Hoop stresses in the con-rod small end

2005 ◽  
Vol 219 (11) ◽  
pp. 1331-1345 ◽  
Author(s):  
A Strozzi ◽  
F De Bona
Keyword(s):  
Hoop Stress ◽  
Wide Spectrum ◽  
Three Dimensional ◽  
Theory Of Elasticity ◽  
Analytical Models ◽  
Pertinent Literature ◽  
Dimensional Finite Element ◽  
Initial Clearance ◽  
Three Dimensional Finite Element ◽  
Hoop Stresses

Having in mind con-rods for motorbike and car engines, and spurred by the disagreements evidenced in the pertinent literature, the maximum circumferential stresses within the small end are investigated analytically, photoelastically, and numerically. The analytical models are based upon a plane assumption, and they adopt both beam and theory of elasticity idealizations. The plane photoelastic study concentrates on small ends with outer to inner radii ratios ranging from 1.2 to 1.5. A plane numerical model aimed at thoroughly mimicking the pin ovalization is developed, and a design chart of the peak hoop stress within the small end is provided for a wide spectrum of small end and pin geometries, for zero initial clearance. Such diagrams allow a prompt preliminary dimensioning of the small end to be carried out, which may be refined by effecting a three-dimensional finite element study of the specific con-rod geometry. The consequences of an initial clearance between small end bore and gudgeon pin are examined for selected geometries, and three-dimensional aspects are explored for specific con-rod shapes.

The Influence of Geometrical Distortions of Three-Dimensional Finite Elements, Used to Model Proximal Femoral Bone

1995 ◽  
Vol 209 (1) ◽  
pp. 31-36 ◽  
Author(s):  
J Vander Sloten ◽  
G van der Perre
Keyword(s):  
Proximal Femur ◽  
Hoop Stress ◽  
Three Dimensional ◽  
Element Model ◽  
Bending Stress ◽  
Different Types ◽  
Dimensional Finite Element ◽  
Middle Node ◽  
Three Dimensional Finite Element ◽  
Hoop Stresses

A realistic three-dimensional finite element model of the proximal femur requires the use of irregularly shaped elements to represent this geometry, unless the geometry is considerably simplified. The authors have investigated the influence of different types of element distortions upon the accuracy of two stresses which are relevant in the proximal femur: the bending stress and the tangential (hoop) stress. While most angular and geometric distortions did not influence the bending stress significantly, the position of the middle node on the edge of a quadratic element was very critical, as were some types of element skewness. The hoop stresses can only be calculated accurately if the geometry is modelled as well as possible by a cylinder, and not by a cone.

Examination of Response of a Skewed Steel Bridge Superstructure During Deck Placement

2003 ◽  
Vol 1845 (1) ◽  
pp. 66-75 ◽  
Author(s):  
Elizabeth K. Norton ◽  
Daniel G. Linzell ◽  
Jeffrey A. Laman
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Element Model ◽  
Analytical Models ◽  
Levels Of Analysis ◽  
Steel Bridge ◽  
Bridge Superstructure ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Skewed Bridge

The response of a 74.45-m (244-ft 0-in.) skewed bridge to the placement of the concrete deck was monitored to compare measured and predicted behavior. This comparison was completed to ( a) determine theoretical deflections and rotations with analytical models for comparison to actual deformations monitored during construction; ( b) compare the results of various levels of analysis to determine the adequacy of the methods; and ( c) examine variations on the concrete placement sequence to determine the most efficient deck placement methods. Two levels of analysis were used to achieve the objectives. Level 1 was a two-dimensional finite element grillage model analyzed with STAAD/Pro. Level 2 was a three-dimensional finite element model analyzed with SAP2000. These studies are discussed and findings are presented.

Prediction of the yielding behaviour of ductile porous materials through computational homogenization

2018 ◽  
Vol 35 (2) ◽  
pp. 604-621
Author(s):  
Rodrigo Pinto Carvalho ◽  
Igor A. Rodrigues Lopes ◽  
Francisco M. Andrade Pires
Keyword(s):  
Three Dimensional ◽  
Yield Locus ◽  
Analytical Models ◽  
Finite Element Models ◽  
Content Type ◽  
Ductile Materials ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Void Geometry ◽  
The Impact

Purpose The purpose of this paper is to predict the yield locus of porous ductile materials, evaluate the impact of void geometry and compare the computational results with existing analytical models. Design/methodology/approach A computational homogenization strategy for the definition of the elasto-plastic transition is proposed. Representative volume elements (RVEs) containing single-centred ellipsoidal voids are analysed using three-dimensional finite element models under the geometrically non-linear hypothesis of finite strains. Yield curves are obtained by means of systematic analysis of RVEs considering different kinematical models: linear boundary displacements (upper bound), boundary displacement fluctuation periodicity and uniform boundary traction (lower bound). Findings The influence of void geometry is captured and the reduction in the material strength is observed. Analytical models usually overestimate the impact of void geometry on the yield locus. Originality/value This paper proposes an alternative criterion for porous ductile materials and assesses the accuracy of analytical models through the simulation of three-dimensional finite element models under geometrically non-linear hypothesis.

External Longitudinal Flaws in Pipes Under Complex Loading

2000 ◽  
Vol 123 (1) ◽  
pp. 139-145 ◽  
Author(s):  
Roberto Brighenti
Keyword(s):  
Thermal Stresses ◽  
Superposition Principle ◽  
Three Dimensional ◽  
Complex Loading ◽  
Stress Distributions ◽  
Power Series Expansions ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Hoop Stresses ◽  
Crack Faces

A round pipe with an external longitudinal surface flaw is assumed to be subjected to different types of elementary hoop stress distributions acting perpendicular to the crack faces. The stress intensity factors (SIFs) along the crack front for such elementary cases are determined through the three-dimensional finite element method. Then these results are used to compute approximate values of SIFs in the case of complex loadings (such as internal pressure, thermal stresses, residual stresses due to plasticization, etc.), by employing both the superposition principle and the power series expansions of the actual hoop stresses. Thick and thin-walled pipes are examined, and some results are compared with those presented by other authors.

Effective elastic moduli of metal honeycombs manufactured using selective laser melting

2020 ◽  
Vol 26 (5) ◽  
pp. 971-980 ◽  
Author(s):  
Rafid Hussein ◽  
Sudharshan Anandan ◽  
Myranda Spratt ◽  
Joseph W. Newkirk ◽  
K. Chandrashekhara ◽  
...  
Keyword(s):  
Strain Energy ◽  
Elastic Moduli ◽  
Three Dimensional ◽  
Analytical Models ◽  
Effective Elastic Moduli ◽  
Effective Moduli ◽  
Content Type ◽  
Out Of Plane ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Purpose Honeycomb cellular structures exhibit unique mechanical properties such as high specific strength, high specific stiffness, high energy absorption and good thermal and acoustic performance. This paper aims to use numerical modeling to investigate the effective elastic moduli, in-plane and out-of-plane, for thick-walled honeycombs manufactured using selective laser melting (SLM). Design/methodology/approach Theoretical predictions were performed using homogenization on a sample scale domain equivalent to the as-manufactured dimensions. A Renishaw AM 250 machine was used to manufacture hexagonal honeycomb samples with wall thicknesses of 0.2 to 0.5 mm and a cell size of 3.97 mm using 304 L steel powder. The SLM-manufactured honeycombs and cylindrical test coupons were tested using flatwise and edgewise compression. Three-dimensional finite element and strain energy homogenization were conducted to determine the effective elastic properties, which were validated by the current experimental outcomes and compared to analytical models from the literature. Findings Good agreement was found between the results of the effective Young’s moduli ratios numerical modeling and experimental observations. In-plane effective elastic moduli were found to be more sensitive to geometrical irregularity compared to out-of-plane effective moduli, which was confirmed by the analytical models. Also, it was concluded that thick-walled SLM manufactured honeycombs have bending-dominated in-plane compressive behavior and a stretch-dominated out-of-plane compressive behavior, which matched well with the simulation and numerical models predictions. Originality/value This work uses three-dimensional finite element and strain energy homogenization to evaluate the effective moduli of SLM manufactured honeycombs.

Assessment of Analytical Predictions for Radial Growth of Rotating Labyrinth Seals

2018 ◽  
Vol 35 (3) ◽  
pp. 265-279 ◽  
Author(s):  
Sivakumar Subramanian ◽  
A. S. Sekhar ◽  
B. V. S. S. S. Prasad
Keyword(s):  
Rotational Speed ◽  
Radial Growth ◽  
Three Dimensional ◽  
Labyrinth Seal ◽  
Analytical Models ◽  
Length Ratio ◽  
Labyrinth Seals ◽  
High Rotational Speed ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Abstract Radial growth predictions of rotating labyrinth seals are conventionally obtained from one-dimensional analytical models. However, these predictions quantitatively differ within themselves by about 5-500 %. Simulations using three-dimensional finite element method (FEM) are carried out in this paper for a typical labyrinth seal, subjected to high rotational speed and temperature, for a range of radius-to-length ratio of the rotor. Taking the predicted values by FEM as reference, four analytical models are assessed and their errors are quantified. These errors are found to be independent of rotational speed and temperature but significantly vary with the radius-to-length ratio of the rotor. Based on this finding, simple analytical models, together with correction factor charts, are suggested.

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%.

Closed Analytical Expressions for Stress Distributions in Two-Layer Cylinders and Their Application to Offshore Lined and Clad Pipes

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Knut Vedeld ◽  
Håvar A. Sollund ◽  
Jostein Hellesland
Keyword(s):  
Plane Strain ◽  
Thermal Loading ◽  
Three Dimensional ◽  
Engineering Practice ◽  
Start Up ◽  
Clad Layer ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Hoop Stresses ◽  
Analytical Expressions

Closed-form analytical expressions are derived for the displacement field and corresponding stress state in two-layer cylinders subjected to pressure and thermal loading. Solutions are developed both for cylinders that are fully restrained axially (plane strain) and for cylinders that are axially loaded and spring-mounted. In the latter case, it is assumed that the combined two-layer cross section remains plane after deformation (generalized plane strain). The analytical solutions are verified by means of detailed three-dimensional finite element (FE) analyses, and they are easily implemented in, and suitable for, engineering applications. The chosen axial boundary conditions are demonstrated to be particularly relevant for pipeline and piping applications. By applying the exact solutions derived in the present study to typical offshore lined or clad pipelines, it is demonstrated that thermal expansion of the liner or clad layer may cause higher tensile hoop stresses in the pipe steel wall than accounted for in current engineering practice. It is shown that repeated cycles of start-up and shut-down phases for lined or clad pipelines cause significant plastic stress cycles in liners or claddings, which may pose a risk to the integrity of such pipelines.

Calculating Arc Length and Curvature of Helical Elements in Bent Cables and Umbilicals Using Fourier Series

2017 ◽  
Author(s):  
Magnus Komperød
Keyword(s):  
Fourier Series ◽  
Three Dimensional ◽  
Numerical Calculations ◽  
Analytical Models ◽  
Arc Length ◽  
Convergence Properties ◽  
Analytical Approximations ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Arc Lengths

Mechanical cable analyses range from simple hand calculations to complex, three-dimensional finite element analyses. This paper considers numerical calculations of analytical models as an attractive compromise between these extremities. The paper derives numerical calculations of the arc lengths and the local bending curvatures of helical elements in bent cables and umbilicals, and compares the results with analytical approximations found in the scientific literature. The numerical calculations are highly efficient, requiring only a very few function evaluations to give excellent accuracy. On today’s PCs and laptops the calculations require only a few milliseconds CPU time. The excellent convergence properties of Fourier series for smooth, periodic functions are used to achieve these favorable results. In addition to high accuracy, the numerical calculations disclose behaviors that are not captured by the analytical approximations.

scholarly journals Evaluating the Design Criteria for Light Embankment Piling: Timber Piles in Road and Railway Foundations

2021 ◽  
Vol 12 (1) ◽  
pp. 166
Author(s):  
Per Gunnvard ◽  
Hans Mattsson ◽  
Jan Laue
Keyword(s):  
Three Dimensional ◽  
Design Guidelines ◽  
Analytical Models ◽  
Current Standard ◽  
Fe Modelling ◽  
Fe Simulations ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Timber Piles ◽  
Piled Embankments

Three-dimensional finite element (FE) simulations were performed to further develop the Swedish design guidelines for geogrid-reinforced timber pile-supported embankments, also known as lightly piled embankments. Lightly piled embankments are constructed mainly in areas which typically have highly compressible soils, and the method utilises untreated timber piles as its key feature. The timber piles are installed in a triangular arrangement instead of the more common square arrangement, with a centre-to-centre distance of 0.8–1.2 m. The aim of this study was to evaluate the current standard using FE modelling setups with square and triangular pile arrangements with varying centre-to-centre distances, based on a typical road foundation case. The evaluation mainly focused on comparing the embankment settlements, as well as the load and stress distribution in the embankment, the piles and the geosynthetic reinforcement. As part of the evaluation, a state-of-the-art study was done on international design guidelines and analytical models. From the FE simulations, no evident difference in mechanical behaviour was found between the triangular and square piling patterns. The maximum allowed centre-to-centre distance between piles can potentially be increased to 1.4 m, decreasing the number of piles by as much as one third.

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