Towards the elaboration of the European Code of Practice for TMF crack growth

• In recent years, there has been an increasing interest towards the environmental impact of air travel. As a result, it is of vital importance to the European aviation industry to reduce the engine emissions. For this purpose, ACARE set new challenging targets aiming to reduce emissions, fuel consumption and raising temperature capabilities. This will ultimately be achieved by the introduction of novel engine design and new materials able to sustain complex loadings from take-off, cruise, descent and shut down. It is a prerequisite to understand the impact of such environments in current alloys.Specifically, Thermo-Mechanical Fatigue (TMF), which occurs at the rim of turbine discs, aerofoils and rear structures need to be assessed. At these locations, the harsh thermal transients during take-off and descent may cause the formation of cracks.  A previous European project on TMF, which ended in 2005, has been successful at evaluating and addressing issues related to thermo-mechanical fatigue testing. This project led to the elaboration of a code of practice for TMF studies, which has been implemented by testing houses and equipment manufacturers worldwide. A European project has recently been awarded, under the umbrella of both `Horizon 2020' and Clean Sky 2, aiming to evaluate and model TMF crack initiation and growth.TMF crack growth (CG) methods are essential to demonstrate that structural components meet the certification requirements of being tolerant at handling damages and the presence of melt anomalies. They are also needed to assess remnant lives in cracked turbine components such as vanes. However, crack growth in TMF loading cycles cannot be currently reliably measured experimentally nor predicted by existing CG models. Therefore, isothermal propagation data are used to conservatively handle TMF effects, which can lead to over-designed components and loss of engine efficiency. Our project aims to address those deficiencies.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Metallurgi och metalliska material (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Metallurgy and Metallic Materials (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Rymd- och flygteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Aerospace Engineering (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Teknisk mekanik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Applied Mechanics (hsv//eng)

Nyckelord

crack initiation

crack growth

high temperature

nickel-base superalloys

thermo-mechanical fatigue

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