’s structure based on the model.

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