Influence Of Tangential Force Research Articles

INFLUENCE OF TANGENTIAL SLIDING ON THE CONTACT AREA OF A MACROSCOPIC ADHESIVE CONTACT

Influence of tangential force on the adhesive contact, in particular on the adhesive strength and the contact area have been a subject of investigation and discussions for many years. Depending on the system under consideration, both increase and decrease of adhesion strength due to shearing of an adhesive contact have been reported. The same is valid for change of the contact area. While it is generally accepted that the contact area decreases when applying tangential traction, also opposite behaviour is possible. In the present paper we study theoretically and experimentally the conditions under which the contact area may increase or decrease due to shear.

The angular deformation of the ring with reference to the centrifugal forces

In the paper the boundary plane elasticity problem for the ring is solved usingMuskhelishvili complex potentialsmethod. The ring rotates uniformly under the influence of tangential forces, and the centrifugal forces of inertia are taken into account. Themutual rotation angle of the boundary points is obtained by analyzing the displacement field.

Squat growth—Some observations and the validation of numerical predictions

Abstract This paper presents evidences obtained by field monitoring, measurement and survey to show the validity of some numerical predictions about squat growth. The predictions concerns a postulated squat growth process, the relationship between the dynamic contact force and the corrugation-like wave pattern that often follows squats, the high frequency wheel–rail interaction related to squats, and the influence of tangential force on squat growth. The observations reveal signature tunes of squats which may be used for early detection of squats, show the necessity to include high frequency dynamic wheel–rail interaction in squat-related analyses, and provide evidence of relationship between rolling stock performance and squat initiation and growth. In validating the numerical results the model is also verified for its applicability to analyses of squat-related problem and other problems similar in nature. The model can be employed for the solution of three-dimensional frictional rolling contact problems. It can also be used for analyses of loading conditions of wheel–rail contact at short wave defects, and the associated damages such as wear, plastic deformation, fatigue and corrugation.

Surface durability of powder-forged roller treated by shot peening

To investigate the influence of shot peening on the surface durability of powder-forged rollers, the case-hardened powder-forged rollers with a forging density of 7.5 g/cm3 treated by the single shot peening and the double shot peening were fatigue-tested under a sliding-rolling contact condition. The surface roughness, the surface hardness and the surface compressive residual stress of the rollers were increased by the shot peening. In addition, the pores near the roller surface were deformed by the shot peening. The failure mode of all the test rollers was spalling due to subsurface cracking. The fatigue lives of all the test rollers were improved by the shot peening, and that of the test roller S08, which was shot-peened with the hardest steel shots in this experimental range, was especially improved. The surface durability of the test roller S08 was also most improved by the shot peening. Cracks became difficult to occur and propagate under the roller surface since the pores near the roller surface were deformed by the stronger shot peening. In this study, double shot peening, which generally restrains the increase in surface roughness, was not particularly effective for the improvement in the surface durability of the powder-forged rollers, because the influence of tangential force on fatigue was not always great in a case of subsurface cracking.

Experimental analysis of wheel/workpiece dynamic interactions in grinding

The aim of this work is to study the wheel/workpiece dynamic interactions in high-speed grinding using vitrified CBN wheel and DTG (difficult to grind) work materials. This problem is typical in the grinding of engine valve heads. The influence of tangential force per abrasive grain was investigated as an important control variable for the determination of G ratio. Experiments were carried out to observe the influence of vibrations in the wheel wear. The measurements of acoustic emission (AE) and vibration signals helped in identifying the correlation between the dynamic interactions (produced by forced random excitation) and the wheel wear. The wheel regenerative chatter phenomenon was observed by using the wheel mapping technique.

Rolling Contact of a Cylinder with Wavy Surface

We consider the case of two-dimensional elastic rolling contact of wavy surfaces. It is assumed that the normal stresses do not affect the horizontal displacements and the vertical displacements are independent of the tangential stresses. This assumption makes it possible to consider the problems of normal and tangential contact separately. Both problems are nonlinear and solved by using specially constructed iterative procedures. The influence of tangential forces and the parameters of waviness on the modes of sticking and sliding in some contact zones is studied and reflected in the plots.