The paper investigates the running-in of hardened steel surfaces under mixed lubrication conditions. Pairs both equal and differing hardness were loaded together rolling/sliding conditions in a twin-disk rig, evolution surface topography was investigated using in-situ profilometry. Evaluation roughness parameters, height distributions profile relocation showed that these is rapid process where most prominent asperity tips undergo plastic deformation during initial loading cycles. Finally,...

Micropitting is a form of surface fatigue damage that happens at the roughness scale in lubricated contacts commonly used machine elements, such as gears and bearings. It occurs where specific film thickness (ratio smooth to composite roughness) sufficiently low for operate mixed lubrication regime, load part carried by direct asperity contacts. currently seen greater issue gear designers than regular pitting failure latter can be avoided control steel cleanliness. This paper describes...

There are many advantages to adhesively bonding stiffeners onto aircraft structures rather than using traditional mechanical fastening methods. However there is a lack of confidence the structural integrity bonded joints over time. Acousto-ultrasonic Lamb waves have shown great potential in health monitoring applications both metallic and composite structures. This paper presents an experimental investigation use acousto-ultrasonic for 3D scanning laser vibrometry. Two stiffened panels were...

As worldwide wind energy generation capacity grows, there is an increasing demand to ensure structural integrity of the turbine blades maintain efficient and safe generation. Currently, traditional non-destructive testing methods visual inspections are employed which require be out-of-operation during inspection periods, resulting in costly lengthy downtime. This study experimentally investigates potential for using Lamb waves monitor a composite blade that has been subject impact...

Abstract The paper presents the results of a thermal analysis set disk experiments carried out by Patching et al. to investigate scuffing. used crowned steel disks at 76-mm centers with maximum Hertzian contact pressures up 1.7 GPa. Experimental measurements friction were as basis for and their associated support shafts. Temperatures measured embedded thermocouples 3.2 mm below running tracks determine heat partition between faster slower in order match experimental calculated temperatures....

The phenomenon of fatigue in gears at the tooth root can be a cause catastrophic failure if not detected time. Where traditional low-frequency vibration may help detecting well-developed crack or completely failed tooth, system for early detection nucleation and initial propagation great use condition monitoring. Acoustic emission is potentially suitable technique, as it sensitive to higher frequencies generated by affected noise. In this article, static gear pair tested where was initiated...

Topography of surfaces may influence many processes in tribology including friction and adhesion. Its is usually taken into account various statistical models rough surfaces. Most these are based on an explicit or implicit assumption normality the asperity heights similar assumptions that involve Gaussian distributions. Recently it has been shown height distribution prepared by grinding not at both nano micro-scales, while topography epoxy resin replicas polishing papers having nominal sizes...

The detection of damage in gear teeth is paramount to any condition monitoring or structural health (SHM) tool for aerospace power transmissions such as those used helicopters. Current inspection techniques include vibration analysis and time-inefficient visual inspection. Acoustic Emission (AE) a very sensitive that has been successfully many SHM systems. Successful application AE will enable the optimisation box design (and hence weight saving) addition safety improvements. This paper...

A series of tests have been conducted to investigate fatigue damage characterization in corroded welded steel plates using structural health monitoring (SHM) techniques. Acoustic Emission (AE) is a non-destructive testing (NDT) technique with potential applications for locating and cracks service. In the present work, AE implemented characterize during crack evolution. It considered be based on relationship between RA value (the rise time divided by amplitude) average frequency recorded...

Abstract In today's high cost drilling environment, vibrations are recognized as the primary contributor to inefficiency. As such, accurate prediction, identification, and quantification of vibration along drill string has become increasingly important in order reduce costs. Near-bit measurements also particularly important, bit is often predicted be an cause vibration. This paper reviews a project within Ecuador, where mechanical damage bits been observed, clearly affecting performance....

For cellular structures with uniform geometry, cell size and distribution, made from a neo-Hookean material, we demonstrate experimentally that large stretching causes nonlinear scaling effects governed by the microstructural architecture strains at level, which are not predicted linear elastic theory. this purpose, three honeycomb-like square cells in stacked distribution were designed, where number of varied, while material volume ratio between thickness length walls fixed. These...

Abstract The article is concerned with thermal elastohydrodynamic lubrication (TEHL) modeling of rolling/sliding contacts and in particular relating the results such models to experiments. Two kinds lubricated contact experiments are considered: (i) traction where overall frictional resistance motion at TEHL measured (ii) heat partition where, addition resistance, temperature distribution contacting components flux into individual determined. discusses problem choosing an accurate...

Aircraft structural damage detection is becoming of increased importance. Technologies such as acousto-ultrasonic have been suggested for this application; however, an optimization strategy sensor network design required to ensure a high probability while minimizing mass. A methodology optimizing transducer placement adhesive disbond on metallic aerospace structures presented. Experimental data sets were acquired using three-dimensional scanning laser vibrometry enabling in-plane and...

A Reynolds stress model for turbulent boundary layers is used to study surface roughness effects on skin friction and heat transfer. The issues of primary interest are the influence character (element shape spacing) nature at high Mach numbers. Computations based compare satisfactorily with measurements from experiments involving variations in character, low-speed modestly supersonic conditions. more limited data base hypersonic numbers also examined reasonable success, although no...

The ability of a Structural Health Monitoring (SHM) system to automatically identify damage in composite structure is vital requirement demanded by end-users such systems. This paper presents the demonstration potential method. A fatigue specimen was manufactured and initially tested at 1Hz for 1000 cycles. Acoustic emission (AE) signals were recorded complete cycles periodically order establish base-line associated with undamaged specimens. then subjected impact create barely-visible (BVID)...

Gears typically operate in mixed lubrication conditions, where the lubricant film is too thin to prevent opposing surface asperities from interacting with each other. The likelihood/intensity of interactions indicated by Λ ratio: ratio smooth thickness roughness. Researchers have asserted that asperity are predominant cause acoustic emission (AE) healthy gear contacts. However, direct experiments on gears yet yield a clear relationship between Asperity AE (AAE) and ratio, this part due...

That motor sport is synonymous with advanced manufacturing probably true of the upper echelons such as F1, WRC and ALMS. However, at privateer level, many technologies, to an extent more traditional are beyond reach due a combination cost low production volumes. One technology that has potential make transition from level rapid casting technology. Rapid combines advantages casting, including greater flexibility during design stage effective structural behaviour, requirement for numbers...

Abstract Lubricated non-conformal contacts, such as between gear teeth, operate with high levels of mixed lubrication, where the amount direct asperity contact depends on operating parameters that influence film thickness. Understanding surface interaction is key to optimizing component life, and there considerable interest in sensitive monitoring methods Acoustic Emission (AE). Researchers have shown AE can detect subtle changes lubrication conditions, using sensors mounted directly...

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