Reduction of Stress Concentration in Bolt-Nut Connectors

2005 ◽  
Vol 128 (6) ◽  
pp. 1337-1342 ◽  
Author(s):  
Sriman Venkatesan ◽  
Gary L. Kinzel
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Stress Distribution ◽  
Stress Concentration Factor ◽  
Load Distribution ◽  
Element Model ◽  
Structural Systems ◽  
Stress Concentrations ◽  
Safety And Reliability ◽  
Geometric Designs

Bolt-nut connectors play an important role in the safety and reliability of structural systems. Stress concentration due to unequal load distribution can cause fatigue failure in bolt-nut connectors. In this paper, the stress distribution in bolt-nut connectors is studied using an axisymmetric finite element model. Various geometric designs proposed in the literature were studied to determine the extent to which they reduce stress concentrations. Some well known modifications do significantly reduce the stress concentration factor (up to 85%) while other changes produce much more modest changes. The design modifications include things such as grooves and steps on the bolt and nut, and reducing the shank diameter of the bolt. All of the changes also result in a reduction in weight.

Mechanical Properties on the Welded Connection of Pipe and Hollow Spheres Joints

2011 ◽  
Vol 189-193 ◽  
pp. 3452-3457
Author(s):  
Ya Jie Yan ◽  
Hong Gang Lei ◽  
Xue Yang
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Stress Distribution ◽  
Wall Thickness ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Hollow Spheres ◽  
Steel Structures ◽  
Element Analysis ◽  
Static Tests

Taking pipe - hollow spherical node as the object, and using ANSYS finite element analysis software, established five kinds of finite element model to analyze the stress concentration at the weld connection of the different connections of steel structures - hollow ball under the uniaxial tension. Obtained this node’s stress concentration factor, stress distribution, by changing the hollow spherical diameter and wall thickness, pipe’s diameter and wall thickness, obtained the trend of the stress concentration factor under different control ball matches. Take static tests on typical structures of two specifications 6 hollow sphere nodes, get the measured stress concentration factor, and stress distribution of this node. Through comparative analysis of theoretical analysis and experimental results, show that the two rules are consistent. The research results can provide basis for improving the pipe - hollow spherical joints connecting structural.

scholarly journals Stress Concentration Factor of A Two-Planar Double KT Tubular Joint due to In-Plane Bending Loading in Steel Offshore Structures

2018 ◽  
Vol 177 ◽  
pp. 01006
Author(s):  
Prastianto Rudi Walujo ◽  
Hadiwidodo Yoyok Setyo ◽  
Fuadi Ibnu Fasyin
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Element Model ◽  
Offshore Structures ◽  
Geometrical Parameters ◽  
Offshore Structure ◽  
Wide Range ◽  
Tubular Joint

The purpose of this study is to investigate the proper Stress Concentration Factor (SCF) of a 60° two-planar DKT tubular joint of a tripod wellhead offshore structure. So far, calculation of SCF for a multi-plane tubular joint was based on the formulation for the simple/uniplanar tubular joints that yield in over/under prediction of the SCF of the joint. This situation in turn decreasing the accuracy of fatigue life prediction of the structures. The SCF is one of the most important parameters in the tubular joint fatigue analysis. The tubular joint is modelled as finite element models with bending loads acting on the braces that cover a wide range of dimensionless geometrical parameters (β, τ, γ). The effect of such parameters on the SCF distribution along the weld toe of braces and chord on the joint are investigated. Validation of the finite element model has shown good agreement to the global structural analysis results. The results of parametric studies show that the peak SCF mostly occurs at around crown 2 point of the outer central brace. The increase of the β leads to decrease the SCF. While the increase of the τ and γ leads to increase the SCF. The effect of parameter β and γ on the SCF are greater than the effect of parameter τ.

scholarly journals The Effect of Framework Design on Stress Distribution in Implant-Supported FPDs: A 3-D FEM Study

2010 ◽  
Vol 04 (04) ◽  
pp. 374-382 ◽  
Author(s):  
Oguz Eraslan ◽  
Ozgur Inan ◽  
Asli Secilmis
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Stress Distribution ◽  
Bone Structure ◽  
Von Mises Stress ◽  
Stress Concentrations ◽  
Biomechanical Behavior ◽  
Framework Design ◽  
Occlusal Surfaces ◽  
Von Mises

Objectives: The biomechanical behavior of the superstructure plays an important role in the functional longevity of dental implants. However, information about the influence of framework design on stresses transmitted to the implants and supporting tissues is limited. The purpose of this study was to evaluate the effects of framework designs on stress distribution at the supporting bone and supporting implants.Methods: In this study, the three-dimensional (3D) finite element stress analysis method was used. Three types of 3D mathematical models simulating three different framework designs for implant- supported 3-unit posterior fixed partial dentures were prepared with supporting structures. Convex (1), concave (2), and conventional (3) pontic framework designs were simulated. A 300-N static vertical occlusal load was applied on the node at the center of occlusal surface of the pontic to calculate the stress distributions. As a second condition, frameworks were directly loaded to evaluate the effect of the framework design clearly. The Solidworks/Cosmosworks structural analysis programs were used for finite element modeling/analysis.Results: The analysis of the von Mises stress values revealed that maximum stress concentrations were located at the loading areas for all models. The pontic side marginal edges of restorations and the necks of implants were other stress concentration regions. There was no clear difference among models when the restorations were loaded at occlusal surfaces. When the veneering porcelain was removed, and load was applied directly to the framework, there was a clear increase in stress concentration with a concave design on supporting implants and bone structure.Conclusions: The present study showed that the use of a concave design in the pontic frameworks of fixed partial dentures increases the von Mises stress levels on implant abutments and supporting bone structure. However, the veneering porcelain element reduces the effect of the framework and compensates for design weaknesses. (Eur J Dent 2010;4:374-382)

Numerical stress analysis for fatigue evaluation of welded tubular T-joints

1993 ◽  
Vol 20 (2) ◽  
pp. 269-286 ◽  
Author(s):  
D. I. Nwosu ◽  
A. S. J. Swamidas ◽  
K. Munaswamy
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Stress Distribution ◽  
Stress Concentration Factor ◽  
Bending Stress ◽  
Element Analysis ◽  
T Joints ◽  
Shell Finite Element ◽  
Good Agreement

The stress distribution along the intersection of offshore tubular T-joints under the action of axial and in-plane and out-of-plane (bending) brace loading has been investigated using degenerated shell elements. The ratios of through-thickness membrane to bending stress and bending to total stress have been obtained using a simple linear interpolation between the stresses on the inner and outer surfaces of the tube. The nominal brace stress and the maximum principal stress values have been used for stress concentration factor determination. The influence of thickness and other geometric parameters on the stress distribution along the intersection was investigated in two ways, viz., increasing the chord thickness while maintaining a constant brace thickness, and keeping the chord thickness constant while reducing the brace thickness.Comparison of the shell finite-element results obtained in this study with the semiloof thin-shell finite-element results of the University College, London (UCL), exhibits good agreement. Good agreement exists between the results of this study and the UCL parametric equations for the chord and the brace of the joint, with a maximum difference of about 7% on the braceside around the saddle position. Comparisons between the finite-element results and other known parametric equations for stress concentration factor with different diametral, wall thickness, and chord thickness and ratios also show good agreement. A comparison of the results obtained from the finite-element analysis and the experimental results of the Canadian Cooperative Fatigue Studies Program, carried out at Memorial University of Newfoundland and University of Waterloo, is also made. Key words: stress distribution, finite-element analysis, stress concentration factors, membrane stress, bending stress, tubular T-joints.

scholarly journals Influence of Preparation Design, Restorative Material and Load Direction on The Stress Distribution of Ceramic Veneer in Upper Central Incisor

2021 ◽  
Vol 24 (3) ◽  
Author(s):  
Laura Célia Fernandes Meirelles ◽  
Fernanda Zapater Pierre ◽  
João Paulo Mendes Tribst ◽  
Clovis Pagani ◽  
Eduardo Bresciani ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Stress Distribution ◽  
Lithium Disilicate ◽  
Occlusal Plane ◽  
Central Incisor ◽  
Stress Concentrations ◽  
Element Analysis ◽  
Preparation Design

Objective: Evaluate the effect of four preparation designs, two ceramic materials, and two occlusion contact types on the stress distribution of ceramic veneer in upper central incisor. Material and methods:  3D-models were performed in the modeling software containing enamel, dentin, pulp, periodontal ligament and a base of polyurethane resin. The designs were modeled and exported to the computer aided engineering software to perform the static structural analysis. For the mesh, a total of 155429 tetrahedron elements and 271683 nodes were used, after a 10% convergence test. Two materials, lithium disilicate and feldspathic ceramics, were simulated. A static load of 100 N on 45º was applied on the incisal and middle thirds of the palatal tooth region, guided by the occlusal plane. The base was constrained in all directions. The Maximum Principal Stress was the failure criteria chosen for the analysis. Results: The Finite Element Analysis showed that the most conservative designs presented less stress concentration on the ceramic veneer. However, the highest tensile stress concentrations were observed on lithium disilicate veneer with extend design, on the middle third. The type of occlusal contact presented different stress patterns among the preparation designs; the incisal contact showed higher stress concentration compared to middle third contact regardless the ceramic material. Conclusions: To perform a ceramic veneer in upper central incisor, the feldspathic ceramic presented promising results and should be recommended when the extended design was done. Regarding contact types, the incisal contact is more prone to failure regardless the ceramic and preparation design.   Keywords Ceramics; Dental veneers; Finite element analysis.

A Novel Technique for Viewing Stress Distribution with Mechanoluminescence Materials

2008 ◽  
Vol 368-372 ◽  
pp. 1401-1404 ◽  
Author(s):  
Chen Shu Li ◽  
Chao Nan Xu ◽  
Hiroshi Yamada ◽  
Yusuke Imai ◽  
Hong Wu Zhang ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Calculation ◽  
Stress Concentration ◽  
Stress Distribution ◽  
Metal Substrate ◽  
Visualization Technique ◽  
Stress Concentrations ◽  
Novel Technique ◽  
Test Objects

We have successfully demonstrated that the stress distribution of a metal substrate can be directly displayed by coating SrAl2O4:Eu (SAO), a representative of strong mechanoluminescent materials, on the surface of test objects. An aluminum plate with SAO sensing film had been applied to experimental analysis of stress concentrations, and a numerical calculation via a finite element method confirmed that the observed real time mechanoluminescence images displayed the stress distribution. As a result, visualization of stress distribution on metal surface has been realized by ML images using SAO sensing film, and this novel visualization technique can be applied for viewing the stress concentration in various fields such as modeling, manufacturing and demonstration of an industrial product.

Stress Concentration in a Connectorized Optical Fiber

2000 ◽  
Author(s):  
John F. Malluck ◽  
Wilton W. King
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Stress Distribution ◽  
Optical Fiber ◽  
Surface Damage ◽  
Structural Mechanics ◽  
Stress Concentrations ◽  
Conical Cavity ◽  
Fillet Transition ◽  
Stress States

Abstract For the most part, analyses of fiber fractures in connectors have been in the form of postmortem fractography. Typically in these works, characteristics of prefracture stress states have been inferred from fracture surfaces, and plausible qualitative explanations have been advanced about the likely structural mechanics and circumstances leading to fractures. The authors and their colleagues have undertaken a number of investigations of relevant structural mechanics. These have served the useful purpose of elucidating gross mechanisms, but the influence of the fine details of stress distributions have been missing. Considered here is a cylindrical-ferrule connector for which, typically, the ferrule is ceramic with an outside diameter of 2.5mm or 1.25mm. The fiber to be terminated is bonded into a small-bore axial hole (capillary) in the ferrule by an epoxy or similar adhesive. In addition, fiber insertion into the capillary is facilitated by ferrule designs that provide a conical entrance cavity leading to the capillary. A very high percentage of fiber failures, both in the laboratory and the field, occur at the transition region between the fiber and the capillary; so analysis is focused on that region. The stress distribution within an optical fiber adhesively bonded to a ceramic ferrule is determined by the finite element method for uniform remote tension acting on the fiber. An axisymmetric model is constructed to represent the fiber, epoxy, and geometry of the ferrule under this particular loading condition. The resulting stress distribution is determined within the fiber and the epoxy layer using the ANSYS finite element code. Analysis of the stress distribution reveals the presence of two stress concentrations located at the surface of the fiber as the fiber enters the ferrule. One stress concentration occurs as the fiber encounters the epoxy within the conical cavity. The second stress concentration occurs as the fiber enters the capillary. These stress concentrations when combined with surface damage (flaws) may lead to fiber breakage. Further analysis reveals that a smooth fillet transition between entrance and capillary could significantly reduce the stress concentration at the capillary entrance. Finally, a simulation of epoxy debonding within the entrance cone reveals an increase of stress concentration at the capillary entrance.

Reduction of Free-Edge Stress Concentration

1985 ◽  
Vol 52 (4) ◽  
pp. 801-805 ◽  
Author(s):  
P. R. Heyliger ◽  
J. N. Reddy
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Finite Element Model ◽  
Three Dimensional ◽  
Element Model ◽  
Free Edge ◽  
Shear Stresses ◽  
Normal Stresses ◽  
Interlaminar Shear ◽  
Three Dimensional Elasticity

A quasi-three dimensional elasticity formulation and associated finite element model for the stress analysis of symmetric laminates with free-edge cap reinforcement are described. Numerical results are presented to show the effect of the reinforcement on the reduction of free-edge stresses. It is observed that the interlaminar normal stresses are reduced considerably more than the interlaminar shear stresses due to the free-edge reinforcement.

Research of the Connecting Form about the Spherical Shell and the Nozzle

2011 ◽  
Vol 413 ◽  
pp. 520-523
Author(s):  
Cai Xia Luo
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Finite Element Model ◽  
Spherical Shell ◽  
Maximum Stress ◽  
Peak Stress ◽  
Element Model ◽  
Small Opening ◽  
Large Opening ◽  
Reducing Stress

The Stress Distribution in the Connection of the Spherical Shell and the Opening Nozzle Is Very Complex. Sharp-Angled Transition and Round Transition Are Used Respectively in the Connection in the Light of the Spherical Shell with the Small Opening and the Large One. the Influence of the Two Connecting Forms on Stress Distribution Is Analyzed by Establishing Finite Element Model and Solving it. the Result Shows there Is Obvious Stress Concentration in the Connection. Round Transition Can Reduce the Maximum Stress in Comparison with Sharp-Angled Transition in both Cases of the Small Opening and the Large Opening, Mainly Reducing the Bending Stress and the Peak Stress, but Not the Membrane Stress. the Effect of Round Transition on Reducing Stress Was Not Significant. so Sharp-Angled Transition Should Be Adopted in the Connection when a Finite Element Model Is Built for Simplification in the Future.

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