Archives mensuelles : février 2017

Low hardness on bearing race

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An interesting paper in « Case studies in Engineering Failure Analysis » published on ScienceDirect.com.

Presence of decarburization on rolled bar coupled with out of square forging can lead to the presence of decarburized layer on one of the faces of a bearing race. This decarburized layer gives rise to low hardness on the face of the race. A series of examinations including micro-structural and macroscopic examinations on the defective samples revealed out of square forging as a root cause for the presence of the decarburized layer on a part of the one of the faces of a bearing outer race. This paper brings out the detail of investigation carried out.

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Fractography of a neck failure in a double-modular hip implant

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2017-02-23_09h32_35An article published in « Case Studies in Engineering Failure Analysis« , 2014.

The tapered joints of modular hip implants are prone to fretting and crevice-corrosion. This can lead to total failure in under a year, especially for heavier, more active implant recipients. In this study, fractography of a failed Profemur Z implant showed that a life limiting fatigue crack was nucleated on the anterolateral surface of the implant’s neck. The fatigue crack nucleation area appeared to have both more fretting damage and a higher corrosion rate than on other surfaces of the neck.

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Analysis of internal corrosion in subsea oil pipeline

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An interesting paper in  » Case study in Engineering Failure Analysis »published on ScienceDirect.com.

Failure of a subsea crude oil API 5L X52 steel pipeline which led to oil leakage has been reported to occur after 27 years in service. Some leaks were found to form at the bottom of the horizontal API 5L X52 steel pipeline near an elbow section which connected the pipeline to a riser.

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Issues to improve the safety of 18K370 steam turbine operation

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2017-02-23_09h04_00An article published by « E3S Web of Conferences 13, 04003 (2017)« .

The paper presents the process of improving the safety and reliability of operation the 18K370 steam turbines Opole Power Plant since the first failure in 2010, up to install the on-line monitoring system. It shows how the units work and how to analyse the contol stage as a critical node in designing the turbine. They have also briefly discussed the way of lifecycle management of individual elements. The presented actions could be considered satisfactory, and improve the safety of operating steam turbines of type 18K370.

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Evaluating the coupled thermo-mechanical stresses for an aluminum alloy piston used in a gasoline engine

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2017-02-02_09h44_08An article published in « The Journal of Engine Research » Vol. 42 (Spring 2016).

In the modern engines with higher compression ratios, severe pressures and
non-uniform heating up is occurred for the engine parts. The piston as the
most critical part among all automotive components has been the subject of
numerous studies on calculation of temperature distribution, but thermal
stress analyses are limited. In this study, the piston of gasoline engine XU7
which is widespread in Iran transport section is considered for thermomechanical
investigation.

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Failure analysis of a nose landing gear fork

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2017-02-02_09h26_14This paper presents a detailed analysis of a nose landing gear failure. The developed work comes following an accident occurred in which the nose of the landing gear’s fork of a light aircraft bent during landing. Nose gear failures are a high concern in the aviation industry. According to Federal Aviation Administration, in average 55% of aircraft failures occur during takeoff and landing while the remaining occurs during flight

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