Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
Figure 9.
Figure 10.
Figure 11.
Figure 12.
Figure 13.
Figure 14.
Figure 15.
Experimental loading conditions and equivalents’ initial and final crack lengths for different stress ratios_
| R-ratio | a0 | af | Pmin | Pmax | P | N | ΔK0 | ΔKf |
|---|---|---|---|---|---|---|---|---|
| 0.1 | 3.34 | 7.875 | 0.115 | 1.149 | 1.034 | 382.000 | 5.395 | 22.696 |
| 0.2 | 3.31 | 7.14 | 0.237 | 1.184 | 0.947 | 569.700 | 4.85 | 16.88 |
| 0.3 | 3.365 | 7.365 | 0.348 | 1.16 | 0.812 | 547.000 | 4.22 | 15.90 |
| 0.5 | 2.735 | 6.28 | 1.25 | 2.50 | 1.25 | 240.000 | 5.535 | 15.82 |
Coefficient of Paris model_
| R-ratio | C | m |
|---|---|---|
| 0.1 | 1 · 10−8 | 3.645 |
| 0.2 | 1 · 10−8 | 3.7053 |
| 0.3 | 9 · 10−9 | 3.8712 |
| 0.5 | 5 · 10−8 | 2.9287 |
Mechanical properties of Al-Alloy 2024 T351_
| σ0.2 | σR | A | E | G | ν |
|---|---|---|---|---|---|
| 363 | 477 | 12.5 | 74 | 27.82 | 0.33 |
Dimension of fatigue specimens_
| Lt | L | l | h | B | a0 |
|---|---|---|---|---|---|
| 64 | 50 | 14.5 | 10 | 10 | 2 |
Chemical composition of Al-alloy 2024 T351_
| Elements | Si | Fe | Cu | Mn | Mg | Cr | Ti | Zn | Pb | Ni | Al |
|---|---|---|---|---|---|---|---|---|---|---|---|
| % | 0.105 | 0.159 | 3.97 | 0.449 | 1.5 | 0.05 | 0.018 | 0.109 | 0.056 | 0.02 | Rest |
Performance of Gamma model
| R-ratio | 0.1 | 0.2 | 0.3 | 0.5 | Mean value |
|---|---|---|---|---|---|
| %Dev | 4.520 | 3.892 | 1.220 | 5.200 | 3.708 |
| Prediction ratio | 0.961 | 0.968 | 0.988 | 0.951 | 0.967 |
The values of the constants of the adjustment curves_
| R-ratio | A | B | C | D | E | F |
|---|---|---|---|---|---|---|
| 0.1 | −44,955 · 104 | 282,743 · 103 | −71,01 · 103 | 8932.6 | −566.95 | 15.047 |
| 0.2 | −16,180 · 104 | 139,644 · 103 | −42.59 · 103 | 6101.5 | −424.49 | 12.113 |
| 0.3 | −10,975 · 104 | 603,626 · 103 | −132.9 · 103 | 14.714 | −823.39 | 19.20 |
| 0.5 | −56,762 · 104 | 384,000 · 103 | −104.6 · 103 | 14.404 | −1008.9 | 29.449 |