A failure study of the railway rail serviced for heavy cargo trains

An interesting paper published in Case Studies in Engineering Failure Analysis, Volume 1, Issue 4, October 2013.1-s2.0-S2213290213000461-gr2

In this case study, a failed railway rail which was used for heavy cargo trains was investigated in order to find out its root cause. The crack is supposed to be initiated from the weaker ferrite networks. Given all of that, the failed railway rail is considered to be caused by overload. It is of great importance to improve the welding technology, and control the load of train in order to prevent similar failure in future.

Source : A failure study of the railway rail serviced for heavy cargo trains

Handling abuse causes premature bearing failures

An article published in « Case Studies in Engineering Failure Analysis » .

A bearing, can fail prematurely due to a variety of factors like wrong choice of a design for the application, lack of or inadequate lubrication, impact loads, vibrations, environmental factors like operating temperature, corrosive media, moisture, dirt or handling abuse during transport, mounting, reinstallation and servicing.

Two case studies are presented here wherein abusive handling likely caused premature fatigue failure of ball bearings.

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Défaillances par corrosion : jeudi 28 septembre 2017 au Cetim Nantes

Mis en avant

Journée Technique

Des outils pour prévenir et guérir

La corrosion reste un redoutable ennemi industriel, et ce, en dépit des avancées scientifiques et des progrès technologiques de ces dernières décennies. Elle est encore aujourd’hui responsable d’un grand nombre d’avaries et touche de nombreux domaines.

Ses causes sont multiples et sa maîtrise fait appel à des compétences variées.Elle revêt différentes formes et un cas apparemment simple peut cacher un phénomène complexe. Sa détection et sa mesure sont souvent une affaire de spécialistes.

Ayez les bons réflexes et venez profiter de notre expertise à l’occasion de cette journée, qui vous aidera à prévenir et guérir ce mal industriel.

Participation gratuite – Inscription obligatoire et limitée à deux personnes par établissement

Pour en savoir plus et s’inscrire

Adapter les dentures aux déformations

Suite aux pannes à répétition sur la ligne de propulsion d’un navire d’exploration pétrolière de la CGG, le Cetim en a identifié les causes et fourni les éléments pour y remédier en gardant le bateau en exploitation.

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Le Cetim est le leader français de l’analyse de défaillances et de l’expertise mécanique. Sa démarche, globale et multicompétences, traite la défaillance depuis ses origines jusqu’à la mise en place de solutions concrètes. 1 000 nouveaux cas sont traités chaque année.

Care and Maintenance of Bearings

Une publication intéressante chez SNR (NTN Corporation) qui présente les différents cas de défaillance pouvant affecter des roulements.

Pour accéder au document cliquez ici

Et si vous rencontrez un problème de défaillance de roulement n’hésitez pas à contacter les experts du Cetim.  En confiant votre expertise au Cetim, centre technique indépendant et neutre, vous êtes assuré d’une approche objective, compétente et factuelle.
Ses équipes dédiées pratiquent l’analyse des défaillance au quotidien et s’engagent sur des diagnostics.
Savoir pourquoi est son cœur de métier.
Savoir quoi faire est son atout, pour que vous tiriez de cet événement une nouvelle force de compétitivité !
Le Cetim est leader français en analyse de défaillances mécaniques, enrichi de son expérience de 30 ans, de 1000 nouveaux cas traités par an dans tous les domaines de la mécanique.

In vivo shell-like fractures of veneered-ZrO2 fixed dental prostheses

A non commum case study of failure analysis published in october 2014 in « Case Studies in Engineering Failure Analysis« .

Fractographic analyses are performed in two fixed dental prosthetic reconstructions made of ZrO2 frameworks covered by a veneering ceramic that fractured during function in the mouth. Internal thermal residual stresses and occlusal surface defects from localized contact overloading were found to precipitate the fracture in Case 1, whereas extreme occlusal surface damage from sliding chewing contact was determinant in the fracture of Case 2. The interface between the veneering ceramic and the ZrO2 framework was unaffected by the fractures.

Source : In vivo shell-like fractures of veneered-ZrO2 fixed dental prostheses

Grooving corrosion of seam welded oil pipelines

A paper published in « Case Studies in Engineering Failure Analysis« , october 2014.

24” pipeline carrying oil was failed in the form of longitudinal crack at the 6 O’clock position resulting in oil spill. The failed pipe was investigated to reveal the main cause of its failure. The procedure of investigation was built on studying the intact pipe, rupture area, parent material, and intact weld. Cracks were originated from weld defected sites, initiated by grooving corrosion, propagated by inertia at the normal designed pressure condition, and stopped when stress relief is attained.

Source : Grooving corrosion of seam welded oil pipelines

Weld failure analysis of 2205 duplex stainless steel nozzle

A publication in « Case Studies in Engineering Failure Analysiss, october 2014.

Failure analyses of weld joint between the nozzle and the head of the reactor made of 2205 duplex stainless steel was performed by optical microscopy (OM) and scanning electron microscopy (SEM). Cracks were found in HAZ of the weld. The depth of the cracks is equal to the thickness of the inner weld. Localized uneven distribution of ferrite/austenite with 80-90% ferrite in weld is found. Results show that the cracks occurred along columnar granular with cleavage fracture. Poor weld process probably results in these cracks.

Source : Case Studies in Engineering Failure Analysis

Failure analysis of interfering part of a steam turbine journal bearing

An article published in « Case Studies in Engineering Failure Analysis« , octobre 2014.

Journal bearings as so sensitive parts of steam turbines are very susceptible to failure through different mechanisms of wear, fatigue and crush during service conditions. Failure occurring through these mechanisms lead to turbine completely shut down as a result of interfering in working conditions of bearing different parts. In this paper, failed interfered part of a journal bearing related to a 320,000 kW steam turbine was examined. The studies were revealed that the bearing part loosing and inappropriate clearance can produce relative displacements under cyclic gradient loading. This condition was detrimental for the service life of turbine journal bearing via failure through fretting fatigue mechanism.

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Failure analysis of re-bars during bending operations

Failure_analysis_of_Rebar

An article published in « Case Studies in Engineering Failure Analysis« , october 2014.

This  paper highlights failure investigation of a failed rebar during bending operations. From fractography and microstructural analysis it is confirmed that the rebar sample failed in brittle manner due to through harden martensitic structure and which indicates that there is some anomaly in water box resulting in these premature failures.

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