Tire Contact Stresses and Their Effects on Instability Rutting of Asphalt Mixture Pavements: Three-Dimensional Finite Element Analysis

2003 ◽  
Vol 1853 (1) ◽  
pp. 150-156 ◽  
Author(s):  
Marc Novak ◽  
Bjorn Birgisson ◽  
Reynaldo Roque
Keyword(s):  
Asphalt Mixture ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Shear Stresses ◽  
Element Analysis ◽  
Surface Shear ◽  
Near Surface ◽  
Vertical Loading ◽  
Stress States

Instability rutting generally occurs within the top 2 in. of the asphalt layer when the structural properties of the asphalt concrete are inadequate to resist the stresses imposed on it. Several researchers have presented observations in attempts to explain instability rutting, but a clear identification of the mechanism does not exist. Stresses in the asphalt layer caused by measured tire interface stresses were analyzed in three dimensions by using finite elements to identify possible mechanisms for instability rutting. The analysis showed that radial tires produce high near-surface shear stresses at low confinements, which are not predicted with traditional uniform vertical loading conditions, in the region where instability rutting is known to occur. The resulting shear stresses tend to be shallower than for the uniformly loaded case, and they are focused in areas where instability rutting has been observed. The observed stress states imply that the characterization of instability rutting requires testing at these low confinement (and sometimes tensile) stress states, rather than at the higher stress states typically used in the strength characterization of mixtures.

convergent-beam diffraction from surfaces

1987 ◽  
Vol 45 ◽  
pp. 30-33
Author(s):  
J. A. Eades ◽  
A. E. Smith ◽  
D. F. Lynch
Keyword(s):  
Reciprocal Lattice ◽  
Three Dimensional ◽  
Grazing Incidence ◽  
Three Dimensions ◽  
Plane Figure ◽  
Transmission Electron ◽  
Convergent Beam ◽  
Beam Patterns ◽  
Beam Diffraction

It is quite simple (in the transmission electron microscope) to obtain convergent-beam patterns from the surface of a bulk crystal. The beam is focussed onto the surface at near grazing incidence (figure 1) and if the surface is flat the appropriate pattern is obtained in the diffraction plane (figure 2). Such patterns are potentially valuable for the characterization of surfaces just as normal convergent-beam patterns are valuable for the characterization of crystals.There are, however, several important ways in which reflection diffraction from surfaces differs from the more familiar electron diffraction in transmission.GeometryIn reflection diffraction, because of the surface, it is not possible to describe the specimen as periodic in three dimensions, nor is it possible to associate diffraction with a conventional three-dimensional reciprocal lattice.

Towards Predicting Relative Belt Edge Endurance With the Finite Element Method

1990 ◽  
Vol 18 (4) ◽  
pp. 216-235 ◽  
Author(s):  
J. De Eskinazi ◽  
K. Ishihara ◽  
H. Volk ◽  
T. C. Warholic
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Three Dimensional ◽  
The Finite Element Method ◽  
Shear Deformations ◽  
Element Analysis ◽  
Vertical Loading ◽  
Predicted Values ◽  
Element Method

Abstract The paper describes the intention of the authors to determine whether it is possible to predict relative belt edge endurance for radial passenger car tires using the finite element method. Three groups of tires with different belt edge configurations were tested on a fleet test in an attempt to validate predictions from the finite element results. A two-dimensional, axisymmetric finite element analysis was first used to determine if the results from such an analysis, with emphasis on the shear deformations between the belts, could be used to predict a relative ranking for belt edge endurance. It is shown that such an analysis can lead to erroneous conclusions. A three-dimensional analysis in which tires are modeled under free rotation and static vertical loading was performed next. This approach resulted in an improvement in the quality of the correlations. The differences in the predicted values of various stress analysis parameters for the three belt edge configurations are studied and their implication on predicting belt edge endurance is discussed.

Three-dimensional finite element analysis comparative model of tooth–implant nonrigid fixation

SIMULATION ◽  
2020 ◽  
pp. 003754972097278
Author(s):  
Tigran A Muradyan ◽  
Nshan A Muradyan ◽  
Sergey V Verlinski ◽  
Anna Yu Poghosyan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Distribution ◽  
Three Dimensional ◽  
Rigid Fixation ◽  
Element Analysis ◽  
Validation Data ◽  
Vertical Loading ◽  
N Loading ◽  
Three Dimensional Finite Element

Connecting implants with teeth is sometimes considered for the support of prostheses in partial edentulism, especially in periodontally compromised and surgical treated patients. The aim of this study is the presentation of a model of tooth–implant nonrigid fixation in comparison with implant–implant and implant–tooth rigid fixation by three-dimensional (3D) finite element analysis. As a model, a situation with a mandibular second premolar and two molars edentulism was selected. Two implantation options with three prosthetics designs were considered. The comparative analysis of stress and strain distribution values under vertical 100 and 200 N loading was performed. The highest peri-implant crestal bone stress distribution was observed in the model with the implant–tooth rigid fixation with 200 N vertical loading with results of 136.56 MPa. In the model with implant–tooth nonrigid fixation, the maximum strain value was observed in the tooth–connector zone and the stress distribution was higher in the connectors and the prosthesis pontic zone, with a maximal value of 27.77 MPa. The design of a tooth–implant fixed denture could be suggested as a method of choice for rehabilitation of the posterior edentulous segment in cases when only one distal implant could be installed. Further clinical research is required to obtain reliable validation data for the proposed method.

Local bond order parameters for accurate determination of crystal structures in two and three dimensions

2018 ◽  
Vol 20 (42) ◽  
pp. 27059-27068 ◽  
Author(s):  
Hossein Eslami ◽  
Parvin Sedaghat ◽  
Florian Müller-Plathe
Keyword(s):  
Crystal Structures ◽  
Bond Order ◽  
Accurate Determination ◽  
Three Dimensional ◽  
Order Parameters ◽  
Three Dimensions ◽  
Local Order ◽  
Crystalline Structures

Local order parameters for the characterization of liquid and different two- and three-dimensional crystalline structures are presented.

Three-Dimensional Strain-Based Model for the Severity Characterization of Dented Pipelines

2018 ◽  
Vol 1 (3) ◽  
Author(s):  
Chike Okoloekwe ◽  
Muntaseer Kainat ◽  
Doug Langer ◽  
Sherif Hassanien ◽  
J.J. Roger Cheng ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Numerical Models ◽  
Three Dimensional ◽  
Strain Analysis ◽  
Computation Time ◽  
Order Continuity ◽  
Element Analysis ◽  
The Mathematical Model ◽  
Derivatives Of

Oil and gas pipelines traverse long distances and are often subjected to mechanical forces that result in permanent distortion of its geometric cross section in the form of dents. In order to prioritize the repair of dents in pipelines, dents need to be ranked in order of severity. Numerical modeling via finite element analysis (FEA) to rank the dents based on the accumulated localized strain is one approach that is considered to be computationally demanding. In order to reduce the computation time with minimal effect to the completeness of the strain analysis, an approach to the analytical evaluation of strains in dented pipes based on the geometry of the deformed pipe is presented in this study. This procedure employs the use of B-spline functions, which are equipped with second-order continuity to generate displacement functions, which define the surface of the dent. The strains associated with the deformation can be determined by evaluating the derivatives of the displacement functions. The proposed technique will allow pipeline operators to rapidly determine the severity of a dent with flexibility in the choice of strain measure. The strain distribution predicted using the mathematical model proposed is benchmarked against the strains predicted by nonlinear FEA. A good correlation is observed in the strain contours predicted by the analytical and numerical models in terms of magnitude and location. A direct implication of the observed agreement is the possibility of performing concise strain analysis on dented pipes with algorithms relatively easy to implement and not as computationally demanding as FEA.

Topological characterization of deterministic chaos: enforcing orientation preservation

2007 ◽  
Vol 366 (1865) ◽  
pp. 559-567 ◽  
Author(s):  
Marc Lefranc ◽  
Pierre-Emmanuel Morant ◽  
Michel Nizette
Keyword(s):  
Periodic Orbits ◽  
Topological Analysis ◽  
Three Dimensional ◽  
Deterministic Chaos ◽  
Three Dimensions ◽  
Unstable Periodic Orbits ◽  
Topological Characterization ◽  
Triangulated Surfaces ◽  
Theoretic Characterization

The determinism principle, which states that dynamical state completely determines future time evolution, is a keystone of nonlinear dynamics and chaos theory. Since it precludes that two state space trajectories intersect, it is a core ingredient of a topological analysis of chaos based on a knot-theoretic characterization of unstable periodic orbits embedded in a strange attractor. However, knot theory can be applied only to three-dimensional systems. Still, determinism applies in any dimension. We propose an alternative framework in which this principle is enforced by constructing an orientation-preserving dynamics on triangulated surfaces and find that in three dimensions our approach numerically predicts the correct topological entropies for periodic orbits of the horseshoe map.

Stress Distribution in Porous Ceramic Bodies During Binder Burnout

2002 ◽  
Vol 69 (4) ◽  
pp. 497-501 ◽  
Author(s):  
Z. C. Feng ◽  
B. He ◽  
S. J. Lombardo
Keyword(s):  
Pore Space ◽  
Porous Ceramic ◽  
Three Dimensional ◽  
The Body ◽  
Shear Stresses ◽  
Element Analysis ◽  
Porous Bodies ◽  
Mechanics Model ◽  
Binder Burnout ◽  
Normal And Shear Stresses

A model has been developed for describing the stresses that arise during binder burnout in three-dimensional porous bodies. The pressure gradient that arises from the decomposition of binder in the pore space is treated as an equivalent body force. For input into the mechanics model, the pressure distribution is obtained from the analytical solution for three-dimensional porous bodies with anisotropic permeability. The normal and shear stresses are then calculated from finite element analysis for bodies of parallelepiped geometry. In general, the normal stresses occur at the center of the body and are an order of magnitude larger than the shear stresses. Both the normal and shear stresses depend on the body size, the body geometry, and on the permeability.

Blood Flow in Stented Arteries: A Parametric Comparison of Strut Design Patterns in Three Dimensions

2005 ◽  
Vol 127 (4) ◽  
pp. 637-647 ◽  
Author(s):  
Yong He ◽  
Nandini Duraiswamy ◽  
Andreas O. Frank ◽  
James E. Moore
Keyword(s):  
Fluid Dynamics ◽  
Flow Direction ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Three Dimensions ◽  
Low Flow ◽  
Radius Of Curvature ◽  
Shear Stresses ◽  
Stent Design ◽  
Flow Conditions

Background: Restenosis after stent implantation varies with stent design. Alterations in secondary flow patterns and wall shear stress (WSS) can modulate intimal hyperplasia via their effects on platelet and inflammatory cell transport toward the wall, as well as direct effects on the endothelium. Method of Approach: Detailed flow characteristics were compared by estimating the WSS in the near-strut region of realistic stent designs using three-dimensional computational fluid dynamics (CFD), under pulsatile high and low flow conditions. The stent geometry employed was characterized by three geometric parameters (axial strut pitch, strut amplitude, and radius of curvature), and by the presence or lack of the longitudinal connector. Results: Stagnation regions were localized around stent struts. The regions of low WSS are larger distal to the strut. Under low flow conditions, the percentage restoration of mean axial WSS between struts was lower than that for the high flow by 10–12%. The largest mean transverse shear stresses were 30–50% of the largest mean axial shear stresses. The percentage restoration in WSS in the models without the longitudinal connector was as much as 11% larger than with the connector. The mean axial WSS restoration between the struts was larger for the stent model with larger interstrut spacing. Conclusion: The results indicate that stent design is crucial in determining the fluid mechanical environment in an artery. The sensitivity of flow characteristics to strut configuration could be partially responsible for the dependence of restenosis on stent design. From a fluid dynamics point of view, interstrut spacing should be larger in order to restore the disturbed flow; struts should be oriented to the flow direction in order to reduce the area of flow recirculation. Longitudinal connectors should be used only as necessary, and should be parallel to the axis. These results could guide future stent designs toward reducing restenosis.

Test Methods for Hyperelastic Characterization of Rubber4

2009 ◽  
Vol 37 (3) ◽  
pp. 165-186 ◽  
Author(s):  
R. Kupchella ◽  
J. Kidney ◽  
W. Hutchison
Keyword(s):  
Three Dimensional ◽  
Test Methods ◽  
Biaxial Stress ◽  
Image Correlation ◽  
Optical Methods ◽  
Filled Rubber ◽  
Rubber Compounds ◽  
Stress States ◽  
Property Changes

Abstract Optical methods using digital image correlation (DIC) are utilized in developing rubber constitutive tests. Two and three dimensional DIC systems are employed to measure strains on rubber specimens subjected to uniaxial, planar, and biaxial stress states. A special membrane inflation test was developed and is described for providing the biaxial constitutive data. Deformation-induced material property changes for the three modes of testing are quantified using a concept based on energy dissipation. The constitutive test strain ranges for each of the three modes are separately selected to equalize the material states. The methodology is applied to filled rubber compounds in order to characterize them in terms of hyperelastic behavior. Evaluation and comparison of several common hyperelastic models are given, and application to finite element modeling of a structural rubber specimen is described.

Sign in / Sign up

Export Citation Format

Share Document