Surface Normal Thermoelastic Displacement in Moving Rough Contacts

2003 ◽  
Vol 125 (4) ◽  
pp. 862-868 ◽  
Author(s):  
Shuangbiao Liu ◽  
Qian Wang ◽  
Stephen J. Harris
Keyword(s):  
Contact Pressure ◽  
Mutual Influence ◽  
Frictional Heating ◽  
Numerical Procedure ◽  
Contact Problems ◽  
Frictional Heat ◽  
Elastic Displacement ◽  
Surface Normal ◽  
Moving Bodies ◽  
Thermoelastic Displacement

Computing the thermoelastic displacement of three-dimensional stationary or moving bodies subject to frictional heating is an essential numerical procedure for the complex modeling of the contact of tribological components. Surface Roughness inevitably causes the irregularity of the frictional heat distribution, and thus complicates the process of the numerical simulation of contact problems. The surface normal thermoelastic displacement has been studied in previous papers for either stationary bodies with irregularly distributed heat or moving bodies with regularly distributed heat. In this work, irregularly distributed frictional heat is applied on the surface of a moving body. Temperature and surface normal thermoelastic displacement are solved by using an efficient numerical procedure involving the discrete convolution and fast Fourier transform algorithm and frequency response functions. The thermoelastic displacement due to frictional heat that is proportional to the contact pressure is comparable to the elastic displacement caused by the contact pressure and is not sensitive to the roughness texture. The transient performance of multiple heat sources with different shapes, as well as the mutual influence, is also studied.

An Adaptive EFG-FE Computational Model for Thermal Elasto-Plastic Frictional Contact Problems

2008 ◽  
Vol 33-37 ◽  
pp. 821-826
Author(s):  
Zheng Zhang ◽  
Geng Liu ◽  
Tian Xiang Liu
Keyword(s):  
Frictional Heating ◽  
Contact Problems ◽  
Coupling Model ◽  
Adaptive Refinement ◽  
Frictional Heat ◽  
Plastic Behavior ◽  
Initial Stiffness ◽  
Gradient Based ◽  
Local Adaptive Refinement ◽  
The Cost

An adaptive meshless element-free Galerkin-finite element (EFG-FE) coupling model for thermal elasto-plastic contact problems is developed to investigate the influences of the steady-state frictional heating on the contact performance of two contacting bodies. The thermal elasto-plastic contact problems using the initial stiffness method is presented. The local adaptive refinement strategy and the strain energy gradient-based error estimation for EFG-FE coupling method are combined. The adaptive meshless model takes into account the temperature variation, micro plastic flow, and the coupled thermo-elasto-plastic behavior of the materials, considering the strain-hardening property of the materials and temperature-dependent yield strength. The adaptive model is verified through the contact analysis of a cylinder with an elasto-plastic plane. The thermal effects on the contact pressure, stresses distributions with certain frictional heat inputs are studied. The results show that the accuracy of the solutions from the adaptive refinement model is satisfactory but the cost of the CPU time is much less than that for the uniform refinement calculation.

scholarly journals The Indentation Rolling Resistance in Belt Conveyors: A Model for the Viscoelastic Friction

Lubricants ◽  
2019 ◽  
Vol 7 (7) ◽  
pp. 58 ◽  
Author(s):  
Nicola Menga ◽  
Francesco Bottiglione ◽  
Giuseppe Carbone
Keyword(s):  
Contact Problem ◽  
Finite Thickness ◽  
Numerical Procedure ◽  
Contact Problems ◽  
Accurate Solution ◽  
Rolling Contact ◽  
Viscoelastic Layer ◽  
Force Coefficient ◽  
Belt Conveyors ◽  
Energy Dissipated

In this paper, we study the steady-state rolling contact of a linear viscoelastic layer of finite thickness and a rigid indenter made of a periodic array of equally spaced rigid cylinders. The viscoelastic contact model is derived by means of Green’s function approach, which allows solving the contact problem with the sliding velocity as a control parameter. The contact problem is solved by means of an accurate numerical procedure developed for general two-dimensional contact geometries. The effect of geometrical quantities (layer thickness, cylinders radii, and cylinders spacing), material properties (viscoelastic moduli, relaxation time) and operative conditions (load, velocity) are all investigated. Physical quantities typical of contact problems (contact areas, deformed profiles, etc.) are calculated and discussed. Special emphasis is dedicated to the viscoelastic friction force coefficient and to the energy dissipated per unit time. The discussion is focused on the role played by the deformation localized at the contact spots and the one in the bulk of the thin layer, due to layer bending. The model is proposed as an accurate solution for engineering applications such as belt conveyors, in which the energy dissipated on the rolling contact of idle rollers can, in some cases, be by far the most important contribution to their energy consumption.

Thermal Distortion of an Anisotropic Elastic Half-Plane and its Application in Contact Problems Including Frictional Heating

2005 ◽  
Vol 128 (1) ◽  
pp. 32-39 ◽  
Author(s):  
Yuan Lin ◽  
Timothy C. Ovaert
Keyword(s):  
Heat Flux ◽  
Half Plane ◽  
Frictional Heating ◽  
Contact Problems ◽  
Local Heat ◽  
Extended Version ◽  
Parabolic Profile ◽  
Local Heat Flux ◽  
Anisotropic Elastic ◽  
Thermoelastic Contact Problem

The thermal surface distortion of an anisotropic elastic half-plane is studied using the extended version of Stroh’s formalism. In general, the curvature of the surface depends both on the local heat flux into the half-plane and the local temperature variation along the surface. However, if the material is orthotropic, the curvature of the surface depends only on the local heat flux into the half-plane. As a direct application, the two-dimensional thermoelastic contact problem of an indenter sliding against an orthotropic half-plane is considered. Two cases, where the indenter has either a flat or a parabolic profile, are studied in detail. Comparisons with other available results in the literature show that the present method is correct and accurate.

Approximate Analytical Model for Hertzian Elliptical Wheel/Rail or Wheel/Crossing Contact Problems

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
F. D. Fischer ◽  
M. Wiest
Keyword(s):  
Contact Pressure ◽  
Contact Problems ◽  
Hertzian Contact ◽  
Contact Theory ◽  
Technical Accuracy ◽  
Elliptical Contact ◽  
Current Approximation ◽  
Analytical Expressions ◽  
Maximum Contact ◽  
Hertzian Contact Theory

The Hertzian contact theory is approximated according to a concept by Tanaka (2001, “A New Calculation Method of Hertz Elliptical Contact Pressure,” ASME J. Tribol., 123, pp. 887–889) yielding simple analytical expressions for the elliptical semi-axes, the maximum contact pressure, the mutual approach and the contact spring constant. Several configurations are compared using the exact Hertz theory and the current approximation. The results agree within technical accuracy.

Three-Dimensional Finite Element Analysis of Pipe Flange Connections: The Case of Using Compressed Asbestos Sheet Gasket

2002 ◽  
Author(s):  
Tomohiro Takaki ◽  
Toshimichi Fukuoka
Keyword(s):  
Contact Pressure ◽  
Three Dimensional ◽  
Numerical Procedure ◽  
Bending Moment ◽  
Elastic Interaction ◽  
Bearing Surface ◽  
Element Analysis ◽  
Bolt Stress ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

The most important factor for the leakage problem of pipe flange connections is considered to be contact pressure distribution at the gasket bearing surface in service. In this study, the mechanical behaviors of the pipe flange connection are evaluated using FEM as a three-dimensional contact problem, in which a gasket is modeled as a nonlinear one-dimensional gasket element. Here, the contact pressure distributions at the gasket bearing surface and the variations of the bolt stress are estimated under uniform bolt preloads or nonuniform ones due to the elastic interaction during bolting up. The numerical procedure proposed here can successively deal with the processes of bolt-up, applying inner pressure and applying bending moment. The analytical objects are pipe flanges specified in JIS B 2238 with compressed asbestos sheet gaskets being inserted. The validity of the numerical method is ascertained by experiment.

Evaluation of Young’s modulus of construction materials by instrumented indentation using a ball indenter

2021 ◽  
Vol 87 (8) ◽  
pp. 64-68
Author(s):  
V. M. Matyunin ◽  
A. Yu. Marchenkov ◽  
N. Abusaif ◽  
M. V. Goryachkina ◽  
R. V. Rodyakina ◽  
...  
Keyword(s):  
Young’S Modulus ◽  
Young's Modulus ◽  
High Surface ◽  
Construction Materials ◽  
Contact Problems ◽  
Indentation Load ◽  
Test Material ◽  
Elastic Displacement ◽  
Large Radius ◽  
Instrumented Indentation

Methods for evaluation of Young’s modulus (Em) of structural materials by instrumented indentation using ball indenter have been considered. All these techniques are based on the solution of elastic contact problems performed by H. Hertz. It has been shown that registration of the initial elastic region in the «load – displacement» indentation diagram provides the Em determination for metals and alloys. However, it is necessary to evaluate accurately the elastic compliance of a device, to use an indenter with a large radius R, and ensure a high surface quality of the test material in advance. Methods for Em determation, when indentation diagrams are recorded in the elastoplastic indentation region, should include the effect of plastic deformation on the elastic displacement calculated by H. Hertz expression. However, it appeared essential to determine the relation between the elastic αel and plastic h components of the total elastoplastic displacement α and the elastic displacement α0 estimated by H. Hertz expression for a definite indentation load. A close correlation between α0 and αel is revealed for steels, aluminum, magnesium, and titanium alloys when using indenters with a radius of R = 0.2 – 5 mm (diameter D = 0.4 – 10 mm) and maximum indentation load Fmax = 47 – 29430 N (4.8 – 3000 kgf). It is also shown that a gradual decrease in Em is observed with an increase in R(D) at the same degree of loading F/D2 for the same material. This fact was explained by the scale factor effect.

scholarly journals A Wear Simulation Method for Mechanical Face Seals under Friction Instability Conditions

2020 ◽  
Vol 10 (8) ◽  
pp. 2875
Author(s):  
Wentao He ◽  
Shaoping Wang ◽  
Chao Zhang ◽  
Xi Wang ◽  
Di Liu
Keyword(s):  
Contact Pressure ◽  
Torsional Stiffness ◽  
Frictional Heat ◽  
Axial Stiffness ◽  
Asperity Contact ◽  
Wear Simulation ◽  
Time Rate ◽  
Wear Time ◽  
Face Seals ◽  
Non Gaussian

Mechanical face seals are crucial components of automotive cooling water pumps and affect the safe operation of the pump. This article focuses on the effect of friction instabilities on the wear of the seals. Friction instabilities, such as stick-slip, occur when the axle is decelerated or operated at a low speed. Based on previous studies, a simulation model is proposed of a mechanical face seal that considers the interaction of asperities of non-Gaussian surfaces and the heat transfer between the sealing rings. According to the Archard wear equation, a numerical wear simulation is performed, and the wear distance rate and wear time rate are obtained. A comparison of the contact pressure of the Gaussian and non-Gaussian surfaces indicates that the latter is more likely to generate high contact pressure, thereby producing more significant wear. The viscous shear heat and frictional heat due to asperity contact decrease with an increase in the thickness of the tapered film. As the shaft decelerates, the wear distance rate increases with an increase in the axial stiffness. The axial damping only affects the duration of the oscillations. The wear time rate decreases with an increase in the torsional stiffness and torsional damping. The results of this research provide guidelines for estimating the wear of mechanical seals when friction instabilities occur.

Numerical investigation of frictional heating effect on the earthquake faulting based on the Ruina- and Chester-Higgs- models

2020 ◽  
Author(s):  
Yaqi Gao ◽  
Baoping Shi
Keyword(s):  
Temperature Effect ◽  
Temporal Evolution ◽  
Initial Conditions ◽  
Frictional Heating ◽  
Higgs Model ◽  
Fault System ◽  
Frictional Heat ◽  
Recurrence Time ◽  
Generation Model ◽  
Frictional Strength

<p>Rate- and state-dependent friction laws (RSF laws) are empirical laws derived from laboratory experiments related to rock friction. They have been used to quantitatively describe complex fault friction processes. With a combination of the RSF laws and the McKenzie-Brune frictional heat generation model, we have studied the effects of frictional heating processs on the fault strength variation and temporal evolution of temperature based on the spring-slider-fault system subjected to Ruina and Chester-Higgs RSF laws. The system equations are solved efficiently by Dormand-Prince method with adaptive steps. First, with a comparison to the Ruina- model in which the temperature effect due to frictional heating on frictional strength is neglected, the numerical results show that the fault will be unstable slightly earlier for the Chester-Higgs- model in which the temperature effect due to frictional heating on frictional strength is taken into consideration, which indicates that the rise of temperature caused by frictional heating can lead to a slight time advance of fault instability. Second, by contrast with Ruina- model, the frictional strength will keep a little bit higher for the Chester-Higgs- model when the fault sliding at high speed, indicating that frictional heat can strengthen faults to a certain extent. Third, the simulation results also suggest that, at the same rupture velocity, the temperature change for the Chester-Higgs- model is much smaller than that given by the Ruina- model, indicating that frictional heat can also restrain the sharp rise of temperature on fault surface. In addition, under the same parameters and initial conditions, the seismic occurrence time giving by the Chester-Higgs- model is obviously shorter than that by the Ruina- model, indicating that a significant effect of friction heating generated on entire fault temporal evolution could greatly reduce the seismic recurrence time. Correspondingly, both static stress drop and total slip resulted from the Chester-Higgs- model is also smaller than that from the Ruina- model, respectively.</p>

Singularity Consideration in Numerical Solution of Contact Stress Problems

1982 ◽  
Vol 104 (3) ◽  
pp. 352-356 ◽  
Author(s):  
L. Nayak
Keyword(s):  
Numerical Methods ◽  
Numerical Solution ◽  
Contact Stress ◽  
Contact Area ◽  
Fundamental Equation ◽  
Elliptic Functions ◽  
Contact Problems ◽  
Hertzian Contact ◽  
Elastic Displacement ◽  
Proper Analysis

The paper gives an account of different approaches to deal with the weak singularity in numerical methods of contact stress problems when the methods are based on the fundamental equation relating the elastic displacement with pressure. Singularity consideration in a new method to simultaneously determine the shape of the contact area and the pressure distribution, particularly in non-Hertzian contact problems, has been dealt with using elliptic functions. Necessity of proper analysis of singularity is discussed and the final results when compared with Hertz solution have been shown to be satisfactory.

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