Figure 1.
Location of strain gauges during the OLM and the SLM14 sensor
Table 1.
Correlation matrix for the available flight parameters
| Variable | SLMX14 | nz | Hb | VP | dh | dkl | dl | dv |
|---|---|---|---|---|---|---|---|---|
| SLMX14 | 1.00 | 0.93 | 0.43 | 0.61 | 0.37 | -0.30 | -0.03 | -0.07 |
| nz | 0.93 | 1.00 | 0.29 | 0.39 | 0.28 | -0.14 | -0.08 | -0.03 |
| Hb | 0.43 | 0.29 | 1.00 | 0.30 | 0.42 | -0.49 | 0.09 | 0.17 |
| VP | 0.61 | 0.39 | 0.30 | 1.00 | 0.22 | -0.46 | -0.08 | -0.15 |
| dh | 0.37 | 0.28 | 0.42 | 0.22 | 1.00 | 0.08 | -0.04 | 0.22 |
| dkl | -0.30 | -0.14 | -0.49 | -0.46 | 0.08 | 1.00 | -0.00 | 0.15 |
| dl | -0.03 | -0.08 | 0.09 | -0.08 | -0.04 | -0.00 | 1.00 | -0.15 |
| dv | -0.07 | -0.03 | 0.17 | -0.15 | 0.22 | 0.15 | -0.15 | 1.00 |
Table 2.
Linear regression model parameters for the SLMX14 equations using flight parameters
| Independent variables | R | R2 | free coefficient | a | b | c |
|---|---|---|---|---|---|---|
| nz | 0.9320 | 0.8686 | -64.1018 | 388.8242 | - | - |
| nz, Hb | 0.9459 | 0.8947 | -113.747 | 368.296 | 0.046 | - |
| nz, Hb, Vp | 0.9742 | 0.9491 | -231.156 | 332.524 | 0.032 | 0.726 |
Table 3.
Load sequence characteristics
| Sequence | SLMX14 | nz | nz+Hb | nz+Hb + Vp |
|---|---|---|---|---|
| Number of cycles | 52894 | 30434 | 28241 | 25348 |
| SFH | 270.6 | 266.7 | 267.7 | 271 |
Figure 2.
Technical drawing of the CT samples used in the test and the mount
Figure 3.
Test specimen mounted in the test stand, shown during (with a COD gauge) and after the test.
Table 4.
Dimensions of the CT specimens used in the test
| W [mm] | B [mm] | Width [mm] | Height [mm] | Holes [fi_mm] | Notch [mm] | CS [mm2] | Precrack [mm] | H [mm] |
|---|---|---|---|---|---|---|---|---|
| 48 | 8 | 60 | 57.6 | 12 | 21.6 | 307.2 | 1 | 3 |
Figure 4.
Crack propagation curves obtained for different load spectra