25-68 PROPAGAREA FISURII LA OBOSEALĂ AXIAL- EXCENTRICĂ. MODELE DE STUDIU
THE CRACK PROPAGATION AT ECCENTRICALLY
TENSILE FATIGUE TEST. STUDY MODELS
The study consists in crack propagation analysis in a plate specimen
CT model with side notch, made by a R520 steel. The specimen is loaded to a
eccentrically tensile test. The loading asymmetry factors are: R = 0.1 and R =
0.3, and the loading temperature is the room temperature, T = 293K.
The defect seeding rate in the specimen material marked as da/dN
was analysed by the empiric mathematical models: 1° – a second degree
polynomial method of approximation; 2º – according to Paris formula and, 3° –
respectively to Walker model. By using the three methods, there was
determined the crack propagation rate variation da/dN versus the crack length
variation a1, respectively versus the stress intensity factor ΔK.
Keywords: cyclic, request coefficient of asymmetry, cracking, cracking
speed, intensity factor in blood (FIT)
Cuvinte cheie: solicitare ciclică, coeficient de asimetrie, fisură, viteză
de fisurare, factor de intensitate a tensiunii (FIT)
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