Da (mm) 0 5 101520253035404550 z/B 0.0 0.5 1.0 Area average length Fatigue Figure 4: Optically measured fatigue and fracture crack-front shapes Das (mm) 0.25 2.5 25 250 Correction Ratio, CR (Daavg/Das) 0 1 2 3 4 5 6 7 8 Flat fracture Slant fracture s s R a a f T C D D + × = Daavg Das T Figure 6: Area average calibration curves for flat and flat-to-slant fracture surfaces Daavg (mm) 0 5 10 15 20 25 30 Load (KN) 0 5 10 15 20 25 30 35 40 C(T) 2024-T351 LT B = 6.35 mm W = 152 mm a/W = 0.4 ZIP3D (Yc = 6.8 deg) WARP3D (Yc = 6.35 deg) Flat - corrected Slant - corrected Daavg (mm) 0 102030405060708090 Remote Stress (MPa) 0 50 100 150 200 250 M(T) 2024-T351 B = 6.35 mm W = 1016 mm 2a/W = 1/3 Da is average of left and right tips Test 1 Test 2 Test 3 Yc = 6.35 deg With anti-buckling guides No anti-buckling guides (a) 152 mm C(T) (b) 1016 mm M(T) Figure 7: Corrected load-crack extension curves Das / B 0 1 2 3 4 5 6 7 Normalized Tunneling, T(a) / B 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Flat fracture [2] Scaled from B = 2.3 mm Slant fracture Scaled from B = 6.35 mm Figure 5: Tunneling magnitude for flat and flat-toslant fracture surfaces
RkJQdWJsaXNoZXIy MjM0NDE=