Page 384 - Biaxial Multiaxial Fatigue and Fracture

368 M. FONTE ET AL.

0 uAwo.05

0
lo"' 0 i
I 1
lo"*, 2 3 4 5 6 7,# 913 2030
AK [MPam ]

Fig. 4. Influence of R-ratio on FCGR in (OA) and (UA) A1 7049 alloy in vacuum.
The threshold values, Kmx, and C and m of Paris regime are summarised in Table 1
and Table 5, respectively, for different R-ratios.

~ AL7049 UA OA
[MPam] xih K,, Mth K,,
R air vacuum air vacuum air vacuum air vacuum
-1 8.24 11.0 4.12 5.5 9.04 14.90 4.52 7.45
-0.5 10.53 7.02
+0.05 7.45 10.67 7.84 11.2 4.50 5.40 4.90 5.68
+0.50 4.46 6.07 8.92 12.14 2.72 3.04 5.44 6.08
+0.80 2.80 4.35 15.10 21.75 1.90 2.91 9.49 14.55

AL 7049 UA dddN =C (AK) OA da/dN = C (AK)
[dcycle] C rn C m
R air vacuum air vacuum air vacuum air vacuum
-1 1~10.~' lxl0~ly 7.0 8.9 4x10-1~ ix~o-~~ 5.0 6.2
- 0. 5 3x10-" 7,3
+0.05 4~10"~ 1~10~~ 9.0 iX10-l3 ~~10.~~ 6.3
5.2
7.3
+0.50 4x10-" SxlO-'* 8.0 9.0 lxlO-" 4x10-" 5.1 6.2
+o.80 3xio-'3 ix1o-l7 8.1 9.0 4x10-" IX~O-~' 5.0 6.2