Contact Stresses in Dovetail Attachments: Alleviation via Precision Crowning

2003 ◽  
Vol 125 (4) ◽  
pp. 1033-1041 ◽  
Author(s):  
G. B. Sinclair ◽  
N. G. Cormier
Keyword(s):  
Finite Element ◽  
Contact Stresses ◽  
Physical Models ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Large Fluctuations ◽  
Dimensional Finite Element ◽  
Hoop Stresses ◽  
Good Agreement ◽  
Made In

Previous studies of contact stresses in dovetail attachments provide verified finite element stresses as well as some simple physical models of such stresses. Generally there is good agreement between the finite element analysis and the simple physical models. Together the two identify a pinching mechanism as leading to large fluctuations in hoop stresses at the edges of contact. These fluctuating hoop stresses can be expected to be a major contributor to the fatigue of dovetail attachments. The present study investigates a method of alleviating the fluctuating hoop stresses. This method entails crowning of the contacting flat on a blade. Such crowning is in two orthogonal directions on the blade flat. Two-dimensional finite element analyses are made in both directions. These analyses indicate that significant reductions in fluctuating hoop stresses can be achieved by the method, provided the crowning is controlled sufficiently precisely.

Contact Stresses in Dovetail Attachments: Alleviation via Precision Crowning

2001 ◽  
Author(s):  
G. B. Sinclair ◽  
N. G. Cormier
Keyword(s):  
Finite Element ◽  
Contact Stresses ◽  
Physical Models ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Large Fluctuations ◽  
Dimensional Finite Element ◽  
Hoop Stresses ◽  
Good Agreement ◽  
Made In

Previous studies of contact stresses in dovetail attachments provide verified finite element stresses as well as some simple physical models of such stresses. Generally there is good agreement between the finite element analysis and the simple physical models. Together the two identify a pinching mechanism as leading to large fluctuations in hoop stresses at the edges of contact. These fluctuating hoop stresses can be expected to be a major contributor to the fatigue of dovetail attachments. The present study investigates a method of alleviating the fluctuating hoop stresses. This method entails crowning of the contacting flat on a blade. Such crowning is in two orthogonal directions on the blade flat. Two-dimensional finite element analyses are made in both directions. These analyses indicate that significant reductions in fluctuating hoop stresses can be achieved by the method, provided the crowning is controlled sufficiently precisely.

Contact Stresses in Dovetail Attachments: Physical Modeling

2002 ◽  
Vol 124 (2) ◽  
pp. 325-331 ◽  
Author(s):  
G. B. Sinclair ◽  
N. G. Cormier
Keyword(s):  
Finite Element ◽  
Physical Modeling ◽  
Physical Models ◽  
Shear Stresses ◽  
Major Contributor ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Large Fluctuations ◽  
Hoop Stresses ◽  
Good Agreement

Simple physical models for the stresses in dovetail attachments are developed. These models address: to slip or not to slip, nominal stresses during loading up, peak contact and shear stresses during loading up, hoop stresses during loading up, peak contact and shear stresses during unloading, and hoop stresses during unloading. Comparisons are made with a previous paper on companion finite element modeling. Generally there is good agreement between the simple physical models and the finite element analysis. Together the two identify a pinching mechanism as leading to large fluctuations in hoop stresses at the edges of contact. These fluctuating hoop stresses can be expected to be a major contributor to the fatigue of dovetail attachments.

Contact Stresses in Dovetail Attachments: Physical Modeling

2000 ◽  
Author(s):  
G. B. Sinclair ◽  
N. G. Cormier
Keyword(s):  
Finite Element ◽  
Physical Modeling ◽  
Physical Models ◽  
Shear Stresses ◽  
Major Contributor ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Large Fluctuations ◽  
Hoop Stresses ◽  
Good Agreement

Simple physical models for the stresses in dovetail attachments are developed. These models address: to slip or not to slip, nominal stresses during loading up, peak contact and shear stresses during loading up, hoop stresses during loading up, peak contact and shear stresses during unloading, and hoop stresses during unloading. Comparisons are made with a previous paper on companion finite element modeling. Generally there is good agreement between the simple physical models and the finite element analysis. Together the two identify a pinching mechanism as leading to large fluctuations in hoop stresses at the edges of contact. These fluctuating hoop stresses can be expected to be a major contributor to the fatigue of dovetail attachments.

Improved Three-Dimensional Crowning Profiles for Dovetail Attachments

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
J. R. Beisheim ◽  
G. B. Sinclair
Keyword(s):  
Finite Element Analysis ◽  
Gas Turbines ◽  
Three Dimensional ◽  
Contact Stresses ◽  
Element Analysis ◽  
Large Fluctuations ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Hoop Stresses ◽  
Fatigue Failures

Dovetail attachments in gas turbines are subject to fatigue failures. These fatigue failures occur as a result of large fluctuations in hoop stresses near the edges of contact in attachments. The high hoop stresses available for fluctuating are, in turn, the result of high contact stress peaks near the edges of contact. One means of alleviating these stresses is via crowning. Such crowned configurations are inherently three-dimensional and consequently present some challenges to obtaining convergent contact stresses with finite elements. Such challenges are met in the work of Beisheim and Sinclair (2008, “Three-Dimensional Finite Element Analysis of Dovetail Attachments With and Without Crowning,” ASME J. Turbomach., 130, pp. 021012-1–021021-8), and crowning is shown to reduce contact stresses by about 40%. The crowning profile used in that paper is the natural Hertzian profile of a segment of an ellipsoid. This note investigates an alternative profile with a view to increasing the area of contact, and thereby further reducing contact stresses. Converged contact stresses are obtained for both profiles, and demonstrate that the alternative profile can indeed reduce contact stresses by an additional 10%.

Finite Element Analysis of Nonuniformity of Tires with Imperfections5

2007 ◽  
Vol 35 (3) ◽  
pp. 226-238 ◽  
Author(s):  
K. M. Jeong ◽  
K. W. Kim ◽  
H. G. Beom ◽  
J. U. Park
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Element Model ◽  
Radial Force ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Dimensional Finite Element ◽  
Force Variation ◽  
Three Dimensional Finite Element

Abstract The effects of variations in stiffness and geometry on the nonuniformity of tires are investigated by using the finite element analysis. In order to evaluate tire uniformity, a three-dimensional finite element model of the tire with imperfections is developed. This paper considers how imperfections, such as variations in stiffness or geometry and run-out, contribute to detrimental effects on tire nonuniformity. It is found that the radial force variation of a tire with imperfections depends strongly on the geometrical variations of the tire.

Finite Element Analysis of Thermal Stresses in Circumferential Cast Clasps of Removable Partial Dentures

2007 ◽  
Vol 23 ◽  
pp. 229-232
Author(s):  
Liliana Sandu ◽  
Nicolae Faur ◽  
Cristina Bortun ◽  
Sorin Porojan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Stresses ◽  
Element Analysis ◽  
3 Dimensional ◽  
Thermal Changes ◽  
The Finite Element Analysis ◽  
Dimensional Finite Element ◽  
Back Action ◽  
Aggressive Effect

Several studies evaluated the removable partial dentures by the finite element analysis, but none of them evaluated thermal stresses. The purpose of the study was to explore the influence of thermal oral changes induced by hot/cold liquids and food on the circumferential cast clasps of removable partial dentures. A 3-dimensional finite element method was used to explore the temperature distribution, thermal stress and the influence of thermal changes on stresses and displacements of circumferential clasps during functions. Thermal variations induce stresses in dental clasps, high temperatures having a more aggressive effect than lower one. Cold liquids and food induce high stresses in the retentive clasp arms while hot ones in the occlusal rests of the clasps and for the back action clasp also in the minor connector. The study suggests the importance of consFigureidering thermal variations for stress analyses of the cast clasps.

Finite Element Study of the Effect of Load Sequence on the Fretting Wear

2020 ◽  
Author(s):  
Pankaj Dhaka ◽  
Raghu V. Prakash
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fretting Wear ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Low Load ◽  
Dimensional Finite Element ◽  
Wear Modelling ◽  
Load Sequence ◽  
Contact Parameters

Abstract Understanding the effect of load sequence is important in the context of a blade-disc dovetail joint in an aero-engine and many other such applications where, the mating surfaces undergo fretting wear under variable slip amplitude loading conditions. In the present work, a two-dimensional finite element analysis is carried out for a cylinder-on-plate configuration. The cylinder is modeled as deformable whereas the plate is modelled as rigid. An incremental wear modelling algorithm is used to model the wear of cylindrical pad while the plate is assumed as un-worn. This simulates a practical scenario where, generally one of the mating surfaces is sufficiently hardened or an interfacial harder/sacrificial element is inserted to restrict the wear to only one of the surfaces. A Fortran-based ABAQUS® subroutine UMESHMOTION is used to simulate the wear profile for the cylinder. A constant extrapolation technique is used to simulate 18000 cycles of fretting. The finite element analysis results are validated with the analytical solutions and literature data. The fretting wear modelling is carried out for two different slip amplitudes viz., 25 μm and 150 μm, to simulate the low and high slip amplitude loading respectively. Two blocks of alternate low and high slip amplitudes are applied to understand the influence of load sequence. Important contact parameters viz., contact pressure, contact stresses and contact slip are extracted. A comparison is made between the low-high and high-low load sequence based on the contact tractions and worn out profiles.

scholarly journals Evaluation of the Effects of the Chincup Appliance on the Craniofacial Structures by the Finite Element Analysis

2017 ◽  
Vol 7 ◽  
pp. 219-223
Author(s):  
Beril Demir Karamanli ◽  
Hülya Kılıçoğlu ◽  
Armagan Fatih Karamanli
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Fe Model ◽  
Analysis Method ◽  
Class Iii ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Clinical Changes

Aims The aim of this study is to evaluate the effects of the chincup appliance used in the treatment of Class III malocclusions, not only on the mandible or temporomandibular joint (TMJ) but also on all the craniofacial structures. Materials and Methods Chincup simulation was performed on a three-dimensional finite element (FE) model. 1000 g (500 g per side) force was applied in the direction of chin-condyle head. Nonlinear FE analysis was used as the numerical analysis method. Results By the application of chincup, stresses were distributed not only on TMJ or mandible but also on the circummaxillary sutures and other craniofacial structures. Conclusions Clinical changes obtained by chincup treatment in Class III malocclusions are not limited by only mandible. It was seen that also further structures were affected.

Finite Element Analysis of the Effect of Surface Hardening Depth in Port Crane Wheel

2011 ◽  
Vol 291-294 ◽  
pp. 3282-3286 ◽  
Author(s):  
Jiang Wei Wu ◽  
Peng Wang
Keyword(s):  
Finite Element ◽  
Surface Hardening ◽  
Three Dimensional ◽  
Element Model ◽  
Contact Stresses ◽  
Numerical Results ◽  
Element Analysis ◽  
Finite Element Software ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

In port crane industry, the surface hardening technique is widely used in order to improve the strength of wheel. But the hardening depth is chosen only by according to the experience, and the effect of different hardened depths is not studied theoretically. In this paper, the contact stresses in wheel with different hardening depth have been analyzed by applying three-dimensional finite element model. Based on this model, the ANSYS10.0 finite element software is used. The elastic wheel is used to verify the numerical results with the Hertz’s theory. Three different hardening depths, namely 10mm, 25mm and whole hardened wheel, under three different vertical loads were applied. The effect of hardening depth of a surface hardened wheel is discussed by comparing the contact stresses and contact areas from the numerical results.

The Finite Element Analysis of New Forged Coupler Knuckle

2013 ◽  
Vol 367 ◽  
pp. 122-125
Author(s):  
Guang Xin Wang ◽  
Xiang Shun Bu ◽  
Lin Jie Li ◽  
Li Li Zhu
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Direct Relationship ◽  
Element Analysis ◽  
Compression Load ◽  
The Finite Element Analysis ◽  
Simulation Results ◽  
Element Technique ◽  
Working Situation ◽  
Made In

As one of the most important load-bearing parts, coupler knuckle has a direct relationship with the safety in operation and reliability of the freight trains. A new forged coupler knuckle is made in order to meet the challenge to export ore train to Australia. Using the finite element technique, the stress characteristics of forged coupler knuckle under 1225kN load in tension and 1500kN compression load are evaluated. Simplify the load and boundary condition depend on the real working situation, the numerical simulation results coincide with experimental data.

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