Comparison on Stress Concentration Factors of Y/T Tubular Joints Between Numerical and Parametric Formulation Results

2005 ◽  
Author(s):  
Stefano Baratella ◽  
Dario Boote ◽  
Fabio Petrillo ◽  
Fabrizio Stefani
Keyword(s):  
Stress Concentration ◽  
Numerical Models ◽  
High Stress ◽  
Bending Moment ◽  
Steel Structures ◽  
Element Analysis ◽  
High Stress Concentration ◽  
Wide Range ◽  
Long Time ◽  
Stress Concentration Factors

The action of environmental loads such as wind and waves on offshore steel structures is locally emphasized by complex tubular connections, giving place to high stress concentration in correspondence of welds between pipe elements. This phenomenon, which heavily influences the fatigue life of the joint and, as a consequence, the operability of the whole platform, can be quantified by the Stress Concentration Factor. SCF can be determined either by experimental approach, numerical analysis and parametrical formulas developed mainly in the seventies-eighties by specialized authors like Kuang, Wordsworth, Smedley and Efthymiou. Even though these formulas, quoted as reference in the main world recognized rules, represented for a long time a useful tool for the designers of most projects, some discrepancies have been found to exist among them. A research has then been jointly promoted by University of Genoa and RINA Industry in order to compare the results of the parametric formulas with those coming from a finite element analysis performed on very refined numerical models made of brick elements. In this investigation attention has been focused on Y/T type joints; a wide range of configurations has been analysed by varying the most important parameters defining the geometry of the joint. Each configuration has been loaded by axial force and in/out of plane bending moment.

Development of Design Curve for Sweepolet Subjected to Acoustic Induced Vibration

2016 ◽  
Author(s):  
Yuqing Liu ◽  
Philip Diwakar ◽  
Dan Lin ◽  
Ismat Eljaouhari ◽  
Ajay Prakash
Keyword(s):  
Fatigue Life ◽  
Stress Concentration ◽  
Fatigue Failure ◽  
High Stress ◽  
Peak Stress ◽  
Acoustic Energy ◽  
Piping System ◽  
Element Analysis ◽  
Design Curve ◽  
High Stress Concentration

High acoustic energy has the potential to cause severe Acoustic Induced Vibration (AIV) that leads to fatigue failure at high stress concentration regions such as fittings in a piping system. Sweepolet fittings have been extensively used as mitigation to counteract the risk of fatigue failure caused by AIV. The advantages of a sweepolet are its integrally reinforced contoured body and low stress concentration. However, there are inconsistencies in published standards and regarding the design limits for sweepolet subjected to AIV. In this paper, Finite Element Analysis is conducted to simulate high frequency pipe shell wall vibration caused by acoustic energy inside the pipe. Peak stress and the associated minimum fatigue life are calculated for sweepolet and sockolet under the same acoustic excitation. By comparing the stress level to that of a sockolet whose design limit to AIV had been published, the design curve and fatigue life equation for sweepolet are developed.

Analysis and validation of femur bone data using finite element method under static load condition

2019 ◽  
Vol 233 (16) ◽  
pp. 5547-5555 ◽  
Author(s):  
S Mathukumar ◽  
VA Nagarajan ◽  
A Radhakrishnan
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Static Load ◽  
High Stress ◽  
Load Condition ◽  
Computational Method ◽  
Medical Attention ◽  
Element Analysis ◽  
High Stress Concentration ◽  
Femur Bone

Humans face bone fracture when they unfortunately met an accident, which requires timely medical attention for healing and repairing the fractured bone; otherwise that paralyzes their life. 3D modeling technique with computational method is very helpful at the side of doctors for healing and repairing the damaged bones. Fractional bone healing is one of the natural processes, which regain the mechanical reliability of the bone to a limited level of failures. The relationship between the biology and mechanics has introduced a new branch namely biomechanics. Various biomechanics models were used to identify the fracture for different patients and helps in the fracture treatment. The aim of this work is to find out the high stress concentration area of the femur bone, which has been extracted as image from computer tomography scanner. The retrieved noise-free femur bone image is tested by the static load condition with the help of the finite element analysis. The result obtained from the testing of different loads has been compared with the existing literature. It is found that the femur bone has tensile and compressive stress, and the neck area of the femur is at a very high stress concentration. The outcome of this work is much supportive to orthopedic surgeons in femur surgery and bone prosthesis by avoiding experiments on femur bone.

A FE Model to Predict the Stress Concentration Factors in the Tensile Armor Wires of Flexible Pipes Inside End Fittings

2013 ◽  
Author(s):  
José Renato M. de Sousa ◽  
George C. Campello ◽  
Fabiano Bertoni ◽  
Gilberto B. Ellwanger
Keyword(s):  
Stress Concentration ◽  
High Stress ◽  
Axial Stiffness ◽  
Fe Model ◽  
Acceptance Test ◽  
Stress Distributions ◽  
High Stress Concentration ◽  
Flexible Pipes ◽  
The Wire ◽  
Stress Concentration Factors

In this work, a bidimensional finite element (FE) approach is proposed to estimate the stresses induced in the tensile armor wires inside end fittings (EF) of flexible pipes. This approach accounts for the residual stresses caused by the mounting procedure and the deformed configuration of the wire. The resin and its interaction with the wires are also addressed. A parametric study was performed aiming at investigating the influence of three parameters on the stress state along the wire, i. e., the contact conditions between the resin and the wire inside the EF, the stress levels induced during the factory acceptance test (FAT) or the offshore leak test (OLT) and the resin elastic properties. The study pointed that high stress concentration is induced in the transition between the flexible pipe’s body and the EF and the stress distribution along the wire may be significantly affected by these parameters. Moreover, the apparent axial stiffness of the wire is also modified by its anchoring conditions, which may lead to non-uniform stress distributions among the wires of the tensile armor layers.

Residual Stress Estimation in Crossbores With Bauschinger Effect Inclusion Using FEM and Strain Energy Density

1999 ◽  
Vol 121 (4) ◽  
pp. 358-363 ◽  
Author(s):  
E. A. Badr ◽  
J. R. Sorem ◽  
S. M. Tipton
Keyword(s):  
Finite Element Analysis ◽  
Stress Concentration ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Analytical Approach ◽  
Bauschinger Effect ◽  
High Stress ◽  
Element Analysis ◽  
Elastic Plastic ◽  
High Stress Concentration

Crossbore intersections in liquid ends of positive displacement pumps (PDPs) have regions with high stress concentration. Due to the cyclic loading that occurs in most PDPs, these stress concentration points are susceptible to fatigue cracking. In order to prolong their life, the liquid ends are often overpressurized (autofrettaged), thus inducing beneficial compressive hoop stresses in these critical regions upon removal of the autofrettage pressure. This autofrettage process drives the region of high stress concentration beyond the elastic limit and well into the elastic-plastic region. Elastic-plastic stresses and strains due to loading and unloading were analyzed in crossbore geometries, with Bauschinger effect included, using 3-D finite element analysis of the liquid end. For comparison, an analytical approach was developed, based on the strain energy density criterion first proposed by Glinka. The approach was modified to include the Bauschinger effect for precise estimation of such stresses and strains. Good correlation was observed between elastic-plastic crossbore stresses and strains predicted by the analytical approach and the finite element analysis.

New Power Transmission Chain Design

1986 ◽  
Vol 108 (3) ◽  
pp. 255-261
Author(s):  
Y. Kin ◽  
R. Dubrovsky
Keyword(s):  
Stress Concentration ◽  
Power Transmission ◽  
High Stress ◽  
Variable Loading ◽  
Experimental Stress Analysis ◽  
High Stress Concentration ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
A Chain ◽  
Very High

Precision multiple roller power transmissions are investigated in this work. These chains transfer significant power and move with very high velocity. They are subjected to variable loading with strong vibration and impact components, and require forced stream lubrication. Because of these severe working conditions, chain life is limited by the fatigue, and the chain plates are the weakest elements in many cases. It is shown that fatigue life is significantly decreased by fretting action, high stress concentration in the plates, and the impossibility of maintaining a uniform force distribution across the multiple lines of a chain. The results of the performed experimental stress analysis under static and variable loading are given for the different plate geometries. The plates with a variety of stress reducers located in different areas are investigated, and theoretical and effective stress concentration factors are determined. Based on that, new plate chain designs are proposed. These new designs use fewer lines to transfer the same power as conventional chains.

Stress Concentration Factors in T and K-T Tubular Joints Using Finite Element Analysis

1988 ◽  
Vol 110 (4) ◽  
pp. 246-254 ◽  
Author(s):  
O. D. Dijkstra ◽  
R. S. Puthli ◽  
H. H. Snijder
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Axial Load ◽  
Bending Moment ◽  
The Finite Element Method ◽  
Element Analysis ◽  
Tubular Joints ◽  
Tubular Joint ◽  
Concentration Factors ◽  
Stress Concentration Factors

Stress concentration factors (SCFs) in a T and a K-T tubular joint have been determined using the finite element method (FEM). The SCFs are determined for basic load cases (axial load or bending moment) in one of the braces or in the chord. The results of the FEM are compared with available experimental data and with parametric formulas. The T-joint results for brace loadings agree reasonably with the parametric formulas. The K-T joint results for in-plane bending agree reasonably with the parametric formulas.

Mechanical Behavior of Notched SiC/SiC Composites

2001 ◽  
Author(s):  
Gregory N. Morscher ◽  
John Z. Gyekenyesi ◽  
Andrew L. Gyekenyesi
Keyword(s):  
Stress Concentration ◽  
Gas Turbines ◽  
High Stress ◽  
Thermoelastic Stress ◽  
Ceramic Matrix Composites ◽  
Matrix Cracking ◽  
Notch Sensitivity ◽  
Matrix Composites ◽  
High Stress Concentration ◽  
Wide Range

Gas turbine components such as combustor liners or turbine vanes are subject to regions of high stress-concentration, e.g. attachment to the frame or at cooling holes. Ceramic matrix composites (CMCs) are potential materials for high temperature applications in gas turbines. They offer some capability to relieve stress at regions of high stress-concentration via matrix damage accumulation. In this study notch sensitivity was examined for woven SiC fiber reinforced, melt-infiltrated SiC matrix composites with a BN interphase, utilizing either Hi-Nicalon™ fibers or the stiffer Sylramic® fibers. The double-edge notched tensile test approach was used for a wide range of notch sizes and specimen widths. Both composite systems exhibited mild notch sensitivity similar to other CMC systems. Acoustic emission, detected during the tensile tests, indicated that matrix cracking occurred around notches at net-section stresses below the stress where matrix cracking first occurs in unnotched specimens. However, thermoelastic stress analysis did not show any measurable stress relief around notches after the specimens were preloaded.

Fatigue Failure Analysis Using the Theory of Critical Distance

2011 ◽  
Vol 462-463 ◽  
pp. 663-667 ◽  
Author(s):  
Ruslizam Daud ◽  
Ahmad Kamal Ariffin ◽  
Shahrum Abdullah ◽  
Al Emran Ismail
Keyword(s):  
Stress Concentration ◽  
Fatigue Failure ◽  
Notch Root ◽  
High Stress ◽  
Critical Distance ◽  
Future Research ◽  
Element Analysis ◽  
Linear Elastic ◽  
The Finite Element Analysis ◽  
Elastic Fracture

This paper explores the initial potential of theory of critical distance (TCD) which offers essential fatigue failure prediction in engineering components. The intention is to find the most appropriate TCD approach for a case of multiple stress concentration features in future research. The TCD is based on critical distance from notch root and represents the extension of linear elastic fracture mechanics (LEFM) principles. The approach is allowing possibilities for fatigue limit prediction based on localized stress concentration, which are characterized by high stress gradients. Using the finite element analysis (FEA) results and some data from literature, TCD applications is illustrated by a case study on engineering components in different geometrical notch radius. Further applications of TCD to various kinds of engineering problems are discussed.

An Estimation Formula of the Stress Concentration Factor of the Butt-Welded Joint

2007 ◽  
Vol 353-358 ◽  
pp. 1995-1998
Author(s):  
Byeong Choon Goo
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Gas Metal Arc Welding ◽  
Element Analysis ◽  
Butt Weld ◽  
Estimation Formula ◽  
Metal Arc Welding ◽  
Concentration Factors ◽  
Stress Concentration Factors

The purpose of this paper is to develop an estimation formula of stress concentration factors of butt-welded components under tensile loading. To investigate the influence of weld bead profiles on stress concentration factors of double V groove butt-welded joints, butt-welded specimens were made by CO2 gas metal arc welding. And the three main parameters, the toe radius, flank angle and bead height were measured by a profile measuring equipment. By using the measured data, the influence of three parameters on the stress concentration factors was investigated by a finite element analysis. It is shown that the three parameters have similar effects on the stress concentration factors. According to the simulation results, a formula to estimate the stress concentration factors of butt-weld welded structures was proposed and the estimated concentration factors from the formula were compared with the results obtained by the finite element analysis. The two results are in a good agreement.

Notch (stress concentration) factor estimation of a cylinder under internal pressure using different approaches

2021 ◽  
Vol 63 (5) ◽  
pp. 430-435
Author(s):  
Osman Atalay ◽  
Ihsan Toktas
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Stress Concentration ◽  
Mechanical Design ◽  
Computer Software ◽  
Element Analysis ◽  
Notch Stress ◽  
Artificial Neural ◽  
Effect Parameter ◽  
Stress Concentration Factors

Abstract Today, fluid transportation via pipes can be found in many sectors. Therefore, safe fluid transportation possesses critical importance. While working, transportation pipes are exposed to unwanted loads that culminate in stresses which cause deformation on the part geometry especially in sharp corners, holes or sudden cross-section change areas considered as notched. The notch effect parameter is considered in the mechanical design formulas. This study is interested in the notch factor that is estimated for a cylinder which undergoes an inner pressure. Some users can use false numerical values due to misreading or lack of attention. Because of this reason, graphs were converted to the numerical value by using computer software. In this study, Peterson’s chart was accepted as scientifically valid. Stress concentration factors were obtained by using four other approaches. These are regression, analytical, artificial neural network and finite element analysis. Among these models, high accuracy values were given by the artificial neural network model.

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