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Test and FEM calculation values of natural modes shapes and frequencies for sample ‘RX5L’
| No. | Test value | FEM calculation | Deviation [%] | ||
|---|---|---|---|---|---|
| Natural mode shape (experiment) | Natural frequency [Hz] | Natural mode shape (FEM) | Natural frequency [Hz] | ||
| 1 | Figure 6a | 144 | Figure 7a | 128 | 12.5 |
| 2 | Figure 6b | 163 | Figure 7b | 177 | 7.90 |
| 3 | Figure 6c | 200 | Figure 7c | 189 | 5.82 |
| 4 | Figure 6d | 469 | Figure 7d | 416 | 12.74 |
| 5 | Figure 6e | 700 | Figure 7e | 798 | 12.28 |
| 6 | Figure 6f | 990.5 | Figure 7f | 1,113 | 11 |
| 7 | Figure 6g | 1,283 | Figure 7g | 1,441 | 10.96 |
| 8 | Figure 6h | 1,553 | Figure 7h | 1,480 | 4.93 |
| 9 | Figure 6i | 1,811 | Figure 7i | 1,732 | 4.56 |
| 10 | Figure 6j | 3,070 | Figure 7j | 3,503 | 12.36 |
| 11 | Figure 6k | 4,838 | Figure 7k | 4,365 | 10.83 |
| FEM, finite element method. | |||||
Scattering of experimental data
| No. | Number of test/amount of scanning points | Average value | Coefficient of variation* | ||||
|---|---|---|---|---|---|---|---|
| 1/25 | 2/51 | 3/51 | 4/165 | 5/165 | |||
| 1 | 361 | 361 | 360 | 365 | 365 | 362.4 | 0.59 |
| 2 | 994 | 997 | 998 | 998 | 998 | 997 | 0.15 |
| 3 | 1,761 | 1,764 | 1,764 | 1,762 | 1,762 | 1,762.6 | 0.06 |
| 4 | 1,934 | 1,946 | 1,941 | 1,941 | 1,944 | 1,941.2 | 0.20 |
| 5 | 3,177 | 3,182 | 3,177 | 3,182 | 3,181 | 3,179.8 | 0.07 |
| 6 | 3,542 | 3,550 | 3,556 | 3,548 | 3,549 | 3,549 | 0.12 |
| 7 | 4,694 | 4,702 | 4,690 | 4,689 | 4,700 | 4,695 | 0.11 |
| 8 | 5,342 | 5,378 | 5,372 | 5,374 | 5,381 | 5,369.4 | 0.26 |
E-Moduli and Poisson’s values of the mono-materials
| Mono-material | Thickness [mm] | E-Modulus [GPa] | Poisson’s ratio |
|---|---|---|---|
| PP-PE | 0.2/0.3/0.6 | 1.45 | −0.45 |
| TS 245 | 0.24 | 197 | −0.247 |
| TS 245 | 0.49 | 191 | −0.276 |
| TH 470 | 0.49 | 210 | −0.264 |
Model parameters
| Monomaterial | Thickness [mm] | E-Modulus [GPa] | Poisson’s ratio |
|---|---|---|---|
| PP-PE | 0.33 | 1.23 | −0.39 |
| TS 245 | 0.45/0.26 | 194/192 | −0.245/0.3 |
Reference samples (sandwich sheets and metallic mono-materials)
| Mono-materials | ||||
| Notation | Material | Thickness [mm] | Notation | Grade |
| St. 0.24 | Steel | 0.24 | St. 0.24 | TS245 |
| St. 0.49 | 0.49 | St. 0.49 | TS245 | |
| St. 2 | 2.0 | St. 2 | NA | |
| Sandwich | ||||
| Thickness [mm] | Thickness [mm] | Skin | Core | |
| RP | 0.24/0.3/0.24 | 0.78 | TS245 | PP-PE |
| RH | 0.49/0.3/0.49 | 1.28 | TS245 | |
| RF | 0.49/0.6/0.49 | 1.58 | TS245 | |
| RD | 0.49/2.0/0.49 | 2.80 | TS245 | |
| RW** | 0.49/0.3/0.24 | 1.03 | TS245 | |
| RX*** | 0.49/0.3/0.24/0.3/0.24 | 1.57 | TS245 | |