Archives du mot-clef case study

Cracked Speed Boat Steering Wheel

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2015-10-19_13h53_57A Case study published in « Case Studies in Engineering Failures Analysis » of october 2015.

Failure of a cracked steering wheel is studied in this paper. Steering wheel, mounted on a speed boat, had cracks emanating from one of the fastener holes until final fracture occurred.Possible causes of crack occurrence include excessive fastener torque moment, fretting between fastener and hole combined with poor machining that left marks that serve as potential crack initiation points. Obtained results are valuable for predicting fracture behavior of the cracked steering wheel and can be taken as a reference for design and exploitation process of such component.

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Wire breakage of Tyre bead grade

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2015-10-18_11h50_39A new case study in « Case Studies in Engineering Failure Analysis » of October 2015.

Tyre bead grade wire is used for tyre making application. The wire is used as reinforcement inside the polymer of tyre. The wire is available in different size/section such as 1.6 mm to 0.80 mm thin Cu coated wire. During tyre making operation at tyre Manufacturer Company, wire failed frequently. In this present study, different broken/defective wire samples were collected from Wire Mill for details investigation of the defect. The analysis revealed that, white layer of surface martensite was formed and it was caused the final breakage of wire. In this study they have also discussed about the possible reason for the formation of such kind of surface martensite (hard-phase).

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Failure analysis of a leaked oil pipeline

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2015-10-18_11h39_48A new paper in « Case Studies in Engineering Failure Analysis« .

An oil pipeline embedded in an underground trench had failed. Through the accident investigation they found that there was a perforation at the leak point of the pipeline. After careful analysis it is concluded that the leakage of the pipeline was mainly caused by the liquid impingement erosion.

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Failure analysis of a Ti-6Al-4V ultrasonic horn used in cavitation erosion tests

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MekanicaA paper published in MECHANIKA. 2015 Volume 21(4): 272–276.

During the testing of the materials’ cavitation erosion resistance on vibratory systems by direct method (ASTM G32), the thread from the ultrasonic horn – test specimen connection, is subjected to fatigue. Operational experience has shown the occurrence of cracks and fractures in this area after a number of stress cycles that was lower than anticipated. The paper presents an analysis applied on four types of ultrasonic horns geometries: the original geometry with an external thread M12 and three modified geometries, with an internal thread M10 and M8. The four geometries were subjected to static analysis in order to determine the stress distribution. Based on static analysis, the behavior of the horns to fatigue was simulated and analyzed, determining the fatigue life, safety factors and optimal geometry.

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Failure analysis of edge discoloration of galvanized fuel tank

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An interesting case study of failure analysis of defect on the surface of some galvanized fuel tank will be published on October 2015 in Case Studies in Engineering Failure Analysis 

A peculiar type of edge discoloration defect on the surface of some galvanized fuel tank was observed, causing significant appearance problems. In the study, the surface defect was characterized by visual inspection, optical microscopy, scanning electron microscopy and energy dispersive spectroscopic analysis to understand the source and mechanism of the defect. The paper presents the results of the investigation.

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Failure analysis of a motor-car coil spring

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An interesting case study of failure analysis of a motor-car coil spring broken was published in Case Studies in Engineering Failure Analysis on December 2013. A damage of protective layer was the reason for corrosion occurrence. A combination of corrosion and fatigue caused the failure of the spring.

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A failure analysis study on the fractured connecting bolts of a filter press

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An interesting case study of failure analysis will be published in Case Studies in Engineering Failure Analysis in October 2015

The purpose of this study was to investigate the main causes of the co-fracture of sixteen connecting bolts of a filter press cylinder–piston system. Stress state of the bolts during the service conditions has been analyzed and the failure reasons were determined from the fractography analysis and gathered information. According to the obtained results, it was concluded that the bolts had failed by the fatigue mechanism. It seems that insufficient torque was used during assembly.

Read more at : A failure analysis study on the fractured connecting bolts of a filter press

Failure Analysis of a Polymer Centrifugal Impeller

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An other new case study of failure analysis had been published in october 2015 in Case Studies in Engineering Failure Analysis.

A failure analysis investigation was performed on a fractured polymer impeller used in a respiratory blower. A radial split down the impeller center was observed, with symmetric fracture faces about the impeller bore. 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.

Read more at : Failure Analysis of a Polymer Centrifugal Impeller.

Leg Weld Fatigue Cracks in Anhydrous Ammonia Nurse Tanks

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A new case study of failure analysis was published on  Case Studies in Engineering Failure Analysis, april 2015

In an accident in southwest Iowa, USA in 2012, an anhydrous ammonia nurse tank vented its entire cargo of 5500 liters (1500 gallons) of liquid ammonia to the atmosphere. Follow-up study of the failed tank revealed a through-crack along a weld used to connect the tank to its running gear. The authors recommend that side-angle ultrasound be considered for use in periodic nurse tank inspections.

via Leg Weld Fatigue Cracks in Anhydrous Ammonia Nurse Tanks.

A failure Study of a locking compression plate implant

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2015-05-03_11h57_31

 

 

 

 

An interesting  paper in « Case study in Engineering Failure Analysis » published on ScienceDirect.com. In this case study a failed locking compression plate was investigated. Such plating systems are used to provide the stability to fractured bone and fixation. The locking compression plate had been separated in two pieces. One of the fracture surfaces from the failed component was investigated for surface topographical features. The visual, optical and scanning electron microscopy results indicated the presence of beach marks, intermetallic inclusions, corrosion pits and striations indicating fatigue crack propagation and overload failure. Some corrosion damage also was documented on the fractography. This case study shows that corrosion may have initiated fatigue crack which grew by the activities of daily living causing the failure.

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