Analysis of Tubular Connections Using a Thin Cylinder Approximation—Part I

1983 ◽  
Vol 105 (4) ◽  
pp. 560-566
Author(s):  
P. D. Pattillo
Keyword(s):  
Finite Element ◽  
Stress State ◽  
Plastic Material ◽  
Material Behavior ◽  
Finite Element Analyses ◽  
Interference Fit ◽  
Thin Cylinder ◽  
Simple Tool ◽  
Cylinder Model ◽  
Approximate Equations

In the first part of this two-part study, approximate equations for determining the stress state in an interference fit connection are derived. The relations presented are based on a thin cylinder approximation and include the possibility of both elastic and plastic material behavior. Comparisons of the accuracy of the results to previous elastic and finite element analyses are presented, resulting in the conclusion that the thin cylinder model provides a useful, yet simple tool for determining bearing pressure over the majority of the engaged thread region.

Review and Comparison of Buckling Methodologies for ASME B&PV Code Linear Piping and Component Restraints

2017 ◽  
Author(s):  
Phillip Wiseman ◽  
Zara Z. Hoch ◽  
Shrikant S. Nargund
Keyword(s):  
Finite Element ◽  
Large Deformation ◽  
Plastic Material ◽  
Slenderness Ratio ◽  
Beam Theory ◽  
Euler Method ◽  
Buckling Load ◽  
Material Behavior ◽  
Finite Element Analyses ◽  
Deformation Method

Piping and component restraints are required to follow the design requirements as mentioned in ASME Boiler and Pressure Vessel Code, Section III, Subsection NF. One of the requirements indicates the necessity of calculating the critical buckling stresses for the members that are subjected to a compressive loading. This paper discusses the prescribed requirements in the Code that specifically address the considerations of the stability and buckling load capacities of linear piping and component restraints (i.e., struts). The finite element modeling of various strut geometries and the results of the buckling analyses of slender structural members (slenderness ratio, Kl/r, greater than or equal to 100) using various finite element solution techniques are presented herein. Specifically, three types of finite element analyses are conducted in an effort to define the critical buckling load for the subject structural member. These three finite element analyses include the traditional linear (Eigen value) Euler method; the nonlinear, second order large deformation method; and finally, the nonlinear large deformation method that incorporates nonlinear elastic-plastic material behavior. Additionally, two closed form solutions using strain energy method and Euler-Bernoulli beam theory are conducted on the same strut geometries. The results obtained from the aforementioned techniques are then compared both numerically and qualitatively with an appropriate explanation of the purpose and usefulness of each particular result with respect to the intent of the ASME B&PV Code, Section III, Subsection NF requirements. The results show significant variations based on differences in the assumptions and techniques employed in the respective analyses and simply applying the identical margin of safety to each technique does not yield consistent outcomes. As a result of the discussion we get an insight about the axial compression allowable stress equations and factors as defined in the ASME B&PV Code and how they should be refined depending on the type of buckling analysis we choose to conduct.

Shakedown Limit Load Determination for a Kinematically Hardening 90-Degree Pipe Bend Subjected to Constant Internal Pressure and Cyclic Bending

2007 ◽  
Author(s):  
Hany F. Abdalla ◽  
Mohammad M. Megahed ◽  
Maher Y. A. Younan
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Plastic Material ◽  
Kinematic Hardening ◽  
Limit Load ◽  
Material Behavior ◽  
Pipe Bend ◽  
Cyclic Bending ◽  
Perfectly Plastic ◽  
Shakedown Limit

A simplified technique for determining the shakedown limit load of a structure employing an elastic-perfectly-plastic material behavior was previously developed and successfully applied to a long radius 90-degree pipe bend. The pipe bend is subjected to constant internal pressure and cyclic bending. The cyclic bending includes three different loading patterns namely; in-plane closing, in-plane opening, and out-of-plane bending moment loadings. The simplified technique utilizes the finite element method and employs small displacement formulation to determine the shakedown limit load without performing lengthy time consuming full cyclic loading finite element simulations or conventional iterative elastic techniques. In the present paper, the simplified technique is further modified to handle structures employing elastic-plastic material behavior following the kinematic hardening rule. The shakedown limit load is determined through the calculation of residual stresses developed within the pipe bend structure accounting for the back stresses, determined from the kinematic hardening shift tensor, responsible for the translation of the yield surface. The outcomes of the simplified technique showed very good correlation with the results of full elastic-plastic cyclic loading finite element simulations. The shakedown limit moments output by the simplified technique are used to generate shakedown diagrams of the pipe bend for a spectrum of constant internal pressure magnitudes. The generated shakedown diagrams are compared with the ones previously generated employing an elastic-perfectly-plastic material behavior. These indicated conservative shakedown limit moments compared to the ones employing the kinematic hardening rule.

Determination of Fracture Toughness for Metal/Polymer Interfaces

1999 ◽  
Vol 121 (4) ◽  
pp. 275-281 ◽  
Author(s):  
V. Sundararaman ◽  
S. K. Sitaraman
Keyword(s):  
Fracture Toughness ◽  
Finite Element ◽  
Release Rate ◽  
Critical Energy ◽  
Material Behavior ◽  
Finite Element Analyses ◽  
Critical Energy Release Rate ◽  
Linear Elastic Material ◽  
Linear Elastic ◽  
Metal Polymer

This work focuses on the interpretation of experimental results obtained from fracture toughness tests conducted for a typical metal/polymer bimaterial interface similar to those encountered in electronic packaging applications. Test specimens with pre-implanted interfacial cracks were subjected to a series of fracture toughness tests. Interfacial fracture toughness is interpreted from the experimental results as the critical energy release rate (Gc) at the instant of crack advance. The values of Gc from the experiments are determined using direct data reduction methods assuming linear elastic material behavior. These Gc values are compared to critical energy release rate values predicted by closed-from analyses of the tests, and to critical J-integral values obtained from finite-element analyses of the test specimen geometries. The closed-form analyses assume linear elastic material behavior, while the finite-element analyses assume both linear elastic as well as elastic-plastic material behaviors.

Interference Fit Stress Concentrations with Full Chamfered Hub

2013 ◽  
Vol 572 ◽  
pp. 209-212 ◽  
Author(s):  
Juan Carlos Pérez-Cerdán ◽  
Miguel Lorenzo ◽  
Carmen Blanco
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress State ◽  
Quantitative Determination ◽  
Numerical Simulations ◽  
Not Given ◽  
The Finite Element Method ◽  
Stress Concentrations ◽  
Interference Fit

Quantitative determination of stress concentrations factors (SCF) in interference fits joints is highly relevant since they are not given by the theory of pressure cylinders commonly used for designing them. We study the capability of using a full chamfered hub as a geometrical design for reducing SCF. Stresses distributions and stresses concentrations factors are analyzed as a function of parameters that define the hub geometry with the aim of optimizing the design of proposed modified hubs. To achieve this goal, diverse numerical simulations by means of the finite element method (FEM) were carried out in order to quantitatively estimate the stress state existing at hub-shaft interface.

Review and Comparison of Buckling Methodologies for ASME B&PV Code, Section III, Subsection NF Linear Piping Restraints

2016 ◽  
Author(s):  
Shrikant Nargund ◽  
Dennis K. Williams
Keyword(s):  
Finite Element ◽  
Large Deformation ◽  
Plastic Material ◽  
Slenderness Ratio ◽  
Structural Member ◽  
Buckling Load ◽  
Material Behavior ◽  
Deformation Method ◽  
Critical Buckling Load ◽  
Hexahedral Elements

Piping supports and restrains are required to follow the design requirements as mentioned in ASME B&PV Code, Section III, Subsection NF. One of the requirements indicates the necessity of calculating the critical buckling stresses for the members that are subjected to a compressive loading. This paper discusses the prescribed requirements in the Code that specifically address the considerations of the stability and buckling load capacities of linear piping restraints (i.e., struts). The finite element modeling of various strut geometries and the results of the buckling analyses of a slender (slenderness ratio Kl/r greater than or equal to 100) structural members using various finite element solution techniques are presented herein. Specifically, three types of finite element analysis are conducted in an effort to define the critical buckling load for the subject structural member, and include the traditional linear (Eigen value) Euler method; the nonlinear, second order large deformation method; and finally, the nonlinear large deformation method that incorporates nonlinear elastic-plastic material behavior. These techniques are employed for a hollow cylindrical structural member (i.e., a strut assembly) with varying cross sections along its length. Finite element model consists of three dimensional hexahedral elements in combination with beam elements for the general purpose a finite element solver ANSYS. The critical buckling load is calculated in each case, thereby predicting the load at which instability will occur in the structural member. The results obtained from the aforementioned techniques are then compared both numerically and qualitatively with an appropriate explanation of the purpose and usefulness of each particular result with respect to the intent of the ASME B&PV Code, Section III, Subsection NF requirements. The results show significant variations (as expected) based on differences in the assumptions and techniques employed in the respective analyses.

Texture Based Finite Element Simulation of a Two-Step Can Forming Process

2012 ◽  
Vol 504-506 ◽  
pp. 655-660 ◽  
Author(s):  
Vedran Glavas ◽  
Thomas Böhlke ◽  
Dominique Daniel ◽  
Christian Leppin
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Plastic Material ◽  
Large Strain ◽  
Material Model ◽  
Material Behavior ◽  
Flow Rule ◽  
Forming Process ◽  
Aluminum Sheets ◽  
Element Simulation

Aluminum sheets used for beverage cans show a significant anisotropic plastic material behavior in sheet metal forming operations. In a deep drawing process of cups this anisotropy leads to a non-uniform height, i.e., an earing profile. The prediction of this earing profiles is important for the optimization of the forming process. In most cases the earing behavior cannot be predicted precisely based on phenomenological material models. In the presented work a micromechanical, texture-based model is used to simulate the first two steps (cupping and redrawing) of a can forming process. The predictions of the earing profile after each step are compared to experimental data. The mechanical modeling is done with a large strain elastic visco-plastic crystal plasticity material model with Norton type flow rule for each crystal. The response of the polycrystal is approximated by a Taylor type homogenization scheme. The simulations are carried out in the framework of the finite element method. The shape of the earing profile from the finite element simulation is compared to experimental profiles.

Computational and Experimental Study of Temperature Distribution and Residual Stress in Butt-Joint TIG Welds

2011 ◽  
Vol 480-481 ◽  
pp. 459-465
Author(s):  
Kuang Hung Tseng ◽  
Kuan Lung Chen
Keyword(s):  
Experimental Data ◽  
Residual Stress ◽  
Finite Element ◽  
Temperature Distribution ◽  
Finite Element Model ◽  
Power Distribution ◽  
Plastic Material ◽  
Element Model ◽  
Butt Joint ◽  
Material Behavior

This work conducted a non-linear finite element model associated with arc efficiency to simulate the temperature distribution and residual stress. A three-dimensional finite element analysis of temperature and stress in butt-joint TIG welds was performed using commercial software ANSYS. This model includes adjusting Gaussian distribution heat flux, alternating temperature dependent material properties, and managing thermal elasto-plastic material behavior. Computational results for both the temperature distribution and the residual stress are compared with available experimental data to confirm the accuracy of this technique. The simulated results of temperature distribution and residual stress are in good agreement with corresponding experimental data. The greatest value of this work does not lie in its ability to predict the magnitude and distribution of weld temperature and residual stress. Rather, this work proposed that prediction errors in a finite element model can be eliminated by modifying the arc power distribution function.

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