Resisting metal fatigue in aeroengines, surface damage and surface treatments

 

Jim Byrne^*1, Ricardo A. Cláudio², Andrew Burgess¹

 

¹Department of Mechanical and Design Engineering, University of Portsmouth, Portsmouth, UK, PO1 3DJ.

²Department of Mechanical Engineering, ESTSetúbal / Instituto Politécnico de Setúbal, Campus do IPS, Estefanilha, 2910-761 Setúbal.

jim.byrne@port.ac.uk

 

ABSTRACT: The potential failure modes of components in aero engines are considered, with particular emphasis on fatigue, including high cycle fatigue (HCF), low cycle fatigue (LCF) and combined HCF/LCF. Some results of recent studies at Portsmouth of the influence of foreign object damage (FOD) on the fatigue behaviour under these different conditions of a fan and compressor material, Ti6Al4V alloy, are presented. A two parameter crack propagation model is considered.

The benefits in resisting fatigue through surface modification by the traditional process of shot peening has become well established for components such as turbine and compressor discs. The beneficial results of shot peening on the fatigue resistance of an advance nickel base superalloy at elevated temperature are presented together with the effects of subsequent surface scratch damage.

Keywords: High Cycle Fatigue, Low Cycle Fatigue, Foreign Object Damage, Shot Peening.

 

RESUMO:O presente artigo refere-se ao estudo de potenciais falhas em motores de avião, em particular falhas por fadiga, incluindo fadiga a elevado de ciclos, fadiga oligocíclica e fadiga combinada. São apresentados alguns resultados, obtidos em Portsmouth, da influência de dano provocado por objectos estranhos no comportamento à fadiga das pás da fan de compressor na liga Ti6Al4V. É considerado um modelo de propagação baseado em dois parâmetros.

Em componentes como discos de turbina e compressor, a melhoria de propriedades à superfície por processos tradicionais tem trazido grandes benefícios tem termos de melhoria de resistência à fadiga. São apresentados alguns resultados do benefício da grenalhagem, na resistência à fadiga de superligas de níquel a alta temperatura, em conjunto com os efeitos de um subsequente dano à superfície causado por um pequeno risco.

Palavras chave: Fadiga a elevado número de ciclos, fadiga oligocíclica, dano por objectos estranhos, grenalhagem.

 

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