Development of J-Integral Solutions for Semi-Elliptical Circumferential Cracked Pipes Subjected to Internal Pressure and Bending Moment

2015 ◽  
Author(s):  
Makoto Udagawa ◽  
Jinya Katsuyama ◽  
Yoshihito Yamaguchi ◽  
Yinsheng Li ◽  
Kunio Onizawa
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Loading Condition ◽  
Bending Moment ◽  
J Integral ◽  
Surface Cracks ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Piping Systems ◽  
Integral Solutions

The J-integral solutions for cracked pipes are important in crack growth calculation and failure evaluation based on the elastic-plastic fracture mechanics. One of the most important crack types in structural integrity assessment for nuclear piping systems is circumferential semi-elliptical surface crack on the inside of the pipes. Although several J-integral solutions have been provided, no solutions were developed at both the deepest and the surface points of circumferential semi-elliptical surface cracks in pipes. In this study, with backgrounds described above, the J-integral solutions of circumferential semi-elliptical surface cracks on the inside of the pipe were developed by numerical finite element analyses. Three dimensional elastic-plastic analyses were performed considering different material properties, pipe sizes, crack dimensions and, especially, combined loading condition of internal pressure and bending moment which is a typical loading condition for nuclear piping systems. The J values at both the deepest and the surface points were extracted from finite element analysis results. Moreover, in order to benefit users in practical applications, a pair of convenient J-integral estimation equations were developed based on the calculated J values at the deepest and the surface points. Finally, the accuracy and applicability of the convenient equations were confirmed by comparing with the provided stress intensity factor solutions in elastic region and with finite element analysis results in elastic-plastic region.

An Improved Joint Model and Equations for Flexibility of Tubular Joints

1990 ◽  
Vol 112 (2) ◽  
pp. 157-168 ◽  
Author(s):  
Y. Ueda ◽  
S. M. H. Rashed ◽  
K. Nakacho
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Bending Moment ◽  
Joint Model ◽  
Initial Stiffness ◽  
Element Analysis ◽  
Joint Flexibility ◽  
Elastic Plastic ◽  
Tubular Joints ◽  
Different Types

In tubular frames with simple joints, joints may show considerable flexibility in the elastic as well as the elastic-plastic ranges. Such flexibility may have large effects on the behavior of the structure as a whole. In a previous paper, an effective simple model of tubular joints is developed. The model takes account of joint flexibility in the elastic as well as the elastic-plastic ranges based on elastic-fully plastic load-displacement relatioships. In this paper an improved joint model is presented to provide better accuracy while maintaining simplicity. The accuracy of the model is confirmed through comparisons with results of finite element analysis. Equations to evaluate the initial stiffness of tubular T and Y-joints when braces are subjected to axial compression or in-plane bending moment are also presented. Such equations for different types of joints in different loading conditions are needed in order to avoid expensive calculations to evaluate the initial stiffness of joints.

Finite Element Analysis of the Influence of Balance Mode on Rolling Mill Universal Spindle Strength

2014 ◽  
Vol 548-549 ◽  
pp. 449-453 ◽  
Author(s):  
Zhi Qiang Guo ◽  
Ze Lu Xu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Mechanical Model ◽  
Rolling Mill ◽  
Loading Condition ◽  
Equivalent Stress ◽  
Bending Moment ◽  
Element Model ◽  
Element Analysis ◽  
Universal Spindle

For the problem of balance bearing of universal spindle in rolling mill being prone to damage, the paper established mechanical model and finite element model of universal spindle. The paper has analyzed that the shear and bending moment in the middle of the shaft is the largest. The fillet near shoulder of balance bearing of the spindle is dangerous part. In order to reduce principal stress of universal spindle caused by moment, the paper improved balance mode of the spindle. The equilibrant was applied from in one place of shaft to put in two places. After optimizing, equivalent stress of the spindle is slight smaller than before under the same loading condition, which illustrates that the strength of the spindle is appropriately improved. Although the effect is not obvious, this has played a guiding role for the optimization of balance mode of universal spindle.

Comparison of Cyclic and Burst Test Result With FE Simulation of a Locally Thinned Pipe Bend

2011 ◽  
Author(s):  
Wolf Reinhardt ◽  
Ali Asadkarami
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Structural Integrity ◽  
Degradation Mechanism ◽  
Element Analysis ◽  
Pipe Bend ◽  
Elastic Plastic ◽  
Piping Systems ◽  
Cyclic Part ◽  
Test Result

Thinning of Carbon steel pipe subjected to water flow has been observed in many piping systems. The feeder pipes in CANDU® reactors have been found susceptible to this degradation mechanism. In response, an industry program has been initiated to investigate the effect of local thinning on structural integrity. A CANDU® feeder pipe bend specimen was thinned locally to about 70% of pressure based thickness near the weld at the onset of the bend. The test specimen was subjected to severe pressurized cyclic bending for over 1600 cycles, and was subsequently pressurized to failure under a constant applied bending deformation. The failed specimen was subjected to metallurgical examination. The present paper reports the results of a finite element analysis of the cyclic part of the test and an elastic plastic analysis for failure under pressurization. The results are compared with the experimental outcomes. The conclusions address specifically the test, more generally the failure of thinned pipe and the use of elastic-plastic finite element analysis to predict failure due to pressurization.

Use of NC3658 Flange Design Rules for B16.47 Flanges: An Analytical and Finite Element Based Study

2014 ◽  
Author(s):  
Anindya Bhattacharya ◽  
Michael P. Cross
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Bending Moment ◽  
Element Analysis ◽  
Allowable Limit ◽  
Applied Loading ◽  
Plate And Shell ◽  
Piping Systems ◽  
Bolt Stress ◽  
Pipe Size

The Design of flanges can be approached through different routes some of which [1] involve use of plate and shell theory and some [2] use concepts like “Equivalent Pressure”. A rigorous finite element analysis is a solution, but it is not always practical to do so considering the complexity of the problem and the man-hour requirement for the same. Particularly for piping systems where the number of flanges are many, an engineer always looks for a robust and easy to apply method and the method outlined in the American Boiler and Pressure Vessel Code ASME SEC III (for nuclear plants) [2], paragraph NC3658.3 provides one such method. It simply involves checking if the applied bending moment is within an allowable limit. Theoretically this method addresses the design from the standpoint of checking the bolt stress and also if the applied loading will overstress the flange. This method can easily be developed in simple spreadsheet form and is an integral part of almost every commercially available pipe stress program. The difficulty of using this method is that its applicability has been recommended in [2] as for ASME B16.5 flanges only i.e. for a maximum pipe size of 24″. Frequently an engineer encounters a pipe size which is greater than 24″ and the applicability of this method for such flanges becomes a question mark. In this paper, applicability of the NC3658.3 method for flanges >24″ has been investigated based on the standpoint of computing operating stress in bolts which is the basis of this method and also the results have been checked against finite element analysis.

A Study on Effect of Shape Irregularities on Collapse Loads of Pipe Bends with Critical Circumferential Throughwall Crack under In-Plane Closing Bending

2014 ◽  
Vol 592-594 ◽  
pp. 980-984
Author(s):  
Sumesh Sasidharan ◽  
Arunachalam R. Veerappan ◽  
Subramaniam Shanmugam
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Detrimental Effect ◽  
Bending Moment ◽  
Collapse Load ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Circumferential Crack ◽  
Plane Bending

The presence of thorough wall circumferential cracks has a detrimental effect on collapse load of elbows. The existing theoretical solutions do not correctly quantify the weakening effect due to the presence of the circumferential through wall crack in shape imperfect pipe bends. The present study has been done to investigate the effect of ovality and thinning on the collapse moment of 90° elbow with critical throughwall circumferential crack under in-plane bending moment using elastic-plastic finite element analysis considering large geometry change.

Sign in / Sign up

Export Citation Format

Share Document