Elastic-Plastic Partial Slip Rolling Wheel-Rail Contact With an Oblique Rail Crack

2004 ◽  
Author(s):  
Yung-Chuan Chen ◽  
Jao-Hwa Kuang
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Friction Force ◽  
Element Model ◽  
Partial Slip ◽  
Contact Pressure Distribution ◽  
Tractive Force ◽  
Plastic Energy ◽  
Elastic Plastic ◽  
Pressure Distributions

The effect of rail surface crack on the wheel-rail contact pressure distribution under partial slip rolling was studied in this work. The elastic-plastic finite element model was employed for stress analyses. The numerical simulations were used to explore the effects of the contact distances and tractive force on the normal and tangential contact pressure distributions, tip plastic energy and critical wheel applied load. Contact elements were used to simulate the interaction between wheel and rail and crack surfaces. Numerical results indicate that the contact pressure distributions are significantly affected by the rail crack. Traditional contact theories are not available to describe the contact pressure distribution on the contact crack surfaces. Results also indicate that a higher friction force on the contact crack surfaces is observed for wheel subjected a larger tractive force. A larger crack surfaces friction force can reduce the sliding between crack surfaces and leads to a smaller tip plastic energy.

Elastic-Plastic Partial Slip Rolling Wheel-Rail Contact with an Oblique Rail Crack

2005 ◽  
Vol 127 (4) ◽  
pp. 705-712 ◽  
Author(s):  
Yung-Chuan Chen ◽  
Jao-Hwa Kuang
Keyword(s):  
Friction Force ◽  
Contact Stress ◽  
Surface Friction ◽  
Element Model ◽  
Partial Slip ◽  
Stress Distributions ◽  
Tractive Force ◽  
Plastic Energy ◽  
Elastic Plastic ◽  
Contact Distance

This study employs an elastic-plastic finite element model to investigate the effect of oblique rail surface crack on the wheel-rail contact stress distribution under partial slip rolling conditions. Numerical simulations are performed to explore the effects of the contact distance and tractive force on the contact pressure and tangential stress distributions, tip plastic energy, and critical wheel applied load. Contact elements are used to simulate the interaction between the surfaces of the wheel rail and the crack. The numerical results indicate that the contact stress distributions are influenced significantly by the presence of oblique cracks in the rail. The results also indicate that a higher friction force is induced on the crack surfaces when a greater tractive force is applied to the wheel. This increased crack surface friction force reduces the sliding between the crack surfaces and hence causes a reduction in the tip plastic energy.

scholarly journals A Three-Dimensional Semianalytical Model for Elastic-Plastic Sliding Contacts

2007 ◽  
Vol 129 (4) ◽  
pp. 761-771 ◽  
Author(s):  
Daniel Nélias ◽  
Eduard Antaluca ◽  
Vincent Boucly ◽  
Spiridon Cretu
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Computing Time ◽  
Three Dimensional ◽  
Gradient Methods ◽  
Reciprocal Theorem ◽  
Contact Pressure Distribution ◽  
Sliding Contacts ◽  
Elastic Plastic ◽  
Residual Strains

A three-dimensional numerical model based on a semianalytical method in the framework of small strains and small displacements is presented for solving an elastic-plastic contact with surface traction. A Coulomb’s law is assumed for the friction, as commonly used for sliding contacts. The effects of the contact pressure distribution and residual strain on the geometry of the contacting surfaces are derived from Betti’s reciprocal theorem with initial strain. The main advantage of this approach over the classical finite element method (FEM) is the computing time, which is reduced by several orders of magnitude. The contact problem, which is one of the most time-consuming procedures in the elastic-plastic algorithm, is obtained using a method based on the variational principle and accelerated by means of the discrete convolution fast Fourier transform (FFT) and conjugate gradient methods. The FFT technique is also involved in the calculation of internal strains and stresses. A return-mapping algorithm with an elastic predictor∕plastic corrector scheme and a von Mises criterion is used in the plasticity loop. The model is first validated by comparison with results obtained by the FEM. The effect of the friction coefficient on the contact pressure distribution, subsurface stress field, and residual strains is also presented and discussed.

Analysis on the Contact Pressure Distribution of Chemical Mechanical Polishing by the Bionic Polishing Pad with Phyllotactic Pattern

2011 ◽  
Vol 215 ◽  
pp. 217-222 ◽  
Author(s):  
Y.S. Lv ◽  
Nan Li ◽  
Jun Wang ◽  
Tian Zhang ◽  
Min Duan ◽  
...  
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Chemical Mechanical Polishing ◽  
Mechanical Polishing ◽  
Wafer Surface ◽  
Boundary Edge ◽  
Contact Pressure Distribution ◽  
Element Analysis ◽  
Pressure Distributions ◽  
Polishing Pad

In order to make the contact pressure distribution of polishing wafer surface more uniform during chemical mechanical polishing (CMP), a kind of the bionic polishing pad with sunflower seed pattern has been designed based on phyllotaxis theory, and the contact model and boundary condition of CMP have been established. Using finite element analysis, the contact pressure distributions between the polishing pad and wafer have been obtained when polishing silicon wafer and the effects of the phyllotactic parameter of polishing pad on the contact pressure distribution are found. The results show that the uniformity of the contact pressure distribution can be improved and the singularity of the contact pressure in the boundary edge of polished wafer can be decreased when the reasonable phyllotactic parameters are selected.

Hot judder behavior in multidisc clutches

2016 ◽  
Vol 231 (1) ◽  
pp. 136-146 ◽  
Author(s):  
Biao Ma ◽  
Likun Yang ◽  
Heyan Li ◽  
Nan Lan
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Degrees Of Freedom ◽  
Frictional Heat ◽  
Contact Pressure Distribution ◽  
Element Analysis ◽  
Pressure Distributions ◽  
Engagement Process ◽  
The Coefficient Of Friction ◽  
Interface Contact

This paper presents an investigation of the hot judder phenomenon of multidisc clutches, which takes place during the engagement process. Depending on the results of finite element analysis, a pressure distribution function is defined and a contact pressure equation is established to demonstrate the non-uniformity of the contact pressure distribution on the friction interfaces due to frictional heat. The relationship between the coefficient of friction and the temperature is analyzed. A 4 degrees of freedom power-train model is developed to evaluate the clutch judder behavior. The paper indicates that the clutch judder is influenced by the non-uniformity of the interface contact pressure distribution, which is excited by frictionally induced thermal load. The non-uniform contact pressure distributions along the radial direction have a slight influence on the clutch judder, while the uneven contact pressure distributions along the circumference contribute to the judder substantially. Furthermore, the results in this work can be used to study the operation instability and the thermal failure of clutches.

scholarly journals Effects of tire – pavement contact pressure distributions on the response of asphalt concrete pavements

1995 ◽  
Vol 22 (5) ◽  
pp. 849-860 ◽  
Author(s):  
Zhong Qi Yue ◽  
Otto J. Svec
Keyword(s):  
Pressure Distribution ◽  
Numerical Integration ◽  
Contact Pressure ◽  
Asphalt Concrete ◽  
Point Load ◽  
Asphalt Pavements ◽  
Numerical Verification ◽  
Concrete Pavements ◽  
Contact Pressure Distribution ◽  
Pressure Distributions

The paper presents the development of a computer program VIEM for the elastic analysis of multilayered elastic pavements under the action of arbitrary tire–pavement contact pressure distributions. The techniques adapted in VIEM primarily involves the use of a two-dimensional numerical integration to integrate point load solutions over the distributed pressure after discretizing the contact area into a finite number of triangular or quadrilateral elements. Values of contact pressure are inputted at the node points of discretized area. Numerical verification of VIEM indicates that numerical solution of high accuracy can be efficiently calculated for the elastic response of multilayered asphalt pavements. As a result, the determination of displacements and stresses (strains) can be achieved using a personal computer. With the use of VIEM, a theoretical investigation is further performed to illustrate the effects of tire–pavement contact pressure distributions on the response of asphalt concrete pavements. An in situ measured tire–pavement contact pressure distribution is utilized in the investigation. The response of asphalt concrete pavements due to the action of this measured contact pressure distribution is examined and compared with that due to the action of a uniform and circular contact pressure distribution by taking into account the influences of moduli and thicknesses of structural layers. The results of this investigation confirm theoretically a general consensus that details of the contact pressure distribution affect stresses and strains near the surface of the pavement, whereas the response in the lower layers depends mainly on the overall load. In particular, the contact pressure distributions have a significant effect on the horizontal tensile strains at the bottom of thin asphalt concrete layer which control the fatigue failure of asphalt pavements. Key words: tire–pavevment interaction, three-dimensional stress analysis, asphalt concrete pavements, numerical integration, multilayered elastic solids, point load solution.

scholarly journals Research on Contact Pressure Distribution of Pad

2018 ◽  
Vol 198 ◽  
pp. 01002
Author(s):  
Dong Chen ◽  
Guofeng Zou
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Working Condition ◽  
Great Influence ◽  
Element Model ◽  
Disc Brake ◽  
Contact Pressure Distribution ◽  
Structural Coupling ◽  
Emergency Braking ◽  
Force Characteristics

A simplified thermo-structural coupling finite element model of disc brake was developed. The contact pressure distribution of new pad was simulated under an emergency braking condition. The result shows that the contact pressure distribution of pad is not uniform when the new pad is in normal working condition. The inhomogeneity of the contact pressure is a critical cause of tangential partial wear. Compared the contact pressure distribution of new pad, uniform wear pad and tangential partial wear pad, the influence of wear amount and tangential partial wear on the contact pressure of pad was investigated. The results prove that the influence of wear amount on the contact pressure of pad is very small, while tangential partial wear has a great influence on the contact pressure of pad. The wear and force characteristics of pad are analyzed. The wear of its life cycle of pad is obtained, and the reliability and accuracy of the simulation are verified.

Two-Dimensional Contact Pressure Distribution of a Radial Tire

1990 ◽  
Vol 18 (2) ◽  
pp. 80-103 ◽  
Author(s):  
T. Akasaka ◽  
M. Katoh ◽  
S. Nihei ◽  
M. Hiraiwa
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Side Wall ◽  
Bending Moment ◽  
Two Dimensional ◽  
Contact Pressure Distribution ◽  
Friction Forces ◽  
Radial Tire ◽  
Pressure Distributions ◽  
Reaction Forces

Abstract Two-dimensional contact pressure distribution of a radial tire, statically compressed to a flat roadway, is analyzed using a rectangular contact patch. The tire structure is modeled by a spring-bedded ring belt comprised of a laminated-biased composite strip. The belt is supported by radial springs simulating the sidewall. The spring constant Kr was well defined previously by one of the authors. Deformation of the rectangular flat belt is obtained theoretically. The belt is subjected to inflation pressure, reaction forces transmitted from the spring bed of the tread rubber, and shearing force and bending moment along the belt boundaries brought from side-wall springs and the detached part of the ring belt. In-plane membrane forces, which are not uniform in the contact area, due to the friction forces acting between the tread surface and the roadway are also applied. The resulting contact pressure distributions in the circumferential direction are shown to be convex along the shoulder, but concave along the crown center line. This distribution agrees well with the experimental results.

Modeling of contact pressure distribution and friction limit surfaces for soft fingers in robotic grasping

Robotica ◽  
2014 ◽  
Vol 32 (7) ◽  
pp. 1005-1015 ◽  
Author(s):  
Sadeq Hussein Bakhy
Keyword(s):  
Pressure Distribution ◽  
Contact Mechanics ◽  
Contact Pressure ◽  
Friction Force ◽  
Pressure Profile ◽  
Humanoid Robots ◽  
Limit Surface ◽  
Contact Pressure Distribution ◽  
Mechanics Model ◽  
Friction Limit Surface

SUMMARYA new theory in contact pressure distribution and friction limit surfaces for modeling of hemicylindrical soft fingertips is introduced, to define the relationship between friction force and the moment with respect to the normal axis of contact. A general pressure-distribution function is proposed to capture material properties and contact geometry with various pressure profiles, and the coefficient of pressure distribution over the rectangular contact area is found between π and π/2. Combining the results of the contact mechanics model with the contact pressure distribution, the normalized friction limit surface can be derived for anthropomorphic soft fingers. The numerical friction limit surface of hemicylindrical soft-finger contact can be approximated by an ellipse, with the major and minor axes as the maximum friction force and the maximum moment with respect to the normal axis of contact, respectively. The results show that the friction limit surfaces are improved (13%–17%), if hemicylindrical fingertips are used rather than hemispherical fingertips at the same radius of fingertip, shape factor of the pressure profile, and applied load. Furthermore, the results of the contact mechanics model and the pressure distribution for soft fingers facilitate the construction of numerical friction limit surfaces, enabling to analyze and simulate the contact behaviors of grasping and manipulation in humanoid robots, prosthetic hands, and robotic hands.

A New Prediction Methodology For Dynamic Contact Pressure Distribution In A Disc Brake

2012 ◽  
Author(s):  
Abd Rahim Abu Bakar ◽  
Mohd Kameil Abdul Hamid ◽  
Huajiang Ouyang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Pressure Distribution ◽  
Surface Topography ◽  
Contact Pressure ◽  
Dynamic Contact ◽  
Element Model ◽  
Disc Brake ◽  
Contact Pressure Distribution ◽  
Static Contact

Taburan tekanan sentuhan dinamik masih lagi tidak dapat diukur secara uji kaji. Ini menjadikan kaedah berangka melalui analisis unsur terhingga merupakan pilihan alternatif yang terbaik bagi tujuan tersebut. Namun begitu, model unsur terhingga yang dibina perlu terlebih dahulu diujisahkan agar hasil ramalan yang diperolehi memuaskan dan realistik. Kertas kerja ini mencadangkan dan menjalankan pengujisahan ke atas model secara tiga peringkat iaitu mengujisahkan aspek kelakuan dinamik pada setiap komponen brek cakera dan juga pemasangan selain daripada pengujisahan tekanan sentuhan statik dengan keputusan daripada pengujian. Model 3-dimensi telah dibina berdasarkan komponen sebenar. Permukaan topografi bahan geseran diambilkira dan dimodelkan dalam model unsur terhingga. Hasil analisis mencatatkan keputusan yang memberangsangkan di mana model menunjukkan persamaan dengan keputusan uji kaji bagi kelakukan dinamik dan juga tekanan sentuhan statik. Setelah model diujisahkan, analisis tekanan sentuhan dinamik dilakukan. Kata kunci: brek cakera, tekanan sentuhan dinamik, topografi permukaan, ujian sentuhan, analisis modal, unsur terhingga The dynamic contact pressure distribution in a disc brake system remains impossible to measure through experimental methods. This makes numerical analysis using the finite element method an indispensable alternative tool to its prediction. However, the finite element model must first be validated through appropriate analyses so that realistic predicted results can be obtained. This paper proposes and carries out a three-stage validation methodology: validating the dynamic aspect of each brake component and the brake assembly using modal testing data and the contact aspect using the experimental results of static contact pressure. A detailed 3-dimensional finite element model of an actual disc brake was developed. Brake pad surface topography is also taken into consideration. Good agreement is achieved between predicted and experimental results both in modal analysis and static contact pressure distributions. Once a validated model was obtained, contact analysis for dynamic condition of the disc brake is performed. Key words: disc brake, dynamic contact pressure, surface topography, contact tests, modal analysis, finite element

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