Vol.3, No 13, 2003 pp. 647-655
UDC 531.22 539.388.1
THE EFFECT OF STRESS RATIO ON THE BEHAVIOUR
OF SHORT FATIGUE CRACKS IN ALUMINIUM ALLOYS
Chris A Rodopoulos, Eduardo R. de los Rios
Division of Aeronautical Applications, Structural Integrity Research
Institute
of the University of Sheffield (SIRIUS), Department of Mechanical Engineering,
The University of Sheffield, Sheffield, S1 3JD, United Kingdom
Email: C.Rodopoulos@sheffield.ac.uk
Based on the principles of the Fatigue Damage Map, the effect of the stress
ratio, R, on the boundaries of short crack growth is investigated. The
analysis reveals that the tendency of the material to short crack growth
is governed by the relation between the fatigue limit, sigmaFL,
and the cyclic yield stress, sigmacy. Materials
with low values of w=sigmaFL/sigmacy
loaded at high values of R exhibit negligible amount of growth irregularities,
allowing therefore the accurate representation by a Paris-Erdogan power
law.
UTICAJ ODNOSA NAPONA NA PONAŠANJE PRSLINA
SA KRATKIM ZAMOROM KOD ALUMINIJUMSKIH LEGURA
Na osnovu principa Mape oštećenja zamorom, istražen je uticaj odnosa napona,
R, na granice napredovanja kratke prsline. Analizom je otkriveno da se
tendencija materijala ka napredovanju kratke prsline rukovodi odnosom izmedju
granice zamora, sigmaFL, i cikličnog napona
popustljivosti, sigmacy. Materijali sa
niskim vrednostima w = sigmaFL/sigmacy
koji se opterećuju pri visokim vrednostima R pokazuju zanemarljivu količinu
nepravilnosti u napredovanju, čime omogućavaju tačno predstavljanje putem
Paris-Erdoganovog zakona snage.
