Finite Element Analysis Based Stress Intensification Factor Calculation and Comparison With Various Approaches for Stress Intensification Factor Calculation

2017 ◽  
Author(s):  
Mahesh Kulkarni ◽  
Vivek Dewangan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Branch Pipe ◽  
Bending Moment ◽  
Piping System ◽  
Element Analysis ◽  
Process Industries ◽  
Average Value ◽  
Stress Intensification Factor ◽  
Plane Bending

Piping caters a major role in the process industries wherein stress intensification factor (SIF) express the Piping flexibility of the system. A typical Piping system consists of combination of pipes and various fittings with intersection geometries namely bend, tee, reducer, etc. A SIF is a multiplier on nominal bending stress so that the effect of geometry and welding can be considered in a flexibility analysis. An attempt has been made to compare the SIF values among ASME Piping B31.3, Welded Research Council (WRC) Bulletin 329, Paulin Research Group (PRG) empirical data and shell-based finite element analysis (FEA) for various tee sections based on in-plane and out-plane bending moments through this paper. The bending moment which causes tee to open/close in the plane formed by two limbs of tee is called in-plane bending moment. The bending moment which causes branch of tee to displace out of the plane retaining run pipe steady is called Out-plane bending moment. ASME B31.3 provide guidelines to evaluate SIF values through empirical formulation as per Appendix-D with few limitations listed below. 1. Valid for d/D < 0.5 only 2. Non-conservative for 0.5 < d/D < 1.0 3. Valid for D/T ≤ 100 4. SIF values calculated with respect to header pipe. There is no difference in SIF values for header and branch pipe and it is the average value. WRC 329 was published in 1987 and has not been updated taking ASME B31.3 latest edition into account. PRG carried out SIF for the various sizes and types of tee fittings and prepared correlation equations through detailed FEA using nonlinear regression and test data.

Analytical Determination of Stress Indices and Stress Intensification Factor for an Extruded Nozzle of Super Pipe

2018 ◽  
Author(s):  
Lv Feng ◽  
Zhou Gengyu ◽  
Qian Haiyang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Branch Pipe ◽  
Bending Moment ◽  
Analytical Determination ◽  
Element Analysis ◽  
Stress Indices ◽  
Asme Code ◽  
Stress Intensification Factor ◽  
Plane Bending

The super pipe nozzles in nuclear power plants are usually designed to be in compliance with the requirements of Class 2 piping of Section III of the ASME Boiler and Pressure Vessel Code. The stress indices B2 and stress intensification factor i are required for the stress evaluation. In the past two decades, the hot extrusion forming technology has been widely used to manufacture those nozzles, instead of traditional insert weldolets. However, previous extruded nozzle stress analyses have shown B2 that the calculated stresses may exceed the limits in some working conditions. The objective of present study is to determine the stress indices and stress intensification factor for an extruded nozzle of the supper pipe by the finite element method and to evaluate the conservatism of those factors from the ASME Code formulae. In this paper, a three-dimensional finite element model of an extruded nozzle is developed. Four load cases are considered, which are corresponding to an in-plane bending moment and an out-plane bending moment applied at the run pipe side and at the branch pipe side, respectively. The magnitude of bending moment is assumed to be 1000Nm. The stress indices B2r, B2b, C2r, C2b, K2r and K2b, where the subscript r and b refer to the run pipe and B2r the branch pipe, are calculated based on the finite element analysis results. The stress intensification factor ir and ib are determined by the empirical formula: ir = C2r*K2r/2 and ib = C2b*K2b/2. Further, the developed factors are compared with those calculated from the ASME code formulae. It is found that the stress indices B2r and B2b obtained from the linear elastic finite element analysis are conservative. Currently, the values of B2r and B2b gained from the ASME code formulae are more appropriate for the stress evolution. The stress intensification factors ir and ib obtained from the analytical determination are lower than those calculated from the ASME code formula. For the extrude nozzle studied, the factor ir decreases 30% and the factor ib decreases about 3.3%.

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.

Nonlinear Analysis of Pressurized Piping Elbows Subjected to Out-of-Plane Bending

2006 ◽  
Vol 306-308 ◽  
pp. 351-356 ◽  
Author(s):  
Asnawi Lubis ◽  
Jamiatul Akmal
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Cross Section ◽  
Bending Moment ◽  
Pressure Reduction ◽  
Element Analysis ◽  
Out Of Plane ◽  
Plane Bending ◽  
Reduction Effect

The behavior of piping elbows under bending and internal pressure is more complicated than expected. The main problem is that the coupling of bending and internal pressure is nonlinear; the resulting stress and displacement cannot be added according to the principle of superposition. In addition, internal pressure tends to act against the effect caused by the bending moment. If bending moment ovalise the elbow cross-section, with internal pressure acting against this deformation, then the ovalised cross section deform back to the original circular shape. It is then introduced the term “pressure reduction effect”, or in some literature, “pressure stiffening effect”. Current design piping code treats the pressure reduction effect equally for in-plane (closing and opening) moment and outof- plane moment. The aim of this paper is to present results of a detailed finite element analysis on the non-linear behavior of piping elbows of various geometric configurations subject to out-of-plane bending and internal pressure. Specifically the standard Rodabaugh & George nonlinear pressure reduction equations for in-plane closing moment are checked in a systematic study for out-of-plane moment against nonlinear finite element analysis. The results show that the pressure stiffening effects are markedly different for in-plane and out-of-plane bending.

scholarly journals Effect of Ovality in Inlet Pigtail Pipe Bends Under Combined Internal Pressure and In-Plane Bending for Ni-Fe-Cr B407 Material

2017 ◽  
Vol 62 (3) ◽  
pp. 1881-1887
Author(s):  
P. Ramaswami ◽  
P. Senthil Velmurugan ◽  
R. Rajasekar
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Limit Load ◽  
Outer Radius ◽  
Factor H ◽  
Geometrical Shape ◽  
Element Analysis ◽  
Pipe Bend ◽  
Plane Bending

Abstract The present paper makes an attempt to depict the effect of ovality in the inlet pigtail pipe bend of a reformer under combined internal pressure and in-plane bending. Finite element analysis (FEA) and experiments have been used. An incoloy Ni-Fe-Cr B407 alloy material was considered for study and assumed to be elastic-perfectly plastic in behavior. The design of pipe bend is based on ASME B31.3 standard and during manufacturing process, it is challenging to avoid thickening on the inner radius and thinning on the outer radius of pipe bend. This geometrical shape imperfection is known as ovality and its effect needs investigation which is considered for the study. The finite element analysis (ANSYS-workbench) results showed that ovality affects the load carrying capacity of the pipe bend and it was varying with bend factor (h). By data fitting of finite element results, an empirical formula for the limit load of inlet pigtail pipe bend with ovality has been proposed, which is validated by experiments.

scholarly journals A Review on Numerical Analysis of RC Flat Slabs Exposed to Fire

2020 ◽  
Vol 27 (1) ◽  
pp. 1-5
Author(s):  
Hanadi Naji ◽  
Nibras Khalid ◽  
Mutaz Medhlom
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Numerical Analysis ◽  
Bending Moment ◽  
Mechanical And Thermal Properties ◽  
Vertical Deflection ◽  
Element Analysis ◽  
Flat Slabs ◽  
Numerical Studies ◽  
The Finite Element Analysis

This paper aims at presenting and discussing the numerical studies performed to estimate the mechanical and thermal behavior of RC flat slabs at elevated temperature and fire. The numerical analysis is carried out using finite element programs by developing models to simulate the performance of the buildings subjected to fire. The mechanical and thermal properties of the materials obtained from the experimental work are involved in the modeling that the outcomes will be more realistic. Many parameters related to fire resistance of the flat slabs have been studied and the finite element analysis results reveal that the width and thickness of the slab, the temperature gradient, the fire direction, the exposure duration and the thermal restraint are important factors that influence the vertical deflection, bending moment and force membrane of the flat slabs exposed to fire. However, the validation of the models is verified by comparing their results to the available experimental date. The finite element modeling contributes in saving cost and time consumed by experiments.

Creep Life Simulation and Assessment of High Temperature Piping Systems and Components

2012 ◽  
Author(s):  
Brian Rose ◽  
James Widrig
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
High Temperature ◽  
Creep Behavior ◽  
Material Behavior ◽  
Piping System ◽  
Remaining Life ◽  
Creep Life ◽  
Element Analysis ◽  
Piping Systems

High temperature piping systems and associated components, elbows and bellows in particular, are vulnerable to damage from creep. The creep behavior of the system is simulated using finite element analysis (FEA). Material behavior and damage is characterized using the MPC Omega law, which captures creep embrittlement. Elbow elements provide rapid yet accurate modeling of pinching of piping, which consumes a major portion of the creep life. The simulation is used to estimate the remaining life of the piping system, evaluate the adequacy of existing bellows and spring can supports and explore remediation options.

Dynamic Interaction of High-Voltage Power Transformer Bushings, Turrets, and Tanks

2018 ◽  
Vol 34 (1) ◽  
pp. 397-421 ◽  
Author(s):  
Guo-Liang Ma ◽  
Qiang Xie ◽  
Andrew Whittaker
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
High Voltage ◽  
Power Transformer ◽  
Bending Moment ◽  
Dynamic Interaction ◽  
Electrical Performance ◽  
Element Analysis ◽  
Ground Shaking ◽  
Input Motion

High-voltage (HV) bushings are attached to a power transformer tank either directly or indirectly via turrets. Turrets are used to achieve electrical performance requirements, but their potential impact on the seismic performance of the supported bushings has not been considered. Earthquake simulator testing and finite-element analysis were used to quantify the amplification of ground shaking through tanks (220- and 500-kV) and turrets to the points of attachment of roof- and sidewall-supported bushings. Substantial amplification of motion was seen in both physical experiments and numerical simulations. Sample bracing schemes external to the transformer tank were investigated to potentially reduce the motions experienced by the bushings. Bushing tip displacements were reduced in all stiffening cases studied, but the outcomes for bending moment at the bushing-turret connection were mixed, with no change in some cases and significant reductions in others. The physical and numerical studies described in this paper make clear the importance of dynamic interaction of bushings, turrets, and the power transformer tank. The methods currently used to address the amplification of input motion from the base of a tank to the points of attachment of its bushing are inadequate. The seismic design of HV power transformer tanks and turrets should be supported by finite-element analysis of validated models to avoid dynamic interaction in the bushing-turret-tank system, to minimize seismic demand on the transformer bushings, and to minimize the risk of substation damage in earthquakes.

Capacity Analysis of PE Pipeline With Non-Planar Defect

2013 ◽  
Author(s):  
Weijie Jiang ◽  
Jianping Zhao ◽  
Dingyue Chen
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Constitutive Model ◽  
Mechanical Performance ◽  
Orthogonal Design ◽  
Bending Moment ◽  
Limit Load ◽  
Capacity Analysis ◽  
Element Analysis ◽  
Load Factors

A tensile test of buried PE pipe is designed to test the mechanical performance. Then the constitutive model for the PE pipe can be established. The limit load of the PE pipe with local thinning defect can be studied with the method of combining the orthogonal design of experiment and finite element analysis. Then the factors of local thinning defect pipe limit load factors can be analyzed. The results show that the depth of the defect has a great effect on the limit load (internal pressure and bending moment) of PE pipe. The effects that the axial length of the defect and the circumferential length of the defect have on the limit load are not significant.

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