Issue 41

S.M.J. Razavi et alii, Frattura ed Integrità Strutturale, 41 (2017) 440-446; DOI: 10.3221/IGF-ESIS.41.55 444 2 2 q      (1) 0 1 q r q    (2) For semicircular notches under mode I and III loadings, the volume assumes the crescent shape shown in Fig. 4b, where Rc is the depth measured along the notch bisector line. The outer radius of the crescent shape is equal to R c +ρ/2, being ρ/2 the distance between the notch tip and the origin of the local coordinate system. 60 600 1.00E+04 1.00E+05 1.00E+06 1.00E+07 Nominal stress amplitude [MPa] Number of cycles to failure, N Torsion R=-1 Tension R=-1 Multiaxial R=-1  =1  =0° Multiaxial R=-1  =1  =90° Figure 3: Data from multiaxial tests from V-notched specimens. R c +r 0   R c r 0 (a) 2    R c  /2   (b) Figure 4: Critical volume for (a) V-shaped notches and (b) semicircular notches. The value of the SED averaged over the control volume carefully defined as presented above, has been calculated numerically by using the FE code ANSYS 12.0® both for V-notched and semicircular notched specimens. Fig. 5 shows the synthesis based on local SED. By comparing Fig. 5 with Fig. 3 it is evident that a single narrow scatterband has been obtained by means of the local energy. C ONCLUSIONS large bulk of results from multiaxial tests on V-notched and semicircular notched specimens made of 40CrMoV13.9 steel are discussed together with those obtained under pure tension and pure torsion loading from notched specimens with the same geometry. Altogether more than 120 new fatigue data (10 fatigue curves) are A