Robustness of Empirical Vibration Correlation Techniques for Predicting the Instability of Unstiffened Cylindrical Composite Shells in Axial Compression
Abstract
:1. Introduction
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- presenting results of one of the largest test programs to-date concerning the application of VCT for evaluating the axial buckling load of unstiffened cylindrical CFRP shells;
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- proposing an empirical modification of the existing VCT analysis that increases the accuracy of estimates of the buckling load;
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- evaluating the robustness of VCT with respect to variations in shell geometry, mounting and loading methods, and the preload.
2. Empirical VCT Techniques
3. Materials and Methods
3.1. Material
3.2. Manufacture of Shells
3.3. Tests
3.3.1. Characterization of Shell Thickness
3.3.2. Shell Buckling Tests
3.3.3. Characterization of Vibration Response
4. Results and Discussion
4.1. Buckling Loads and Modes
4.2. Vibration Spectra and Modes
4.3. VCT-Based Prediction of the Critical Load
5. Conclusions
Author Contributions
Funding
Conflicts of Interest
References
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Longitudinal Young’s Modulus E11, GPa | Transverse Young’s Modulus E22, GPa | In-Plane Shear Modulus G12, GPa | Poisson’s Ratio ν12 | ||
---|---|---|---|---|---|
Tension | Compression | Tension | Compression | ||
116.4 | 91.7 | 6.7 | 6.4 | 3.6 | 0.34 |
Shell Geometry | Load Introduction | Critical Load Pb, kN | ||
---|---|---|---|---|
Diameter D, mm | Height H, mm | Wall Thickness t, mm | ||
100 | 200 | 0.294 (0.001) 1 | Hemispherical joint | 3.05 (0.21) 1 |
0.273 (0.010) | Parallel plates | 3.65 (0.49) | ||
400 | 0.298 (0.005) | Hemispherical joint | 2.97 (0.39) | |
0.355 (0.019) | Parallel plates | 4.96 (0.29) | ||
300 | 150 | 0.359 (0.014) | Parallel plates | 5.63 (0.21) |
300 | 0.336 (0.046) | 3.88 (0.51) |
Cylinder Diameter and Height, mm | Loading | Cylinder Number | Buckling Load Pb, kN | Load Range in Vibration Tests | VCT-Predicted Buckling Load | ||||
---|---|---|---|---|---|---|---|---|---|
M1 | M2 | ||||||||
Min. P/Pb | Max. P/Pb | PVCT, kN | Relat. Error δ, % | PVCT, kN | Relat. Error δ, % | ||||
D = 100 H = 200 | Hemi- spherical joint | 01 | 3.20 | 0.05 | 0.97 | 3.61 | 12.9 | 3.34 | 4.5 |
02 | 2.90 | 0.05 | 0.99 | 3.40 | 17.4 | 3.17 | 9.3 | ||
Parallel plates | 03 | 3.35 | 0 | 0.93 | 3.50 | 4.7 | 3.26 | 2.5 | |
04 | 4.24 | 0 | 0.94 | 4.26 | 0.4 | 4.03 | 5.0 | ||
05 | 4.42 | 0 | 0.89 | 3.95 | 10.5 | 3.85 | 12.8 | ||
06 | 3.29 | 0 | 0.94 | 3.41 | 3.7 | 3.2 | 2.6 | ||
07 | 3.55 | 0.09 | 0.93 | 3.87 | 9.1 | 3.59 | 1.2 | ||
08 | 3.50 | 0 | 0.95 | 4.17 | 19.3 | 3.77 | 7.7 | ||
09 | 3.19 | 0 | 0.95 | 3.19 | 0.2 | 3.07 | 3.5 | ||
D = 100 H = 400 | Hemi- spherical joint | 01 | 3.15 | 0.08 | 0.97 | 4.08 | 29.4 | 3.66 | 16.2 |
02 | 3.23 | 0.04 | 0.99 | 3.43 | 6.3 | 3.27 | 1.2 | ||
03 | 2.52 | 0.08 | 0.96 | 3.04 | 20.8 | 2.83 | 12.4 | ||
Parallel plates | 04N | 4.67 | 0.08 | 0.93 | 4.77 | 1.9 | 4.48 | 4.2 | |
05N | 4.96 | 0 | 0.88 | 4.91 | 0.9 | 4.51 | 9.0 | ||
06N | 5.26 | 0.10 | 0.95 | 4.9 | 6.8 | 4.92 | 6.4 | ||
D = 300 H = 150 | Parallel plates | 02 | 5.61 | 0 | 0.87 | 4.8 | 14.4 | 4.84 | 13.8 |
04N | 5.85 | 0 | 0.98 | 6.49 | 11.0 | 5.84 | 0.1 | ||
05N | 5.44 | 0 | 0.92 | 6.0 | 10.4 | 5.22 | 4.0 | ||
D = 300 H = 300 | Parallel plates | 03 | 3.29 | 0 | 0.65 | 2.14 | 34.9 | 2.15 | 34.6 |
04N | 4.24 | 0 | 0.97 | 4.57 | 8.0 | 4.27 | 0.7 | ||
05N | 4.11 | 0 | 0.89 | 3.84 | 6.5 | 3.71 | 9.8 |
Relative Length Parameter of Shell | Mean Relative Error of Prediction δ, % | |
---|---|---|
M1 | M2 | |
21 | 11.9 | 6.0 |
42 | 7.3 | 5.3 |
54 | 8.7 | 5.5 |
99 | 11.0 | 8.2 |
Loading and Boundary Conditions | Mean Relative Error of Prediction δ, % | |
---|---|---|
M1 | M2 | |
Steel ring, hemispherical joint | 17.4 | 8.7 |
Steel ring, parallel plates | 5.8 | 5.5 |
Potted, parallel plates | 10.1 | 5.7 |
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Skukis, E.; Jekabsons, G.; Andersons, J.; Ozolins, O.; Labans, E.; Kalnins, K. Robustness of Empirical Vibration Correlation Techniques for Predicting the Instability of Unstiffened Cylindrical Composite Shells in Axial Compression. Polymers 2020, 12, 3069. https://doi.org/10.3390/polym12123069
Skukis E, Jekabsons G, Andersons J, Ozolins O, Labans E, Kalnins K. Robustness of Empirical Vibration Correlation Techniques for Predicting the Instability of Unstiffened Cylindrical Composite Shells in Axial Compression. Polymers. 2020; 12(12):3069. https://doi.org/10.3390/polym12123069
Chicago/Turabian StyleSkukis, Eduards, Gints Jekabsons, Jānis Andersons, Olgerts Ozolins, Edgars Labans, and Kaspars Kalnins. 2020. "Robustness of Empirical Vibration Correlation Techniques for Predicting the Instability of Unstiffened Cylindrical Composite Shells in Axial Compression" Polymers 12, no. 12: 3069. https://doi.org/10.3390/polym12123069