simple contact twin

2009 ◽  
pp. 781-781
Keyword(s):  
Simple Contact

A Modular Race Tire Model Concerning Thermal and Transient Behavior using a Simple Contact Patch Description

2013 ◽  
Vol 41 (4) ◽  
pp. 232-246
Author(s):  
Timo Völkl ◽  
Robert Lukesch ◽  
Martin Mühlmeier ◽  
Michael Graf ◽  
Hermann Winner
Keyword(s):  
Load Distribution ◽  
Thermal Condition ◽  
Transient Behavior ◽  
Wheel Load ◽  
Contact Patch ◽  
Fundamental Parameters ◽  
Dry Conditions ◽  
Simple Contact ◽  
Tire Forces ◽  
Descriptive Set

ABSTRACT The potential of a race tire strongly depends on its thermal condition, the load distribution in its contact patch, and the variation of wheel load. The approach described in this paper uses a modular structure consisting of elementary blocks for thermodynamics, transient excitation, and load distribution in the contact patch. The model provides conclusive tire characteristics by adopting the fundamental parameters of a simple mathematical force description. This then allows an isolated parameterization and examination of each block in order to subsequently analyze particular influences on the full model. For the characterization of the load distribution in the contact patch depending on inflation pressure, camber, and the present force state, a mathematical description of measured pressure distribution is used. This affects the tire's grip as well as the heat input to its surface and its casing. In order to determine the thermal condition, one-dimensional partial differential equations at discrete rings over the tire width solve the balance of energy. The resulting surface and rubber temperatures are used to determine the friction coefficient and stiffness of the rubber. The tire's transient behavior is modeled by a state selective filtering, which distinguishes between the dynamics of wheel load and slip. Simulation results for the range of occurring states at dry conditions show a sufficient correlation between the tire model's output and measured tire forces while requiring only a simplified and descriptive set of parameters.

scholarly journals A Simple Contact Mechanics Model for Highly Strained Aqueous Surface Gels

2021 ◽  
Author(s):  
A. L. Chau ◽  
M. K. Cavanaugh ◽  
Y.-T. Chen ◽  
A. A. Pitenis
Keyword(s):  
Simple Model ◽  
Contact Mechanics ◽  
Contact Lenses ◽  
Radius Of Curvature ◽  
Winkler Foundation ◽  
Surface Layers ◽  
Mechanics Model ◽  
Soft Surface ◽  
Simple Contact ◽  
Highly Strained

Abstract Background Soft, biological, and bio-inspired materials are often compositionally heterogeneous and structurally anisotropic, and they frequently feature graded or layered organizations. This design complexity enables exceptional ranges in properties and performance yet complicates a fundamental understanding of the contact mechanics. Recent studies of soft gel layers have relied on Hertzian or Winkler foundation (“bed-of-springs”) models to characterize the mechanics but have found neither satisfactory. Objective The contact mechanics of soft gel layers are not yet fully understood. The aim of this work is to develop a simple contact mechanics model tailored for compositionally-graded materials with soft surface layers under high strains and deformations. Methods Concepts from polymer physics, fluid draining, and Winkler foundation mechanics are combined to develop a simple contact mechanics model which relates the applied normal force to the probe radius of curvature, elastic modulus, and thickness of soft surface layers subjected to high strains. Results This simple model was evaluated with two examples of graded surface gel layers spanning multiple length-scales, including commercially available contact lenses and stratified hydrogels. The model captures the nonlinear contact mechanics of highly strained soft aqueous gel layers more closely than either Hertz or Winkler foundation theory while simultaneously enabling a prediction for the thickness of the surface gel layer. Conclusion These results indicate that this simple model can adequately characterize the contact mechanics of highly strained soft aqueous gel layers.

Contact, Support, and Friction

1986 ◽  
Vol 29 (3) ◽  
pp. 337-355 ◽  
Author(s):  
Ann Leffler ◽  
Richard S. Krannich ◽  
Dair L. Gillespie
Keyword(s):  
Random Sample ◽  
Rural Areas ◽  
Contact Network ◽  
Personal Relations ◽  
Simple Contact

The networks literature has been bedeviled by an assumption that networks convey supportiveness to the exclusion of conflict. In this article, we discuss a method for distinguishing conflict, support, and simple contact network linkages in surveys. We then describe the results of applying this procedure to a random sample of households in several rural areas. We find that conflict does permeate personal relations. We also find that ego's and alters' genders affect the extent and type of frictions that engage them. We conclude by discussing implications of the findings for particular lines of research on stress and on community.

Mechanical response of marble epistyles under shear: numerical analysis using an experimentally validated model

2018 ◽  
Vol 27 (3-4) ◽  
Author(s):  
Ermioni D. Pasiou ◽  
Stavros K. Kourkoulis
Keyword(s):  
Numerical Model ◽  
Stress Field ◽  
Mechanical Response ◽  
Specific Problem ◽  
Shear Loading ◽  
Filling Material ◽  
Experimental Protocol ◽  
Loading Mode ◽  
Traditional Design ◽  
Simple Contact

AbstractThe mechanical response of the restored “connections” of the epistyles of the Parthenon Temple on the Acropolis of Athens is studied assuming that the interconnected epistyles are under shear loading mode. The study is implemented by taking advantage of a numerical model, properly validated on the basis of the data of a recent relative experimental protocol. The main difficulty while studying the specific problem is the co-existence of three materials of completely different mechanical behaviors, i.e. the brittle marble of the epistyles, the ductile titanium of the connector and the cement-based material filling the grooves of the marble in which the connector is placed. The interfaces of this three-material-complex are simulated as simple contact with friction, the coefficient of which is, also, experimentally determined. Taking advantage of the data provided by the numerical model the stress field developed in the connector and the surrounding marble volume is described. Moreover, the forces imposed by the connector on the surface of the groove are quantitatively determined. Furthermore, the model permits a quantitative comparison between the mechanical response of the interconnected epistyles in the presence or in the absence of the “relieving space”. It is definitely concluded that the alternative design of the “connections”, according to which a small portion of the connector’s web is left uncovered by the filling material (relieving space), offers serious advantages against the traditional design, in the direction of reducing the intensity of the stress field developed in the marble volume surrounding the connector, thus, contributing to the protection of the authentic building material of the monument in the case of overloading of the epistyles.

scholarly journals Damage progression from impact in layered glass modeled with peridynamics

2012 ◽  
Vol 2 (4) ◽  
Author(s):  
Florin Bobaru ◽  
Youn Ha ◽  
Wenke Hu
Keyword(s):  
Spatial Resolution ◽  
Damage Evolution ◽  
Dynamic Interaction ◽  
Stress Waves ◽  
Three Dimensions ◽  
Contact Conditions ◽  
Peridynamic Model ◽  
Simulation Results ◽  
Simple Contact ◽  
Computational Resources

AbstractDynamic fracture in brittle materials has been difficult to model and predict. Interfaces, such as those present in multi-layered glass systems, further complicate this problem. In this paper we use a simplified peridynamic model of a multi-layer glass system to simulate damage evolution under impact with a high-velocity projectile. The simulation results are compared with results from recently published experiments. Many of the damage morphologies reported in the experiments are captured by the peridynamic results. Some finer details seen in experiments and not replicated by the computational model due to limitations in available computational resources that limited the spatial resolution of the model, and to the simple contact conditions between the layers instead of the polyurethane bonding used in the experiments. The peridynamic model uncovers a fascinating time-evolution of damage and the dynamic interaction between the stress waves, propagating cracks, interfaces, and bending deformations, in three-dimensions.

Coexistence of different wear mechanisms in a simple contact

Wear ◽  
1977 ◽  
Vol 42 (1) ◽  
pp. 197-198 ◽  
Author(s):  
D. Play ◽  
M. Godet
Keyword(s):  
Wear Mechanisms ◽  
Simple Contact

Simple Contact Stiffness Model Validation for Tie Bolt Rotor Design With Butt Joints and Pilot Fits

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Aaron M. Rimpel ◽  
Matthew Leopard
Keyword(s):  
Natural Frequencies ◽  
Contact Stiffness ◽  
Butt Joint ◽  
Design Stage ◽  
Design Calculation ◽  
Butt Joints ◽  
Modeling Approach ◽  
Stiffness Model ◽  
Joint Location ◽  
Simple Contact

Abstract Tie bolt rotors for centrifugal compressors comprise multiple shaft components that are held together by a single tie bolt. The axial connections of these rotors—including butt joints, Hirth couplings, and Curvic couplings—exhibit a contact stiffness effect, which tends to lower the shaft bending frequencies compared to geometrically identical monolithic shafts. If not accounted for in the design stage, shaft bending critical speed margins can be compromised after a rotor is built. A previous paper had investigated the effect of tie bolt force on the bending stiffness of stacked rotor assemblies with butt joint interfaces, both with and without pilot fits. This previous work derived an empirical contact stiffness model and developed a practical finite element modeling approach for simulating the axial contact surfaces, which was validated by predicting natural frequencies for several test rotor configurations. The present work built on these previous results by implementing the same contact stiffness modeling approach on a real tie bolt rotor system designed for a high pressure centrifugal compressor application. Each joint location included two axial contact faces, with contact pressures up to five times higher than previously modeled, and a locating pilot fit. The free-free natural frequencies for different amounts of tie bolt preload force were measured, and the frequencies exhibited the expected stiffening behavior with increasing preload. However, a discontinuity in the data trend indicated a step-change increase in the contact stiffness. It was shown that this was likely due to one or more of the contact faces becoming fully engaged only after sufficient tie bolt force was applied. Finally, a design calculation was presented that can be used to estimate whether contact stiffness effects may be ignored, which could simplify rotor analyses if adequate contact pressure is used.

Simple Contact Stiffness Model Validation for Tie Bolt Rotor Design With Butt Joints and Pilot Fits

2019 ◽  
Author(s):  
Aaron M. Rimpel ◽  
Matthew Leopard
Keyword(s):  
Natural Frequencies ◽  
Contact Stiffness ◽  
Butt Joint ◽  
Design Stage ◽  
Design Calculation ◽  
Butt Joints ◽  
Modeling Approach ◽  
Stiffness Model ◽  
Joint Location ◽  
Simple Contact

Abstract Tie bolt rotors for centrifugal compressors comprise multiple shaft components that are held together by a single tie bolt. The axial connections of these rotors — including butt joints, Hirth couplings, and Curvic couplings — exhibit a contact stiffness effect, which tends to lower the shaft bending frequencies compared to geometrically identical monolithic shafts. If not accounted for in the design stage, shaft bending critical speed margins can be compromised after a rotor is built. A previous paper had investigated the effect of tie bolt force on the bending stiffness of stacked rotor assemblies with butt joint interfaces, both with and without pilot fits. This previous work derived an empirical contact stiffness model and developed a practical finite element modeling approach for simulating the axial contact surfaces, which was validated by predicting natural frequencies for several test rotor configurations. The present work built on these previous results by implementing the same contact stiffness modeling approach on a real tie bolt rotor system designed for a high pressure centrifugal compressor application. Each joint location included two axial contact faces, with contact pressures up to five times higher than previously modeled, and a locating pilot fit. The free-free natural frequencies for different amounts of tie bolt preload force were measured, and the frequencies exhibited the expected stiffening behavior with increasing preload. However, a discontinuity in the data trend indicated a step-change increase in the contact stiffness. It was shown that this was likely due to one or more of the contact faces becoming fully engaged only after sufficient tie bolt force was applied. Finally, a design calculation was presented that can be used to estimate whether contact stiffness effects may be ignored, which could simplify rotor analyses if adequate contact pressure is used.

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