Effect Of Tangential Forces Research Articles

A Molecular Dynamics Study on the Adhesive Contact with Effect of Tangential Forces

A Molecular Dynamics Study on the Adhesive Contact with Effect of Tangential Forces

Prediction of Subsurface Microcrack Damage Depth Based on Surface Roughness in Diamond Wire Sawing of Monocrystalline Silicon.

In diamond wire saw cutting monocrystalline silicon (mono-Si), the material brittleness removal can cause microcrack damage in the subsurface of the as-sawn silicon wafer, which has a significant impact on the mechanical properties and subsequent processing steps of the wafers. In order to quickly and non-destructively obtain the subsurface microcrack damage depth (SSD) of as-sawn silicon wafers, this paper conducted research on the SSD prediction model for diamond wire saw cutting of mono-Si, and established the relationship between the SSD and the as-sawn surface roughness value (SR) by comprehensively considering the effect of tangential force and the influence of the elastic stress field and residual stress field below the abrasive on the propagation of median cracks. Furthermore, the theoretical relationship model between SR and SSD has been improved by adding a coefficient considering the influence of material ductile regime removal on SR values based on experiments sawing mono-Si along the (111) crystal plane, making the theoretical prediction value of SSD more accurate. The research results indicate that a decrease in wire speed and an increase in feed speed result in an increase in SR and SSD in silicon wafers. There is a non-linear increasing relationship between silicon wafer SSD and SR, with SSD = 21.179 Ra4/3. The larger the SR, the deeper the SSD, and the smaller the relative error of SSD between the theoretical predicted and experimental measurements. The research results provide a theoretical and experimental basis for predicting silicon wafer SSD in diamond wire sawing and optimizing the process.

Experimental investigation on the effect of contact forces on uneven longitudinal wear of rail material

The effect of contact forces on rail uneven longitudinal wear was investigated using three series of rolling tests, including tests with the same tangential force and varying normal force, tests with the same normal force and varying tangential force, and tests with varying tangential and normal forces. Results indicated that the effect of tangential force on rail uneven longitudinal wear was greater than that of normal force. When the tangential force was the same, rail uneven longitudinal wear occurred under the small normal force condition. As the normal force increased, the wear rate decreased. With the same normal force, rail uneven longitudinal wear occurred under the large tangential force condition. The main damage of the unevenly worn rail was oxidative wear and fatigue wear. The oxidative wear and ploughing were more severe at the crest. Plastic deformation, the degree of grain refinement and fatigue cracks were more severe at the trough. More severe fatigue cracks at the trough lead to more severe wear and then the aggravation of rail uneven longitudinal wear.

Numerical simulation of droplet coalescence based on the SPH method

In this paper, the smoothed particle hydrodynamics (SPH) method is employed in modeling and numerical simulation of droplet coalescence. Considering the effect of tangential force on boundary material, besides normal force, tangential force is also introduced in the continuum surface force (CSF) model. The formation of droplet, the coalescence processes of two droplets and three droplets are simulated by the modified CSF model. The validity of the modified model is verified from the aspects of the morphological change of the droplet, the smoothness of free surface and the conservation of the centroid of the system. Compared with finite element method, the results of the modified CSF model show that tangential force plays a crucial role in the CSF model when dealing with model boundary with curves and sharp angles.

A Stability Estimation Approach in Vehicle Planar Motion Considering Longitudinal Dynamics

A stability estimation approach is proposed to support complementary stability criterion design in vehicle planar motion. The comprehensive effect of tangential force and axle load transfer on tire cornering characteristics is considered corresponding to the longitudinal dynamics effects. The effectiveness of different stability concept is discussed in terms of the physical meaning of state variables in 3DOF differential systems. Based on the sense of technical stability, the 3DOF model is simplified according to longitudinal dynamics characteristic within definite observation time interval. The central equilibrium points continuum properties of the simplified model can be used to estimate the vehicle behavior in planar motion.

Mechanism of dent initiated flaking and bearing life enhancement technology under contaminated lubrication condition: Part I: Effect of tangential force on dent initiated flaking

In this paper, we have clarified experimentally the mechanism of dent initiated flaking as observed in rolling element bearings operating under contaminated lubrication conditions. A characteristic of dent initiated flaking is the initiation of cracks on the trailing edge of dents relative to the rolling direction. Based on the results of twin-disk testing and ball-on-rod rolling contact fatigue (RCF) testing conducted, we have confirmed that the crack initiation at the edge of a dent is strong influenced by the tangential force. The tangential force leads to the generation of a large tensile stress at the trailing edge of dents, which in turn leads to crack initiation.

Effect of tangential force on wear behaviour of steels in reciprocating rolling and rolling–sliding contact

A new rolling testing apparatus was developed on a tension–compression hydraulic machine with a high precision. The aim of this paper is to study the transition of wear mechanisms of steels with the increase of tangential friction force between contact surfaces in rolling. The wear modes were particularly analyzed during the passage from rolling to mixed rolling–sliding contact.

Effect of Coefficient of Friction on Rolling Contact Fatigue Properties in Structural Metals.

Two kinds of the as-received and the heat treated structural steel, the nickel chromium alloy and the copper alloy were selected for this investigation. The rolling contact fatigue tests with specific sliding 0, 3, 9, 20 and 30% were carried out measuring tangential force. The pulsating compression fatigue tests and the completely reversed torsion fatigue tests were carried out too. The effect of tangential force on the fatigue limit under the rolling contact fatigue were investigated. The relationships of the fatigue limit among the rolling contact fatigue, the pulsating compression fatigue and the completely reversed torsion fatigue were examined on the basis of the stress analyses under the contact surface. Then the fatigue limit ps under the rolling contact fatigue could be estimated from the tensile strength σB, the yield stress σB, Young's modulus E and the coefficient of friction μ as ps=0.07σB√(E/σy)(1-3μ).

Effect of Surface Roughness on Contact Pressure of Static Seals : Effect of Tangential Force on Conical Inside-Seal Surface

The sealing characteristics between a turned surface of soft material such as copper and a smooth seal surface of a rigid steel ball in static contact were investigated. This seal surface received not only a normal force but also a tangential force. The following results were obtained from calculations using a model that considered surface roughness on a turned seal surface as a wedge-shaped asperity, and gas leakage tests. ( 1 ) The linear sealing load Pc/l decreased with a decrease in the conical half-angle θ of the conical inside-seal surface. In the case of a surface roughness of 8 μm, the value of Pc/l at θ=15° was about 0.4 times that at θ=60°. ( 2 )The recommended values of θ were in the range of 5° to 35°, and the Pc/l values corresponding to this range were predicted.

Effect of Surface Roughness on Compressive Stress of Static Seals. 5th Report. Effect of Tangential Force on a Conical Inside Seal Face.

The sealing characteristics between a turned surface of soft material such as copper and a smooth seal face of a rigid steel ball in static contact were investigated. This seal face received not only normal force but also tangential force. The following results were obtained from calculations by using a model that considered a surface roughness on a turned seal face as a wedge-like projection, and gas leak tests. (1) The compressive force for sealing, Pc/l, decreased with a decrease in the conical half angle, θ of seal face. In the case of a surface roughness of 8 μm, the value of Pc/l at θ=15° was about 0.4 times that at θ=60°. (2) The recommended values of θ were in the range from 5° to 35°, and the Pc/l values corresponding to the range were able to be forecast.

The dynamics of tadpole and horseshoe orbits: II. The coorbital satellites of saturn

The recently discovered coorbital satellites of Saturn, 1980S1 and 1980S3, are shown to be librating in horseshoe orbits. By considering the effects of tangential forces on the semimajor axes of the satellite orbits, we derive an accurate relation between the sum of the satellite masses and (a) their minimum angular separation, (b) the variation of their angular separation with time and (c) the libration period. Observations of (b) and (c) are the most practical methods of determining the satellite masses. The orbits of the coorbital satellites of Dione and Tethys are discussed. We demonstrate the possibility of calculating a new value for the mass of Dione and we show that one of the coorbital satellites of Tethys could be moving in a horseshoe orbit even though another satellite is librating in a tadpole orbit about the leading Lagrangian equilibrium point L 4. The origin of coorbital satellites and the stability of their orbits are discussed.

The effect of tangential force on the contact of elastic solids in adhesion

This paper describes a study of adhesion between elastic solids and in particular the effect of a tangential force upon the size of the contact area. In the first part of the paper, the relation between the stress intensity factor of the normally loaded contact and the overall energy balance approach is discussed. In the second and main part of the paper, an analysis is given for the influence of a tangential force on the adhesive contact. The equation derived to describe its effect on the contact size has been verified by experiments carried out on rubber hemispheres pressed against a glass flat. The experimental results show qualitatively a clear reduction in contact area when a tangential force acts and quantitatively a reasonable agreement with theory within the limits of experimental error.

The Influence of Elastic Deformation upon the Motion of a Ball Rolling between Two Surfaces

When a ball rolls between two surfaces, in general, a tangential contact force and a relative angular velocity of spin are present at each point of contact. Both these actions give rise to tangential frictional tractions transmitted across the contact surface which are shown to result in a velocity of creep of the ball in a direction perpendicular to the nominal rolling path. The magnitude of the creep velocity depends critically upon the magnitudes of the tangential force and the velocity of spin. If these actions are small there is negligible slip between the contacting surfaces and the creep motion is predominantly a function of the elastic properties of the materials. At larger spin velocities slip extends over a greater proportion of the contact area and the creep is influenced by the frictional properties of the surfaces. Creep measurements have been made over a wide range of conditions of rolling. The results are reduced to non-dimensional form, in terms of two parameters expressing the effect of tangential forces and spin respectively. The resistance to rolling has been measured and is shown to control the axis about which the ball rolls. The detailed mechanism of the rolling process is discussed.

Contact of metallic bodies: Effect of tangential force : J. S. Courtney-Pratt and E. Eisner, Engineering, v. 185, Feb. 7, 1958, p. 182–183

Contact of metallic bodies: Effect of tangential force : J. S. Courtney-Pratt and E. Eisner, Engineering, v. 185, Feb. 7, 1958, p. 182–183