Dynamics of a Siped Tire Tread Block—Experiment and Simulation3

2009 ◽  
Vol 37 (4) ◽  
pp. 323-339 ◽  
Author(s):  
S. Ripka ◽  
G. Gäbel ◽  
M. Wangenheim
Keyword(s):  
Contact Zone ◽  
Surface Texture ◽  
Sliding Friction ◽  
Rolling Process ◽  
Contact Conditions ◽  
Normal Contact ◽  
Lubrication Film ◽  
Tangential Forces ◽  
Normal Contact Pressure ◽  
Contact Situation

Abstract Within the contact zone between tire and road all normal and tangential forces have to be transmitted. The tread block is the only tire component which is in direct contact to the pavement and therefore of special interest. The rolling process of a tire can be seen as a chronology of single contact events between tread block and road surface, whereas the contact situation in detail is usually unknown. The surface texture of the pavement comprises a large range of surface wavelengths which leads to a small area of real contact and to complex contact conditions. Under braking and acceleration procedures sliding friction occurs within the footprint especially at the trailing area of the contact zone. The tangential forces strongly depend on the contact conditions, e.g., surface texture, sliding velocity, normal contact pressure, temperature, tread block geometry, and existence of a lubrication film. An intermediate layer not only simply lowers the friction coefficient but also the whole contact situation changes. This effect is considerably existent for siped tire tread blocks which react in a different manner compared to nonsiped tread blocks. Within this publication the dynamics of siped tread blocks in contact are analyzed and a mechanical model will be presented to explain the observed phenomena. The simulation results are verified by experiments.

scholarly journals Micromechanism of the Breakage of Two Spherical Gypsum Particles under Normal–Tangential Contact Conditions

2021 ◽  
Vol 11 (9) ◽  
pp. 4039
Author(s):  
Yiran Niu ◽  
Lin Li ◽  
Yanwei Zhang ◽  
Shicai Yu ◽  
Jian Zhou
Keyword(s):  
Tangential Force ◽  
Coarse Grained ◽  
Spherical Particles ◽  
Contact Conditions ◽  
Normal Contact ◽  
Tangential Contact ◽  
Theoretical Predictions ◽  
Tangential Forces ◽  
Predicted Values ◽  
The Relationship

Contact breakage of particles makes a large difference in the strength of coarse-grained soils, and exploring the characteristics within the process of the breakage is of great significance. Ignoring the influence of particle shape, the micromechanism of two spherical particles breaking under normal–tangential contact conditions was investigated theoretically and experimentally. Through theoretical analysis, the breakage form, the shape and size of the conical core, and the relationship between the normal and tangential forces at crushing were predicted. Particle contact tests of two gypsum spheres were carried out, in which the breakage forms, features of the conical cores and the normal and tangential forces at crushing were recorded for comparison with the predicted values. The test results and the theoretical predictions showed good agreement. Both the analysis and test demonstrate that the presence of tangential forces causes the conical core to assume the shape of an oblique cone, and the breakage form to change. Moreover, with increasing normal contact force, the tangential force needed for crushing increases gradually first and then decreases suddenly.

Parameter Study of Offset Press Cylinder Based on Sliding Friction

2010 ◽  
Vol 174 ◽  
pp. 299-302 ◽  
Author(s):  
Hai Yan Zhang ◽  
He Ping Hou ◽  
Jun Feng Si ◽  
Xiao Yu Chen
Keyword(s):  
Contact Area ◽  
Sliding Friction ◽  
Accurate Determination ◽  
Rolling Process ◽  
Elastic Cylinder ◽  
Parameter Study ◽  
Cylinder Radius ◽  
Printing Quality ◽  
Dot Gain

In the contact area of offset, a relative slide occurs between the surface of plate cylinder and blanket cylinder, which changes the print image and influences the printing quality. The relative slide in the cylinders’ rolling process is investigated, and the determination rule of cylinders’ geometric parameters of offset press is proposed. The results show that the relative slide is minimization under the condition that the compression of elastic cylinder radius is 0.2 times bigger than that of rigid cylinder radius, and the deformation of print image and dot gain both are minimization. The results provide theoretical direction for accurate determination of cylinder radius of offset press.

scholarly journals Investigation on Electrically-Assisted Rolling Process of Surface Texture for Drag Reduction

2021 ◽  
Vol 1024 (1) ◽  
pp. 012016
Author(s):  
Zhenhai Xu ◽  
Shaoxi Xue ◽  
Chunju Wang ◽  
Baosheng Liu ◽  
Debin Shan ◽  
...  
Keyword(s):  
Drag Reduction ◽  
Surface Texture ◽  
Rolling Process ◽  
Electrically Assisted

scholarly journals The Effect of Multilayer Architecture and Ta Alloying on the Mechanical Performance of Ti-Al-N Coatings under Scratching and Uniaxial Tension

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1307
Author(s):  
Artur Rubinovich Shugurov ◽  
Evgenii Dmitrievich Kuzminov
Keyword(s):  
Uniaxial Tension ◽  
Mechanical Performance ◽  
Multilayer Coating ◽  
High Hardness ◽  
Scratch Testing ◽  
Normal Contact ◽  
Multilayer Architecture ◽  
Normal Contact Pressure ◽  
Steel Substrates ◽  
Metal Layers

The present work is focused on a comparative study of the effect of Ti-Al interlayers and Ta alloying on the mechanical behavior of Ti1−xAlxN coatings under normal contact pressure and in-plane straining. The contact loading of the samples was carried out by scratch testing, while the in-plane tensile straining was performed by uniaxial tension of the coated steel substrates. The Ti0.45Al0.55N and Ti0.43Al0.45Ta0.12N monolithic coatings as well as the Ti0.45Al0.55N/Ti0.45Al0.55 multilayer coatings with different number and thickness of the layers were deposited by DC magnetron sputtering. It was found that the introduction of the ductile Ti0.45Al0.55 layers into the Ti0.45Al0.55N coating and alloying with Ta led to their significant toughening. The improved toughness of the Ti0.43Al0.45Ta0.12N coating coupled with high residual compressive stress and high hardness resulted in its strongest resistance to cracking under scratching and tensile straining among the coatings studied. The multilayer coating with the thickest metal layers exhibited the improved resistance to delamination under in-plane straining.

scholarly journals New Numerical Solution of von Karman Equation of Lengthwise Rolling

2015 ◽  
Vol 2015 ◽  
pp. 1-20 ◽  
Author(s):  
Rudolf Pernis ◽  
Tibor Kvackaj
Keyword(s):  
Contact Stress ◽  
Rolling Force ◽  
Rolling Process ◽  
Normal Contact Stress ◽  
Normal Contact ◽  
Circular Arch ◽  
Relative Stress ◽  
Roll Flattening ◽  
Polygonal Curve ◽  
Rolling Torque

The calculation of average material contact pressure to rolls base on mathematical theory of rolling process given by Karman equation was solved by many authors. The solutions reported by authors are used simplifications for solution of Karman equation. The simplifications are based on two cases for approximation of the circular arch: (a) by polygonal curve and (b) by parabola. The contribution of the present paper for solution of two-dimensional differential equation of rolling is based on description of the circular arch by equation of a circle. The new term relative stress as nondimensional variable was defined. The result from derived mathematical models can be calculated following variables: normal contact stress distribution, front and back tensions, angle of neutral point, coefficient of the arm of rolling force, rolling force, and rolling torque during rolling process. Laboratory cold rolled experiment of CuZn30 brass material was performed. Work hardening during brass processing was calculated. Comparison of theoretical values of normal contact stress with values of normal contact stress obtained from cold rolling experiment was performed. The calculations were not concluded with roll flattening.

The Effect of a Tangential Contact Force Upon the Rolling Motion of an Elastic Sphere on a Plane

1958 ◽  
Vol 25 (3) ◽  
pp. 339-346
Author(s):  
K. L. Johnson
Keyword(s):  
Tangential Force ◽  
Elastic Plane ◽  
Rolling Motion ◽  
Elastic Sphere ◽  
Normal Contact ◽  
Ball Rolling ◽  
Slip Region ◽  
Flat Steel ◽  
Normal Contact Pressure ◽  
Theoretical Results

Abstract The motion and deformation of an elastic sphere rolling on an elastic plane under a normal contact pressure N have been studied for the case where a tangential force T is also sustained at the point of contact. Provided that T < μN (μ = coefficient of friction), the sphere rolls without sliding but exhibits a small velocity relative to the plane, termed “creep.” Following the work of Mindlin and Poritsky, it is shown that creep arises from slip over part of the area of contact, and further, that this slip takes place toward the trailing edge of the contact area. On the assumption of a locked region in which no slip occurs, of circular shape, tangential to the circle of contact at its leading point, surface tractions are found which satisfy the condition of no slip within the locked region and are approximately consistent with the laws of friction in the slip region. The variation of creep velocity with tangential force is thereby determined. Experimental measurements of the creep of a steel ball rolling on a flat steel surface are in reasonable agreement with the theoretical results.

Through a Black Hole into Parallel Universes

2020 ◽  
Vol 26 (2) ◽  
pp. 413-424
Author(s):  
Heinrich Härke
Keyword(s):  
Contact Zone ◽  
Cultural Exchange ◽  
Social Changes ◽  
British Isles ◽  
Anglo Saxon ◽  
Internal Contact ◽  
Cultural Boundary ◽  
Parallel Universes ◽  
Contact Situation ◽  
Settlement Areas

Abstract The Anglo-Saxon immigration of the 5th-6th centuries AD led to a dual contact situation in the British Isles: with the native inhabitants of the settlement areas in south-eastern England (internal contact zone), and with the Celtic polities outside the Anglo-Saxon areas (external contact zone). In the internal contact zone, social and ethnogenetic processes resulted in a complete acculturation of the natives by the 9th century. By contrast, the external contact zone between Anglo-Saxon and Celtic polities resulted in a cultural and linguistic split right across the British Isles up to the 7th century, and arguably well beyond. The cultural boundary between these two domains became permeable in the 7th century as a consequence of Anglo-Saxon Christianization which created a northern communication zone characterized by a distinct art style (Insular Art). In the early medieval British Isles, contact resulting from migration did not lead to cultural exchange for about two centuries, and it took profound ideological and social changes to establish a basis for communication.

Report Paper 3: Elastohydrodynamic Lubrication of ‘O’ Ring Seals

1969 ◽  
Vol 184 (12) ◽  
pp. 197-200
Author(s):  
I. A. Gibson ◽  
C. J. Hooke ◽  
J. P. O'Donoghue
Keyword(s):  
Theoretical Analysis ◽  
Film Thickness ◽  
Pressure Gradient ◽  
Contact Zone ◽  
Elastohydrodynamic Lubrication ◽  
Iterative Solution ◽  
Contact Conditions ◽  
Dry Contact

This report gives details of a theoretical analysis of the lubrication of ‘O’ ring seals. Under dry contact conditions the pressure gradient at inlet to the contact zone is infinite, and an iterative solution has been developed to determine the inlet sweep of pressure under conditions of elastohydrodynamic lubrication. The exit film thickness and pressures have also been determined for conditions of variable outlet viscosity and pressure gradient. Typical results for an ‘O’ ring are given for a standard seal section.

Contact Stiffness Parameters for Finite Element Modeling of Contact

2019 ◽  
Vol 799 ◽  
pp. 211-216
Author(s):  
Alina Sivitski ◽  
Priit Põdra
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Contact Stiffness ◽  
Influential Factors ◽  
Element Analysis ◽  
Normal Contact ◽  
Element Modeling ◽  
Contact Models ◽  
Machine Elements ◽  
Normal Contact Pressure

Contact modeling could be widely used for different machine elements normal contact pressure calculations and wear simulations. However, classical contact models as for example Hertz contact models have many assumptions (contact bodies are elastic, the contact between bodies is ellipse-shaped, contact is frictionless and non-conforming). In conditions, when analytical calculations cannot be performed and experimental research is economically inexpedient, numerical methods have been applied for solving such engineering tasks. Contact stiffness parameters appear to be one of the most influential factors during finite element modeling of contact. Contact stiffness factors are usually selected according to finite element analysis software recommendations. More precise analysis of contact stiffness parameters is often required for finite element modeling of contact.

Vacuum tribological properties of a composite Mo–MoS2film after atomic oxygen exposure irradiation

2019 ◽  
Vol 233 (8) ◽  
pp. 1236-1244
Author(s):  
Guo-zheng Ma ◽  
Peng-fei He ◽  
Yi-wen Wang ◽  
Shu-ying Chen ◽  
Ming Liu ◽  
...  
Keyword(s):  
Tribological Properties ◽  
Photoelectron Spectroscopy ◽  
Atomic Oxygen ◽  
Sliding Friction ◽  
Film Surface ◽  
Superficial Layer ◽  
Solid Lubrication ◽  
X Ray ◽  
Nanomechanical Properties ◽  
Lubrication Film

A composite Mo–MoS2solid-lubrication film measuring approximately 2-µm thick was prepared using a two-step composite process involving magnetron sputtering of Mo film followed by low-temperature ion sulfurization. Microstructure of the said film was characterized using scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Auger electron spectroscopy, and X-ray photoelectron spectroscopy, and nanomechanical properties of the Mo and Mo–MoS2film were tested using a nanoindenter. The Mo–MoS2film and GCr15 substrate were irradiated by atomic oxygen with the self-developed MSTS-1 space tribometer system equipped with an atomic oxygen beam at a flux of 9 × 1019atoms/cm2. Subsequently, vacuum tribological properties of the said substrate and film were examined and compared. Results demonstrated that the Mo film possessed a smooth and dense structure with stable nanomechanical properties. Part of the elemental Mo translated into MoS2post sulfurizing, thereby forming the Mo–MoS2composite film with an alternating soft and hard structure. The Mo–MoS2film demonstrated a low and stable friction coefficient of approximately 0.15 along with only a slight wear in vacuum. The film surface could be oxidized and eroded when exposed to the highly active and energetic atomic oxygen. Post atomic oxygen erosion, the film thickness demonstrated a decrease, and small amounts of MoO3were observed on the surface. However, all structural and property changes were limited to the superficial layer. The excellent tribological performance of the film could be restored when the surface layer was removed after a certain period of sliding friction.

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