An article published in the « International Journal of Ethics in Engineering & Management Education » of july 2015.
Compress blade fails under several factors like high cycle fatigue, due to high rotational velocity, corrosiveness area, due to impinging foreign particle on compressor blade and also hard landing. This paper presents the failure analysis of compressor blade of helicopter engine.
A new article available online 10 November 2015 in « Case Studies in Engineering Failure Analysis ».
A temporary threadbar used for precast segmental construction broke during the post-tensioning stage before reaching the service load. Failure analysis showed that the premature failure of the bar was due to the presence of an arc strike. The arc strike effects on the material and threadbar integrity are studied. Read more….
An interesting article published on 4 November 2015 in the International Journal of ELECTROCHEMICAL SCIENCE.
In this paper an investigation on corrosion behaviour of welded joints was performed to facilitate determination the causes of preferential degradation by corrosion of the welded metal (WM) and the heat affected zone (HAZ), in a welded pipeline of grade ASTM A355P5, used in a petrochemical plant as transfer line between a thermal cracking heater and a column which are part of an atmospheric distillation and vacuum (DAV) unit. It was found that the corrosion of the weld analyzed in this research has resulted due to its dendritic structure (pearlite, ferrite, complex carbide, bainite and martensite in localized areas), which reveals the lack of post welding heat treatment (PWHT). Read more …..
A 
paper published in september 2016 on www.civil.northwestern.edu .
Abstract : The previously formulated model of the gravity-driven collapse of the twin towers of the World Trade Center on 9/11/2001 was shown to match all the existing observations, including the video record of the crush-down motion of the top part of tower during the first few seconds, the seismically recorded duration of collapse, the size distribution of particles caused by impact comminution of concrete floor slabs, the loud booms due to near-sonic lateral ejection velocity of air and dust, and precedence of the crush-down collapse mode before the crush-up. Nevertheless, di↵erent degrees of ductility, fracturing and end support flexibility of WTC columns could lead to an equally good match of these observations and remained uncertain, due to lack of test data. Recently, Korol and Sivakumaran reported valuable experiments that allow clarifying this uncertainty. They reveal that, under the assumptions of rigid end supports and unlimited ductility (or no fracturing), the energy dissipation in the WTC columns would have been at maximum 3.5-times as large as that calculated by the plastic hinge mechanism normally considered for small deflection buckling. This increase would still allow close match of all the aforementioned observations except for the first two seconds of the video. The proper conclusion from Korol and Sivakumaran’s tests, based on close matching of the video record, is that the fracturing of columns and the flexibility of end restraints must have significantly reduced the energy dissipation in columns calculated under the assumptions of no fracture and no end restraint flexibility.
L’analyse de défaillance est un processus méthodique permettant un diagnostic efficace des causes des différents modes de défaillance: rupture, usure, corrosion. La connaissance des origines des avaries facilite la mise en œuvre d’actions correctives et préventives afin qu’elles ne se reproduisent pas.
Pour l’industriel, fabricant ou utilisateur, une défaillance a souvent de lourdes conséquences :
– arrêt de production et pertes d’exploitation,
– litiges commerciaux et baisse d’image de marque,
– accidents humains,
… donc des conséquences financières!
Les experts Cetim et de ses centres associés : Cetim-Cermat, Cetim-Certec, Cetim-Ctdec, et partenaires : LRCCP(Laboratoire de Recherches et de Contrôle du Caoutchouc et des plastiques), ont avant tout un rôle de conseil !
Sollicitez les, ils vous accompagneront dans votre démarche !
Read the full text of an article reported on NASA Technical Reports Server
Ball bearings used inside the ISS Distillation Assembly centrifuge require superior corrosion and shock resistance to withstand acidic wastewater exposure and heavy spacecraft launch related loads. These requirements challenge conventional steel bearings and provide an ideal pathfinder application for 50-mm bore, deep-groove ball bearings made from the corrosion immune and highly elastic intermetallic material 60NiTi. During early ground testing in 2014 one 60NiTi bearing unexpectedly and catastrophically failed after operating for only 200 hr. A second bearing running on the same shaft was completely unaffected. An investigation into the root cause of the failure determined that an excessively tight press fit of the bearing outer race coupled with NiTi’s relatively low elastic modulus were key contributing factors. The proposed failure mode was successfully replicated by experiment. To further corroborate the root cause theory, a successful bearing life test using improved installation practices (selective fitting) was conducted. The results show that NiTi bearings are suitable for space applications provided that care is taken to accommodate their unique material characteristics.
L’Institut de Formation du Caoutchouc (IFOCA), basé à Vitry-sur-Seine (Val-de-Marne), a annoncé le lancement de deux nouvelles formations numériques.
Après le succès de sa première Formation en ligne ouverte à tous (Massive open online course ou MOOC), le centre de formation français aux caoutchoucs IFOCA vient de lancer deux sessions SPOC (Small private online course), des formations payantes abordant les thèmes suivants : Modélisation du comportement mécanique pour la simulation numérique et surtout Analyse de défaillance des pièces en caoutchouc.(…)
Source : L’IFOCA propose deux nouvelles formations numériques – Plastiques & Caoutchoucs Magazine
A case study published in « Case Studies in Engineering Failure Analysis » – April 2016.
In this study, the fracture failure of the 4Cr13 stainless steel linkage components in circuit breakers was studied. The microstructure and morphology of fracture surface were observed by scanning electron microscopy and optical microscopy. A micro-Vickers tester measured the hardness of the components. The tensile strength and strain of the components were determined by a universal testing machine. The results show that fracture failure mode was quasi-cleavage fracture, and some dimples and edges of cleavage were present on the fracture surface.
An article about a case study published in « Case Studies in Engineering Failure Analysis » – april 2016.
A temporary threadbar used for precast segmental construction broke during the post-tensioning stage before reaching the service load. Failure analysis showed that the premature failure of the bar was due to the presence of an arc strike. The arc strike effects on the material and threadbar integrity are considered.
A case study published in « Case Studies in Engineering Failure Analysis » – april 2016.
This paper investigates the failure of a rocker arm shaft of a passenger car. The shaft failed by brittle fracture across one of the four holes supporting the shaft into the cylinder head. The running distance of the engine just before failure was 40,626 km. These cracks may have been induced in the shaft by the non-uniform cooling during quenching in the course of heat treatment, or may be nucleated by repeated loading during service. This premature failure has occurred by the rapid crack propagation because of the lower fracture toughness of the martensite.
