Current Issue : July - September Volume : 2016 Issue Number : 3 Articles : 5 Articles
To improve the efficiency of geared transmissions, prediction models are required. Literature provides only simplified models\nthat often do not take into account the influence of many parameters on the power losses. Recently some works based on CFD\nsimulations have been presented. The drawback of this technique is the time demand needed for the computation. In this work\na less time-consuming numerical calculation method based on some specific mesh-handling techniques was extensively applied.\nWith this approach the windage phenomena were simulated and compared with experimental data in terms of power loss. The\ncomparison shows the capability of the numerical approach to capture the phenomena that can be observed experimentally. The\npowerful capabilities of this approach in terms of both prediction accuracy and computational effort efficiency make it a potential\ntool for an advanced design of gearboxes as well as a powerful tool for further comprehension of the physics behind the gearbox\nlubrication....
The present study involves field testing of a tire-loading-based theory of pavement traction in place of the traditional coefficient of\nfriction. An associated hypothesis concerns the indicated existence of a fourth rubber force, surface deformation hysteresis, which\nis theorized to be independent of tire loading during tire sliding....
The friction coefficient, wear rate, and wear coefficient of the aluminum metal surface were measured\nat room temperature (300 K) with a pin-on-disk machine at a fixed load of 196.2 N. Two different testing\nconfigurations were adopted: (1) aluminum pin vs. Helix oil-on-steel disk (AHS) and (2) aluminum pin vs. 10%\nPolytron plus 90% helix oil-on-steel disk (APS). In the AHS configuration, the wear of the aluminum surface was\nfound to be approximately 70 m; however, in the APS configuration the wear dropped to 20 m, revealing a\nmarked decrement of one-third of the wear of aluminum. The volume wear rate of the metal in the unaided Helix\noil was estimated to be 1.28Ã?â??10ââ?¬â??3 mm3/min. The additive minimized the volume wear rate of the aluminum metal\nby orders of magnitude to 6.08Ã?â??10ââ?¬â??5 mm3/min. Similarly, the wear coefficient of the aluminum pin, calculated in\nthe AHS configuration, rendered a value of 1.27Ã?â??10ââ?¬â??10 m2/N. In the APS configuration, the same parameter was\n4.22Ã?â??10ââ?¬â??11 m2/N, that is to say, an order of magnitude lower than the preceding value. The observed coefficient of\nfriction for aluminum is 0.012 in Helix oil and falls to a remarkably lower value of 0.004 through the Polytron\nadditive. The experimental findings demonstrate that Polytron additive substantially lessens the wear of the\naluminum surface; in effect, the wear coefficient and the wear rate decline linearly. This singularity may be linked\nto the ability of Polytron to impregnate the crystal structure of the metal due to its ionic character and the consequent\nadherence to the metallic surface as a hard surface layer....
The friction of ice on other materials controls loading on offshore structures and vessels in the Arctic. However, ice friction is\ncomplicated, because ice in nature exists near to its melting point. Frictional heating can cause local softening and perhaps melting\nand lubrication, thus affecting the friction and creating a feedback loop. Ice friction is therefore likely to depend on sliding speed\nand sliding history, as well as bulk temperature.The roughness of the sliding materials may also affect the friction. Here we present\nresults of a series of laboratory experiments, sliding saline ice on aluminium, and controlling for roughness and temperature. We\nfind that the friction of saline ice on aluminium ...
Hot stamping of high strength steels has been continuously developed in the automotive industry to improve mechanical properties\nand surface quality of stamped components. One of themain challenges faced by researchers and technicians is to improve stamping\ndies lifetime by reducing the wear caused by high pressures and temperatures present during the process. This paper analyzes the\nlaser texturing of hot stamping dies and discusses how different surfaces textures influence the lubrication and wear mechanisms.\nTo this purpose, experimental tests and numerical simulation were carried out to define the die region to be texturized and to\ncharacterize the textured surface topography before and after hot stamping tests with a 3D surface profilometer and scanning\nelectron microscopy. Results showed that laser texturing influences the lubrication at the interface die-hot sheet and improves die\nlifetime. In this work, the best texture presented dimples with the highest diameter, depth, and spacing, with the surface topography\nand dimples morphology practically preserved after the hot stamping tests....
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