Lewis M.W.J.,Quadrant Technology |
Tomkins B.,UK Forum on Engineering Structural Integrity
Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology | Year: 2012
In fatigue assessment of structures and components, it is now commonplace to use a defect-tolerant approach to account for the inevitable presence of surface and internal flaws, both detectable and undetectable. This approach has been applied to rolling bearings in an attempt to present contact stress limits as a function of defect size below which fatigue failure would not be expected. In essence, it is an extension to the existing rating life methods developed by Ioannides and Harris that incorporate a fatigue limit stress in the estimation of bearing life, a concept similar to that of the endurance limit in structural fatigue. Such a fracture mechanics approach to sub-surface initiated fatigue in rolling bearing steels containing non-metallic inclusions, based upon the work of Murakami, has led to an allowable contact stress limit as a function of maximum inclusion size (as estimated by extreme value analysis). An alternative, less conservative fracture mechanics based stress limit is the prevention of propagation of cracks formed on inclusions (termed 'butterflies') by shear (Mode II) loading. The approach has been developed by examination of butterflies formed in service in rolling element bearings manufactured in bainitic steel with maximum inclusion sizes in excess of 100 μm. The observed lack of micro-crack formation on inclusions and non-propagation of butterflies support the concept of a fatigue endurance limit that is related to the cleanliness of the bearing steel. © IMechE 2012.
Piazzoni C.,University of Milan |
Buttery M.,Quadrant Technology |
Hampson M.R.,Quadrant Technology |
Roberts E.W.,Quadrant Technology |
And 5 more authors.
Journal of Physics D: Applied Physics | Year: 2015
Fullerene-like MoS2 and WS2 nanoparticles can be used as building blocks for the fabrication of fluid and solid lubricants. Metal dichalcogenide films have a very low friction coefficient in vacuum, therefore they have mostly been used as solid lubricants in space and vacuum applications. Unfortunately, their use is significantly hampered by the fact that in the presence of humidity, oxygen and moisture, the low-friction properties of these materials rapidly degrade due to oxidation. The use of closed-cage MoS2 and WS2 nanoparticles may eliminate this problem, although the fabrication of lubricant thin films starting from dichalcogenide nanoparticles is, to date, a difficult task. Here we demonstrate the use of supersonic cluster beam deposition for the coating of complex mechanical elements (angular contact ball bearings) with nanostructured MoS2 and WS2 thin films. We report structural and tribological characterization of the coatings in view of the optimization of tribological performances for aerospace applications. © 2015 IOP Publishing Ltd.
News Article | December 27, 2016
Nick Batsikouras from Romeo, Michigan to be featured on HSN on January 2-3, 2017, introducing The Smart Diet Scale to more than 94 Million Homes. Leading entertainment and lifestyle retailer, HSN, announced that it has selected Nick Batsikouras, owner and CEO of The Smart Diet Scale - the World's Smartest Nutritional Food Scale with its Patented Four-Quadrant Technology, to appear on the HSN and introduce the product as part of HSN's American Dreams Initiative. The Smart Diet Scale is a wireless food scale with Bluetooth connectivity that calculates the nutritional value of an entire meal all at once, and directly transmits that information to a smartphone or tablet. The four-quadrant technology allows users to weigh their entire meal at one time while the Smart Diet Scale app (available from the App Store or Google Play) enables users to track their food intake. In addition to tracking over 650,000 food items, the Smart Diet Scale app also has over 200,000 grocery items and 80,000 restaurant items stored in its database for easy nutritional management. HSN launched its American Dreams initiative - a program designed to cultivate and introduce innovative new products to the marketplace - to discover new products and elevate entrepreneurs. NICK BATSIKOURAS will appear on HSN the following dates: For more information about HSN and American Dreams please visit http://www.hsn.com/ and follow our social channels: Facebook: https://www.facebook.com/HSN Instagram: https://www.instagram.com/hsn/ and Twitter: https://twitter.com/hsn Nick Batsikouras, Founder and CEO Smart Diet Scale - http://www.SmartDietScale.com Available for interviews and product demonstrations. 586.383.6734 Nick(at)SmartDietScale(dot)com About HSN: HSN is a leading entertainment and lifestyle retailer, offering a curated assortment of exclusive products and top brand names to its customers. HSN incorporates entertainment, inspiration, personalities and industry experts to provide an entirely unique shopping experience. At HSN, customers find exceptional selections in Health and Beauty, Jewelry, Home/Lifestyle, Fashion/Accessories, and Electronics. HSN broadcasts live to approximately 94 million households in the US 24/7 and its website - hsn.com features more than 50,000 product videos. Mobile applications include HSN apps for iPad, iPhone and Android. HSN founded 39 years ago as the first shopping network, is an operating segment of HSN, Inc. (Nasdaq: HSNI). For more information, please visit http://www.HSN.com, or follow @HSN on Facebook and Twitter.
Roffey P.,Quadrant Technology
Journal of Failure Analysis and Prevention | Year: 2014
An axle roller bearing failed due to full width axial cracking of the outer ring, an uncommon occurrence in roller bearings. Typically, this mechanism of failure is more consistent with inner rings that have been installed with excessive hoop stress from an incorrect interference fit on a rotating shaft. Fractography of the axial fracture revealed a shallow intergranular crack initiating from the surface of an external corner. The remainder of fracture propagation was high-cycle fatigue. Detailed metallographic analysis revealed hydrogen embrittlement on all four corners of the ring. Final machining processes, such as grinding and polishing performed on the side faces, raceway and outer surface had removed the embrittled material in these areas. This indicated the embrittlement process was not service related, but rather a result of the manufacturing heat treatment, most likely performed following the first rough cut of the ring prior to finishing. © 2014, ASM International.
Roffey P.,Quadrant Technology |
Davies E.H.,Quadrant Technology
Engineering Failure Analysis | Year: 2014
This paper describes a root cause failure investigation of a corroded AISI 304L stainless steel pipeline used to carry hydrocarbon gas. The corrosion was originally identified due to a leakage observed after removal of a section of lagging insulation. The investigation revealed however a three stage mechanism of attack had occurred; both intergranular cracking and transgranular cracking was present originating from both the internal and external surfaces. The process of attack occurred due to SSC from the internal surface resulting in CUI; the attack to the external surface then initiated SCC. A complex process of corrosion mechanisms was initially attributed to CUI, it was however due to internally initiated corrosion due to the combination of water carryover and the presence of corrosive species highlighting the importance of forensic examinations in oil and gas failures. © 2014 Elsevier Ltd.
Roffey P.,Quadrant Technology
Engineering Failure Analysis | Year: 2013
The mechanism of galvanised wire strand fracture in suspension bridge main cables is still a subject which is not fully understood and is often the focus of research studies. This current study presents findings from the third cable inspection performed on the Forth Road Bridge in Scotland. An extensive test programme which included metallographic wire examination, tensile testing and cyclic fatigue testing was carried out. From the findings a discussion of the possible mechanisms contributing to wire failure is provided. The results showed that tensile strength reduction is due to extremely localised corrosion, which propagates perpendicular cracks within individual wires, and was not directly related to the general corrosion severity classification used in the industry. The required depth of propagation to cause fracture was shown to range from as low as 150 μm, up to the radius of the wire. Possible mechanisms of crack initiation and propagation are considered and include; pitting corrosion, hydrogen assisted cracking, branched cracking and corrosion-fatigue. © 2013 Elsevier Ltd.
Roffey P.,Quadrant Technology
Engineering Failure Analysis | Year: 2012
This paper presents a case study summarising the failure analysis of a high nitrogen stainless steel femoral stem. The failure of the stem occurred after only 4.5. years in service by fatigue failure across the proximal region. The experimental work consisted of a visual inspection, macroscopic inspection, fractography and microscopic examination, surface profilometry and chemical analysis of the material. All metallurgical tests revealed the material to be satisfactory in terms of microstructure, hardness and composition. Inspection of the introducer slots revealed mechanical damage created during surgery to install the stem. The fatigue crack was shown to have initiated from a point of mechanical damage present in one of the introducer slots. This study highlights the detrimental effect of surface damage to initiate fatigue cracks under cyclic loading conditions and the need for greater awareness regarding the possibilities of creating stress raisers such as scratching, scoring and impacts which can lead to premature failure of prostheses. © 2011 Elsevier Ltd.
Roffey P.,Quadrant Technology
Journal of Failure Analysis and Prevention | Year: 2015
This paper presents the experimental process and findings of a forensic investigation of a failed fertilizer plant conveyor belt head roller shaft. A 25-year service life was expected but failure occurred following only 10 years. A gearbox which provided direct power to the roller had been replaced only several weeks earlier. The primary aim for the plant owner was to determine if the gearbox replacement had caused failure of the shaft, or, if the two incidents were unrelated. If incorrect installment of the gearbox had caused failure, liability would fall on the gearbox suppliers in terms of mitigation. However, it was revealed that the shaft had failed due to low-stress rotating bending fatigue, over an extended period of time. A premeditated change of material selection at the manufacturing stage, substituting carbon steel for 304L stainless steel, resulted in reduced corrosion resistance. Fertilizer ingredients tend to pose limited problems in their dry form in terms of corrosion; in the presence of moisture, however, can change the ingredients into aggressive corrosion species. Thus, corrosion allowed multiple fatigue cracks initiated from corrosion pitting under rotating bending load. The cracks then eventually joined together to form a single fatigue crack which propagated through the cross section. © 2015, ASM International.