Failure analysis of piano strings

A new interesting paper in  » Engineering Failure Analysis » published on ScienceDirect.com.

This paper studies the failure cause of two types of piano strings. Were taken into consideration bass and acute strings of a grand piano concert broken up. The mechanisms leading to rupture the strings are examined. The critical points studied are : tuning pin, agraffe, compression points, environment, tuner.

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Case study: Analysis of the response of an aircraft structure caused by a propeller blade loss

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

One of the most severe failures in an aircraft provided with turboprops is an airscrew blade loss, this article is focused on the response of the structure after the break of a blade. The effects of stiffness and strength changes on the mounting system are analyzed. The research covers different parameters which can influence the phenomenon. The FEM model is suitable to simulate blade loss collapse sequence. The model has a perfectly-plastic material law and detects damage zones and failures…..Read more

Failure analysis of a pressure vessel

A  « Case Studies in E
ngineering Failure Analysis
 » published on ScienceDirect.com.

High strength low alloy (HSLA) steel with a nominal composition of 0.15C–1.25Cr–1Mo–0.25V is being extensively used in space programme. Owing to its ease of fabrication and welding, a tank was fabricated out of this alloy. The tank is used to contain strontium per chlorate which on combustion develop secondary thrust, effectively used during attitude control of satellite launch vehicle. During one of the routine qualification tests, a tank had failed at an internal pressure of 109 bar, against a designed proof pressure of 120 bar.

Failure was initiated from long seam weld of a cylindrical shell and propagated into the parent material thereafter. Detailed metallurgical investigation has been carried out to understand the cause of failure. …..Read more

Catastrophic failure of a carbon steel storage tank

A  « Case Studies in Engineering Failure Analysis » published on ScienceDirect.com

Catastrophic failure due to internal corrosion of a 10 m high, 8 m diameter steel storage tank containing approximately 350 m3 of waste solvent led to a significant environmental incident in 2009. An investigation was carried out to establish the root cause and to learn lessons that might prevent a reoccurrence.

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Failure of the Chassis of Roller Skates for Figure Skating

An interesting  paper in « Case study in Engineering Failure Analysis » published on ScienceDirect.com. This paper dealt with the analysis of a novel chassis for figure roller skates, made of P-AlMgSi alloy, which experienced a premature failure. An integrated approach had to be used to overcome the several criticalities of the study. The research led to the individuation of the primary cause of failure, standing in bending fatigue, due to the high number of jumps (i.e.: fatigue cycles) being performed during figure skating training. A solution to the problem was suggested, which led to an improved and optimized project of the chassis with positive outcomes (from the technical and mechanical points of view) in its use.

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Analysis and Optimization of Rocker ARM

An article published in the «  International Journal of Engineering Science and Computing« , September 2017.

A rocker arm is a valve train component in internal combustion engines. As rocker arm is acted on by a camshaft lobe, it pushes and opens either the intake or exhaust valve. This allows fuel and air to be drawn into the combustion chamber during the intake stroke or exhaust gases to be expelled during the exhaust stroke. Rocker arms were first invented in the 19th century and have been changed a little in function since then. Improvements have been made, however, in both efficiencies of operation and construction materials. About Rocker arm of Tata Sumo, vista. They will make the exact design of rocker arm of Tata sumo …..Read more

Fatigue Failure of wheel studs and nuits of light vehicules

Light vehicle is a potentially useful and efficient mode of transportation to be utilized in supporting the coal mine operation. However, due to the harsh road condition at the mine site, many light vehicles presently used are frequently experiencing a number of incidents caused by loose wheel. The occurrence of this loose wheel is very much related with some broken or damaged wheel studs and/or nuts of the vehicle. Type of failure and factors that may have caused the damage of the wheel studs and/or nuts of the vehicles are discussed in this paper…….

Read the  paper published on « Metalurgi »

Investigation on brittle fracture mechanism of a grade E cast steel knuckle

A paper published on « Case Studies in Ingineering Failure Analysis », on april 2014.

This paper investigated the brittle fracture mechanism of a grade E cast steel knuckle that is one of the key components of the coupler for railway wagon. The fracture morphology mainly shows the characteristic of cleavage, quasi-cleavage fracture as well as a little ductile fracture, so the failure of the knuckle can be attributed to brittle fracture distinctly. Moreover, a welding repair area with high hardness is also found in the fracture region, which might initiate micro-cracks on the surface of the knuckle. As a result, it can be inferred that under an impact load that did not exceed material fracture limit, the micro-cracks initiated from weld repair zone propagated rapidly into the inner matrix by continuously fracturing the dendrites along shrinkage porosity regions until the knuckle failed instantly.

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Pitting corrosion failure analysis of a wet gas pipeline

This paper, published on Engineering Failure Analysis, august 2017, présents corrosion failure analysis of an underground natural gas pipeline. The pipeline material grade is API 5L X65 with 10-in ID. The pipeline transfers multiphase fluid (gas, condensate, and water) from a gas well to a gas gathering plant, located 4200 m away from the well site. A portion of the line failed due to pitting corrosion under unknown circumstances. Based on visual and microscopic analyses and reviewing the background information, the following pitting corrosion sequences were identified: the oversized pipeline changed the dominant flow regime to “stratified”. In the stratified flow regime, the accompanying water phase accumulated in the pipelines’ low points. Considerable concentration of calcium ions along with high pH in CO2 media favored precipitation of calcium carbonate. The relatively thick scales adhered to the pipe surface were partially loosened and removed by the regional turbulent flow. This exposed the fresh steel surface to the corrosive media. The uncovered areas acted as the preferential anodic sites coupled with nearby large cathodic sites which were covered by scales and/or corrosion products. Under such conditions, pits emerged on the steel surface until one of them grew faster and failed the gas pipeline.

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Failure Analysis of Air Cooled Condenser Gearbox

A new article in « Case Studies in Engineering Failure Analysis » published on Sciencedirect.com.

Gears are very reliable components and normally work 5 to 6 years without failure.

This article is a case study of failure analysis of a gearbox which was failed in three months after its installation. The problem was identified by maintenance engineers through vibration monitoring of gearbox.

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