Damage Tolerance Studies at the Blade Root Attachment of Aeroengines

Abstract

Fatigue is an important consideration in structural design for its safe continual newlineservice operation. Be it a bridge or a dam, building, rail vehicle, nuclear reactor, satellite, newlineaircraft, marine vehicles or small electronic devices. The problem of fatigue is newlineinterdisciplinary and offers immense scope for advanced work during design and newlinedevelopment as well as during operation and maintenance of structures. Today, many of newlinethe aircraft operating in India (Military and Civil) have at least about sixty percent of newlineageing fleet. Similar statistics is valid in respect of nuclear and thermal power plants. One newlinequestion that is often asked is how to extend the operating life of these safety critical newlinesystems, also with current ambitious programmes of the country in aerospace newlineengineering, nuclear power sectors etc., the importance of fatigue and fracture cannot be newlineover emphasized. newlineTo achieve maximum structural performance in an air craft gas turbine engine, all the newlinecritical components must be operated as close to their optimum design limits as possible. newlineThe rotating components such as blades and discs are critical components for the safety of newlinethe gas turbine engine. Since rotating disc of gas turbine possesses enormous energy, the newlinefailure of disc invariably leads to loss of aircraft, as it is not possible to contain the newlinefragments of the failed disc within the engine casing. Hence, disc burst is treated as the newlinemost catastrophic mode of failure and forms the basic safety issue in the usage of gas newlineturbine disc. newlineFurther, with the increasing demand for higher output efficiency coupled with rising newlinematerial costs have forced man-made structures to be very critically designed. newlineComponents are now pushed to their limits, having to operate at higher stress levels and newlinein more severe environment. Moreover, the consequences at stake should a component newlinefail are now greater than ever. Hence their design has to conform to the higher standards newlineof safety demanded. newlineBased on thorough literature survey it was inferred that t