scholarly journals Influence of Rock Properties on Wear of M and SR Grade Rubber with Varying Normal Load and Sliding Speed

2017 ◽  
Vol 62 (3) ◽  
pp. 1787-1793 ◽  
Author(s):  
Samir Kumar Pal ◽  
K.U.M. Rao ◽  
P. Sathish Kumar ◽  
R. Rajasekar
Keyword(s):  
Surface Roughness ◽  
Shear Strength ◽  
Normal Load ◽  
Operating Conditions ◽  
Rock Properties ◽  
Sliding Speed ◽  
Lower Load ◽  
Conveyor Belts ◽  
Material Transportation ◽  
Set Up

AbstractRubbers are interesting materials and are extensively used in many mining industries for material transportation. Wear of rubber is a very complex phenomenon to understand. The present study aims to explain the influence of rock properties on wear of M and SR grade rubber used in top cover of conveyor belts. Extensive laboratory experiments were conducted under four combinations of normal load and sliding speed. The wear of both the rubber types were analyzed based on the rock properties like shear strength, abrasivity index and fractal dimension. A fully instrumented testing set up was used to study the wear of rubber samples under different operating conditions. In general, wear was higher for M grade rubber compared to SR grade rubber. Increase in shear strength of rocks depicts decreasing trend for the wear of M and SR grade rubber at lower load conditions. Moreover, a higher load combination displays no definite trend in both the rubbers. The strong correlation between the wear of rubber and frictional power for all rubber-rock combinations has given rise to the parameter A, which reflects the relative compatibility between the rubber and rock. Increase of Cerchar’s Abrasivity Index of rocks shows gradual enhancement in wear for M grade rubber in all the load and speed combinations whereas, it fails in SR grade rubber due to its higher strength. The wear of rubber tends to decrease marginally with the surface roughness of rocks at highest normal load and sliding speed in M grade rubber. However, the wear of M and SR grade rubber is influenced by the surface roughness of rocks.

An Experimental Study of Some of the Factors Affecting the Contact Conditions and the Slip between a Rolling Ball and Its Track

1967 ◽  
Vol 182 (1) ◽  
pp. 757-768 ◽  
Author(s):  
J. Hailing ◽  
M. A. Al-Qishtaini
Keyword(s):  
Experimental Study ◽  
Surface Roughness ◽  
Wear Debris ◽  
Normal Load ◽  
Operating Conditions ◽  
Hydrodynamic Effect ◽  
Contact Conditions ◽  
Factors Affecting ◽  
Rolling Ball ◽  
Theoretical Considerations

The problem of a rolling ball subjected to combined normal load and tangential tractions has been studied for a variety of operating conditions. It is shown that for dry steady state loading the resultant slip may be explained in terms of a microslip theory based on the differential elastic straining of the ball and the track. Such results necessitate a careful experimental technique in which the surfaces must be free from contamination and loose wear debris. It is also shown that the preceding arguments are not significantly affected by dynamically varying loads or by speed variations in the range 0-150 in/min. The slip behaviour is found to be markedly affected by the presence of a lubricant. The behaviour with load and speed now indicates a definite hydrodynamic effect, although the theoretical film thickness is considerably less than the surface roughness. These results agree well with the results of other investigations for similar conditions. Using these experimental results and theoretical considerations a tentative power law formulation for the slip under such conditions is proposed.

Influence of Surface Roughness on Traction and Scuffing Performance of Lubricated Contacts for Aerospace and Automotive Gearing

2012 ◽  
Author(s):  
Sam Shon ◽  
Ahmet Kahraman ◽  
Kelsen LaBerge ◽  
Brian Dykas ◽  
David Stringer
Keyword(s):  
Surface Roughness ◽  
Operating Conditions ◽  
Test Set ◽  
Lubricated Contacts ◽  
Gear Steel ◽  
Steel Aisi ◽  
Set Up ◽  
The Impact ◽  
Disk Test

In this study, a two-disk test set-up was employed to investigate the impact of surface roughness on the performance of lubricated contacts. In an attempt to simulate contacts from automotive transmissions and rotorcraft gearboxes, roller specimens made of a typical automotive gear steel (AISI 5120) and a common rotorcraft gear steel (AISI 9310) were paired with 80W90 and MIL-PRF23699 lubricants, respectively. The specimens were subjected to various operating conditions to measure their traction and scuffing outcome (i) axially ground, (ii) chemically polished isotropic surfaces, and (iii) highly polished mirror-like surfaces.

Numerical investigation of sliding friction behaviour and mechanism of engineering surfaces

2019 ◽  
Vol 71 (2) ◽  
pp. 205-211 ◽  
Author(s):  
Xiaogang Zhang ◽  
Yali Zhang
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Sliding Friction ◽  
Normal Load ◽  
Numerical Results ◽  
Operating Conditions ◽  
Friction Mechanism ◽  
Content Type ◽  
Optimal Surface ◽  
Friction Behaviour

Purpose This study aims to investigate the sliding friction behaviour and mechanism of engineering surfaces. Design/methodology/approach A new numerical approach is proposed. This approach derives the macroscale friction coefficient from microscale asperity interactions. By applying this approach, the sliding friction behaviour under different operating conditions were investigated in terms of molecular and mechanical components. Findings Numerical results demonstrate an independent relationship between normal load and friction coefficient, which is governed by the saturated plastic ratio. Numerical results also demonstrate that under very small load, an increase in load increases the friction coefficient. In addition, numerical results confirm the existence of optimal surface roughness where the friction coefficient is the lowest. For the surface profiles used in the current calculation, an optimal surface roughness value is obtained as Rq = 0.125 μm. Originality/value This new approach characterizes the deterministic relationship between macroscale friction coefficient and microscale asperity molecular/mechanical interactions. Numerical results facilitate the understanding of sliding friction mechanism.

Set-Up of an Experimental Procedure for the Surface Smoothing of FDM Parts through Acetone Vapor

2019 ◽  
Vol 813 ◽  
pp. 447-452
Author(s):  
Antonio Coppola ◽  
Filomena Impero ◽  
Cuono Ruggiero ◽  
Fabrizio Scala ◽  
Antonino Squillace
Keyword(s):  
Surface Roughness ◽  
Structural Reliability ◽  
Fused Deposition Modeling ◽  
Operating Conditions ◽  
Physical Models ◽  
Post Processing ◽  
Basic Part ◽  
Fused Deposition ◽  
Smoothing Process ◽  
Set Up

Fused deposition modeling (FDM) is an additive manufacturing technology where three-dimensional physical models are manufactured by layer-by-layer deposition. However, the layered surface built with FDM suffers from poor surface quality and dimensional accuracy even for basic part geometries. This proves to be unacceptable and not satisfactory for most general purposes with the consequence of a decreased value of the final product. Several methods for post-processing were proposed to achieve fine surface of manufactured components. In particular, for components manufactured with polylactic acid (PLA) the chemical post-processing with dimethyl ketone (acetone), named vapor smoothing process, seems to be very promising to significantly improve the surface roughness. Moreover, acetone has the main advantage to have a low cost, low toxicity and high diffusion rate. However, this polishing procedure may dissolve the outer surface of the parts affecting the structural reliability of the part. In this work, a novel device, consisting of a cylindrical chamber in Pyrex, is set-up for the vapor smoothing process with acetone. The system is designed to permit the injection of a gas containing acetone at different concentrations and at different operating conditions (temperature, contact time). The samples used for the test are truncheon design manufactured using different printer settings; each truncheon is built at inclination angles varying from 0° to 45° in step of 5°. The variation of the surface roughness was investigated using a confocal microscope Leica DCM3D, equipped with the software LeicaScan and LeicaMap.

scholarly journals Using uniform design and regression methodology of turning parameters study of nickel alloy

2021 ◽  
Author(s):  
Shao-Hsien Chen ◽  
Chih-Hung Hsu
Keyword(s):  
Surface Roughness ◽  
Tool Wear ◽  
Nickel Alloy ◽  
Design Methodology ◽  
Cutting Tool ◽  
Uniform Design ◽  
Machining Time ◽  
Variable Parameters ◽  
Cutting Test ◽  
Set Up

AbstractThe nickel alloy has good mechanical strength and corrosion resistance at high temperature; it is extensively used in aerospace and biomedical and energy industries, as well as alloy designs of different chemical compositions to achieve different mechanical properties. However, for high mechanical strength, low thermal conductivity, and surface hardening property, the nickel alloy has worse cutting tool life and machining efficiency than general materials. Therefore, how to select the optimum machining parameters will influence the workpiece quality, cost, and machining time. This research will be using a new experimental design methodology to the cutting parameter planning for nickel-based alloy cutting test, and used the uniform design methodology to cutting test to reduce the number of experiments. Three independent variable parameters are set up, including cutting speed, feed rate, and cutting depth, and four dependent variable parameters are set up, including cutting tool wear, surface roughness, machining time, and cutting force. A nickel alloy turning parameter model is built by using regression analysis to further predict the I/O relationship among various combinations of variables. The errors between actual values and prediction values are validated. When the cutting tool wear (VB) is 2.72~6.18%, the surface roughness (Ra) is 4.10~7.72%, the machining time (T) is 3.75~8.82%, and the cutting force (N) is 1.54~7.42%; the errors of various dependent variables are approximately less than 10%, so a high precision estimation model is obtained through a few experiments of uniform design method.

The behaviour of heavily loaded line contacts with transverse roughness

1999 ◽  
Vol 213 (4) ◽  
pp. 309-320 ◽  
Author(s):  
C. J. Hooke
Keyword(s):  
Surface Roughness ◽  
Full Range ◽  
Numerical Results ◽  
Operating Conditions ◽  
Entrainment Velocity ◽  
Original Surface ◽  
Line Contacts ◽  
Transverse Roughness ◽  
Inlet Length

In heavily loaded, piezoviscous contacts the surface roughness tends to be flattened inside the conjunction by any relative sliding of the surfaces. However, before it is flattened, the roughness affects the inlet to the contact, producing clearance variations there. These variations are then convected through the contact, at the entrainment velocity, producing a clearance distribution that differs from the original surface. The present paper explores this behaviour and establishes how the amplitude of the convected clearance varies with wavelength and operating conditions. It is shown that the primary influence is the ratio of the wavelength to the inlet length of the conjunction. Where this ratio is large, the roughness is smoothed and there is little variation in clearance under the conjunction. Where the ratio is small, significant variations in clearance may occur but the precise amplitude and phasing depend on the ratio of slide to roll velocities and on the value of a piezoviscous parameter, c. The numerical results agree closely with existing solutions but extend these to cover the full range of operating conditions.

scholarly journals A 2-D model for Intermediate Temperature Solid Oxide Fuel Cells Preliminarily Validated on Local Values

Catalysts ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 36 ◽  
Author(s):  
Bruno Conti ◽  
Barbara Bosio ◽  
Stephen John McPhail ◽  
Francesca Santoni ◽  
Davide Pumiglia ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Operating Conditions ◽  
Solid Oxide ◽  
Intermediate Temperature ◽  
Physical Parameters ◽  
Local Concentration ◽  
Oxide Fuel ◽  
Molten Carbonate ◽  
Experimental Apparatus ◽  
Set Up

Intermediate Temperature Solid Oxide Fuel Cell (IT-SOFC) technology offers interesting opportunities in the panorama of a larger penetration of renewable and distributed power generation, namely high electrical efficiency at manageable scales for both remote and industrial applications. In order to optimize the performance and the operating conditions of such a pre-commercial technology, an effective synergy between experimentation and simulation is fundamental. For this purpose, starting from the SIMFC (SIMulation of Fuel Cells) code set-up and successfully validated for Molten Carbonate Fuel Cells, a new version of the code has been developed for IT-SOFCs. The new release of the code allows the calculation of the maps of the main electrical, chemical, and physical parameters on the cell plane of planar IT-SOFCs fed in co-flow. A semi-empirical kinetic formulation has been set-up, identifying the related parameters thanks to a devoted series of experiments, and integrated in SIMFC. Thanks to a multi-sampling innovative experimental apparatus the simultaneous measurement of temperature and gas composition on the cell plane was possible, so that a preliminary validation of the model on local values was carried out. A good agreement between experimental and simulated data was achieved in terms of cell voltages and local temperatures, but also, for the first time, in terms of local concentration on the cell plane, encouraging further developments. This numerical tool is proposed for a better interpretation of the phenomena occurring in IT-SOFCs and a consequential optimization of their performance.

scholarly journals Skewness and Kurtosis: Important Parameters in the Characterization of Dental Implant Surface Roughness—A Computer Simulation

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Karl Niklas Hansson ◽  
Stig Hansson
Keyword(s):  
Surface Roughness ◽  
Shear Strength ◽  
Roughness Parameter ◽  
Interface Shear Strength ◽  
Interface Shear ◽  
Implant Surface ◽  
Bone Response ◽  
Dental Implant Surface ◽  
Skewness And Kurtosis

The surface roughness affects the bone response to dental implants. A primary aim of the roughness is to increase the bone-implant interface shear strength. Surface roughness is generally characterized by means of surface roughness parameters. It was demonstrated that the normally used parameters cannot discriminate between surfaces expected to give a high interface shear strength from surfaces expected to give a low interface shear strength. It was further demonstrated that the skewness parameter can do this discrimination. A problem with this parameter is that it is sensitive to isolated peaks and valleys. Another roughness parameter which on theoretical grounds can be supposed to give valuable information on the quality of a rough surface is kurtosis. This parameter is also sensitive to isolated peaks and valleys. An implant surface was assumed to have a fairly well-defined and homogenous “semiperiodic” surface roughness upon which isolated peaks were superimposed. In a computerized simulation, it was demonstrated that by using small sampling lengths during measurement, it should be possible to get accurate values of the skewness and kurtosis parameters.

scholarly journals The Shear Strength Characteristics of Frozen Coarse Granular Debris

1984 ◽  
Vol 30 (106) ◽  
pp. 348-357 ◽  
Author(s):  
W.G. Nickling ◽  
L. Bennett
Keyword(s):  
Shear Strength ◽  
Normal Load ◽  
Strength Characteristics ◽  
Shear Tests ◽  
Critical Limit ◽  
Load Rate ◽  
Polycrystalline Ice ◽  
Saturated Sample ◽  
The Difference ◽  
Ice Content

AbstractThe effect of ice content and normal load on the shear strength characteristics of a frozen coarse granular debris was investigated. 31 shear tests were carried out in a modified shearbox allowing a sample temperature of (–1.0 ± 0.2)° C and a load rate of 9.63 × 10−4 cm/min. The tests showed that as the ice content of the frozen debris was increased from 0% (under-saturated) to 25% (saturated), sample shear strength was markedly increased. In contrast, sample shear strength was reduced as ice content was increased from 25% (saturated) to 100% (supersaturated). The changes in shear strength with increasing ice content were attributed directly to changes in internal friction and the cohesive effects of the pore ice. The shear tests also indicate that shear strength increases with increasing normal load up to a critical limit. Above this limit, dilatancy is suppressed causing the shear strength to decrease or remain relatively constant with increased normal load.The stress-strain curves of the 31 tests indicated that samples with higher ice contents tended to reach peak strength (τP) with less displacement during shear. Moreover, the difference between τp and τr (residual strength) was lowest for pure polycrystalline ice and highest for ice-saturated samples. The Mohr-Coulomb failure envelopes displayed very distinctive parabolic curvilinearity. The degree of curvature is thought to be a function of ice creep at low normal loads and particle fracture and crushing at high normal loads.

Sign in / Sign up

Export Citation Format

Share Document