Archives du mot-clef case study

Failure Analysis of a Polymer Centrifugal Impeller

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A new case study published in Case Studies in Engineering Failure Analysis and posted on Sciencedirect.com.

The failure analysis investigation was performed on a fractured polymer impeller used in a respiratory blower. The brittle fracture morphology and defects within the impeller bore suggest that premature failure occurred because of multiple interacting factors including: intermittently high centrifugal velocities, imbalance bore and shaft conditions, defects within the bore caused by machining, and stress concentrations along the circumference of the impeller lip.

more at : Failure Analysis of a Polymer Centrifugal Impeller.

Failure analysis of the mobile elevating work platform

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An interesting  paper in « Case study in Engineering Failure Analysis » published on ScienceDirect.com. This paper outlines investigations of the accident which occurred during startup of the extending structure from the transport position of a mobile elevating work platforms. The investigation results presented in this paper are important because same or similar problems could arise in supporting structures of various types of transportation, construction and mining machines.

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Rupture d’un ressort de suspension de voiture

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Un cas concret d’analyse de défaillance rapporté par ScienceDirect.com et publié dans « Case study in Engineering Failure Analysis ».

Un dommage du revêtement anti-corrosion associé à un processus de fatigue est responsable de cette défaillance.

Pour lire l’article cliquez ici

Premature Failure of Dissimilar Metal Weld Joint at Intermediate Temperature Superheater Tube

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A new case study on Sciencdirect.com. This article was published in « Case Studies in Engineering Failure Analysis » of april 2015.

Premature Failure of EPRI recommended nickel based filler for Dissimilar Metal welds (DMW) such as in the present study has been investigated to determine the root causes. The mechanism involved a creep stage I process on the alloy steel side due to improper PWHT leading to undesirable carbides precipitation increasing the hardness. Therefore, the sensitivity of the welding to micro-cracking combined to bending stresses involvement induced a premature failure within short time of operation.

Read more at : Premature Failure of Dissimilar Metal Weld Joint 

Failure Analysis of Work Rolls of a Thin Hot Strip Mill

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A new interesting article published in « Case Studies in Engineering Failure Analysis »

In hot rolling mills, premature failure of rolls is a major concern as it adversely affects the mill operation and as well as production. Analysis of failed roll materials and actual rolling conditions in service are therefore necessary to understand the roll failure mechanism and thereby improve the wear resistance and extend the service life of rolls.

This work describes two different types of roll failure cases and their analysis which was carried out using destructive as well as non-destructive testing techniques (NDT). The cases are as follows:

(a)

Case I: Enhanced ICDP Bottom roll of fifth stand (F#5) which failed from the neck portion.

(b)

Case II: Analysis of sub-surface defect of ICDP rolls of the last stand (F#6

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Failure analysis of the pulleys during the press-fit assembling process

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A case study published in « Case Studies in Engineering Failure Analysis« .

This article highlights failure investigation of the pulleys during a press-fit assembling process. Pulleys are used to transmit power between rotational mechanical elements. Failure analysis was found that cooperative influence of higher carbon content with combination of elongated sulphides is reason for pulleys cracking. Steel cleanliness and homogeneous structure is an important factor for users of steel. The success of production process is connected with the optimal quality of steel.

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Failure analysis of work rolls of a thin hot strip mill

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A new case study of failure analysis published on Sciencedirect.com

In hot rolling mills, premature failure of rolls is a major concern as it adversely affects the mill operation as well as production. Analysis of failed roll materials and actual rolling conditions in service are therefore necessary to understand the roll failure mechanism and thereby improve the wear resistance and extend the service life of rolls.

The hot strip mill referred here consists of six stands wherein high chromium (Hi-Cr) iron rolls and Indefinite Chilled Double Poured (ICDP) cast iron rolls are being used for finishing rolling of the strips in the last two stands. The thin strip mill produces strips in the thickness range of 1.0–12.7 mm. This work describes two different types of roll failure cases and their analysis which was carried out using destructive as well as non-destructive testing techniques (NDT).

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Failure analysis of Co–Cr hip resurfacing prosthesis during solidification

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A paper published on january 2013 in « Case Studies in Engineering Failure Analysis« .

In this study a failure originated during solidification process into the femoral stem component of Hip Resurfacing prosthesis was investigated.  The results exhibited hot tearing, shrinkage porosity and metal oxide films due to inadequate heat dissipation during solidification process, as a consequence of poor investment casting ceramic mold configuration. Also in this paper was improved the casting design solving this kind of defects.

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Flywheel Starter Ring Gear Failures

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A new case study in failure analysis published by ScienceDirect.com. This technical paper summarizes the case study conducted for truck flywheel starter ring gears with diameter of 470 mm in order to reduce hardness variation by optimization of induction hardening and tempering processes.

 

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Failure analysis on unexpected wall thinning of heat-exchange tubes in ammonia evaporators

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ScienceDirect.com publishes a new « Case Studies in Engineering Failure Analysis« .

A failure incident of heat-exchange tubes in ammonia evaporators, which suffered from unexpected wall thinning after only one-year service with respect to their original design lifetime of fifteen years, was reported and carefully analyzed. The analysis results demonstrated that the unexpected wall thinning of tubes was primarily ascribed to multiple corrosion factors including uniform corrosion, pitting and interaction behavior between them. Relative failure mechanisms were discussed in detail and prevention measures were also proposed for ammonia evaporators under similar operating condition.

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