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Mechanical properties of the aluminum alloy 2024 T351_
| yield stress (MPa) | ultimate tensile strength (MPa) | elongation (%) | cyclic strength coefficient, K′ (MPa) | Hardening coefficient, n |
| 318 | 524 | 12.8 | 652 | 0.104 |
Transition-related parameters_
| R | 0.01 | 0.10 | 0.33 | 0.54 | 0.70 | |
|---|---|---|---|---|---|---|
| T1 | ΔK | 8 | 7.5 | 6 | 6 | 5 |
| Kmax | 8.5 | 8.5 | 9 | 12 | 15 | |
| da/dN | 10−8 | 10−8 | 8 × 10−9 | 7.5 × 10−9 | 8 × 10−9 | |
| T2 | ΔK | 12 | 11 | 9 | 7 | 7 |
| Kmax | 12 | 12 | 12 | 15 | 23.3 | |
| da/dN | 1.30 × 10−7 | 1.30 × 10−7 | 1.70 × 10−7 | 7.2 × 10−8 | 2 × 10−7 | |
| T3 | ΔK | 19.8 | 18 | 21 | 13 | 12 |
| Kmax | 20 | 20 | 31 | 28 | 37 | |
| da/dN | 3 × 10−6 | 3 × 10−6 | 1.6 × 10−6 | 7 × 10−7 | 4 × 10−7 | |
Lifespan in number of blocks and relative error_
| Block | Number of blocks | Error (%) | |
|---|---|---|---|
| A | Measured Maachou et al. (2016) Present model Elber (1976) | 75120 | - |
| B | Measured Maachou et al. (2016) Present model Elber (1976) | 23900 | - |
| C | Measured Maachou et al. (2016) Present model Elber (1976) | 9600 | - |
| D | Measured Maachou et al. (2016) Present model Elber (1976) | 5500 | - |
Nomenclature
| symbols | Designations | symbols | Designations |
|---|---|---|---|
| da/dN | Crack growth rate (m/cycle) | Qi | Energy dissipated per cycle i |
| A | a dimensionless constant | Qenv | Enclosed energy (total area enclosed by all the cycles) |
| A | Elongation (%) | R | Load Ratio |
| B | Thickness (mm) | S1, S2 | Ductile and brittle Striations |
| D1, D2 | Dimples | US | Specific energy (J/m2) |
| Kmin, Kmax | Minimal and maximal stress intensity factor (MPa.m1/2) | W | Width (mm) |
| K′ | Cyclic strength coefficient (MPa) | α | The maximum specimen compliance during a cycle and Po |
| ΔK | Amplitude stress intensity factor (MPa.m1/2) | δ, δ′ | Crack opening displacement (mm) and differential crack opening (mm) |
| L | Length (mm) | γ | Energy necessary for creating surface (J/m2) |
| n | Hardening coefficient | μ | Shear modulus, MPa |
| Pmin, Pmax | Minimum and maximum load (N) | σc | Critical stress at fracture MPa |
| Po | Crack opening load (N) | σu | Ultimate tensile strength (MPa) |
| Q | hysteretic energy dissipated (J/cycle) | σy | yield stress (MPa) |
Nominal composition of the aluminum alloy 2024 T351_
| Element | Si | Fe | Cu | Mn | Mg | Cr | Zn | Ti | Al |
| Mean % | 0.90 | 0.22 | 4.46 | 0.66 | 1.5 | 0.01 | 0.04 | 0.02 | rest |
Loading conditions under constant amplitude loading_
| R | 0.01 | 0.10 | 0.33 | 0.54 | 0.70 | |||
|---|---|---|---|---|---|---|---|---|
| Pmin (daN) | 4 | 6 | 40 | 50 | 158 | 178 | 324 | 588 |
| Pmax (daN) | 400 | 600 | 400 | 500 | 480 | 540 | 600 | 840 |
| ΔP (daN) | 396 | 594 | 360 | 450 | 322 | 362 | 276 | 252 |
Different load levels with specific steps_
| Type of spectrum | Level 1 | Level 2 | Level 3 | Level 4 |
|---|---|---|---|---|
| N1 | N2 | N3 | N4 | |
| A | 1 | 1 | 1 | 1 |
| B | 10 | 10 | 10 | 2 |
| C | 10 | 10 | 50 | 2 |
| D | 10 | 10 | 100 | 2 |
Repartition of features at da/dN = 5 × 10−7 m/cycle_
| R | 0.10 | 0.70 |
|---|---|---|
| % Striations | 60 | 30 |
| % Dimples | 15 | 30 |
| Kmax [MPa.m1/2] | 13 | 31.27 |