Vol.3, No 13, 2003 pp. 689-706
UDC 539.388.1  620.193

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ASSESSMENT OF WIDESPREAD FATIGUE DAMAGE
IN THE PRESENCE OF CORROSION
G. Labeas, J. Diamantakos, Al. Kermanidis, Sp. Pantelakis
Laboratory of Technology and Strength of Materials
Department of Mechanical Engineering & Aeronautics
University of Patras, Patras 26500, Greece

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Crack growth and residual strength prediction of aircraft structures under Widespread Fatigue Damage (WFD) condition is a very complex task, mainly due to the lack of appropriate analysis tools able to efficiently handle multiple interacting cracks. In the present work an integrated methodology based on the sub-structuring technique of the Finite Element Method and able to treat WFD problems is used. Theoretical predictions are in good agreement with experimental results. The complexity of the problem increases when the effect of corrosion has to be taken into account. Experimental results presented in this paper indicate that crack growth characteristics are not strongly affected by corrosion at the early and medium stages of propagation (Paris regime). Yet, with increasing crack length, crack growth rate increases rapidly for the corroded material. The implementation of the effect of corrosion in assessing fatigue life of corroded structures under Multiple Site Damage is discussed.

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ODREDJIVANJE ŠIROKO RASPROSTRANJENOG OŠTEĆENJA USLED ZAMORA U PRISUSTVU KOROZIJE Napredovanje prsline i predvidjanje zaostale snage strukture letilica pri stanju široko rasprostranjenog oštećenja usled zamora (WFD) veoma je složen zadatak, prevashodno usled odsustva odgovarajućih sredstava analize kojim bi se efikasno moglo pozabaviti višestruke prsline koje jedna na drugu deluju. U ovom radu korišćena je integrisana metodologija zasnovana na tehnici podstruktuiranja metode konačnog elementa, i koja može da tretira WFD probleme. Teorijska predvidjanja slažu se sa eksperimentalnim rezultatima. Kompleksnost problema se povećava kada treba uzeti u obzir i uticaj korozije. Eksperimentalni rezultati koji su prikazani u ovom radu ukazuju da na karakteristike napredovanja prsline korozija nema snažan uticaj na ranim i srednjim stupnjevima širenja (pariski režim). Ipak, uz porast dužine prsline, stopa napredovanja prsline se rapidno povećava za korodirani materijal. Razmatra se ostvarenje uticaja korozije pri odredjivanju trajanja pri zamoru korodiranih struktura pri oštećenju na više položaja.