Low-Velocity Impact Properties of Sandwich Structures with Aluminum Foam Cores and CFRP Face Sheets
Abstract
:1. Introduction
2. Materials
2.1. Face Sheets
2.2. PUR Quantities and Manufacturing Process
2.3. Core Types
2.4. Sandwich Configurations
2.5. Specimen Geometry
3. Methods
3.1. Low-Velocity Indentation
3.2. Quasi-Static Indentation
3.3. Digital Image Correlation (DIC)
3.4. In Situ CT Indentation
4. Results
4.1. Low-Velocity Indentation
4.2. Quasi-Static Indentation
4.3. In Situ CT Indentation
5. Discussion
5.1. Conformity of LVI and Quasi-Static Indentation Behavior
5.2. Indentation Behavior
5.3. Influence of Sandwich Configuration
6. Conclusions
- LVI tests were conducted on a variety of sandwich configurations, accompanied and compared to quasi-static indentation tests, which were furthermore supported by DIC and CT measurements.
- The quasi-static indentation behavior of the investigated sandwich configurations is generally equal to the LVI behavior, including consistent force-indentation graphs and face sheet deformation. It was thus possible to describe the LVI behavior of the specimens with the more detailed data gained from the quasi-static and in situ CT tests, including DIC measurements.
- The failure of the first face sheet, the crushing of the core, and the failure of the second face sheet can be allocated in the force-indentation graphs, determined by observations made through in situ CT indentation tests, and consistent with literature.
- The face sheet configuration was shown to cause the load peaks observed at the start and the end of the indentation progress, and influence the maximum load level. Face sheets with higher face sheet fiber area weight, which could be generalized as ”face sheet thickness”, showed larger maximum force values. A woven architecture was shown to cause slightly higher maximum forces and less scatter than an otherwise equal NCF architecture. The DIC deformation pattern of woven face sheets also differs from the deformation pattern of NCF face sheets.
- The core type was shown to determine the overall load level and the section between the load peaks. CC cores were shown to cause higher load levels than NH and OC core structures, although the CC density was also higher.
- The PUR quantity stiffens the core structure. A large PUR quantity thus has the same effect as a denser core structure.
- The effects caused by each sandwich configuration parameter superpose, as was shown for an example of face sheet thickness and core structure.
Acknowledgments
Author Contributions
Conflicts of Interest
Abbreviations
CFRP | carbon fiber reinforced plastic |
CT | X-ray computed tomography |
GFRP | glass fiber reinforced plastic |
LVI | low-velocity impact |
NCF | non-crimp fabric |
PMMA | poly(methyl methacrylate), acrylic glass |
PUR | polyurethane |
Appendix A. Force-Indentation Graphs of Further Sandwich Configurations
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Component | Parameters | Sign |
---|---|---|
Face sheet fiber area weight | 160 g/m | 160 |
320 g/m | 320 | |
480 g/m | 480 | |
Face sheet fiber architecture | woven | w |
non-crimp fabric (NCF) | n | |
polyurethane (PUR) quantity | 75.5 g/m | 75 |
113.3 g/m | 113 | |
226.6 g/m | 226 | |
Core type | open-cell aluminum foam | oc |
closed-cell aluminum foam | cc | |
Nomex honeycomb | nh |
Configuration | Effective Density (g/cm) | Maximum Impact Force (N) | Absorbed Impact Energy (J) |
---|---|---|---|
160n75oc | 0.168 ± 0.005 | 1118.1 ± 281.1 | 18.87 ± 3.01 |
160n113oc | 0.179 ± 0.008 | 1275.0 ± 199.4 | 21.03 ± 4.45 |
160n113cc | 0.286 ± 0.017 | 2052.7 ± 475.5 | 33.82 ± 4.08 |
160n226oc | 0.192 ± 0.005 | 1165.2 ± 226,5 | 20.63 ± 2.69 |
160w75oc | 0.168 ± 0.016 | 1300.7 ± 290.3 | 22.22 ± 4.82 |
160w113oc | 0.188 ± 0.004 | 1371.5 ± 188.4 | 23.80 ± 4.92 |
160w113cc | 0.289 ± 0.040 | 2181.5 ± 480.4 | 38.79 ± 10.15 |
160w113nh | 0.126 ± 0.002 | 1285.3 ± 106.2 | 22.17 ± 1.91 |
160w226oc | 0.248 ± 0.013 | 1727.7 ± 326.6 | 38.11 ± 9.48 |
320n75oc | 0.180 ± 0.002 | 1444.9 ± 328.3 | 21.30 ± 3.40 |
320n113oc | 0.181 ± 0.003 | 1426.1 ± 141.3 | 22.57 ± 1.19 |
320n113cc | 0.295 ± 0.029 | 2109.2 ± 524.5 | 41.03 ± 15.73 |
320n113nh | 0.126 ± 0.003 | 1404.1 ± 267.8 | 19.99 ± 5.02 |
320n226oc | 0.188 ± 0.004 | 1492.1 ± 254.2 | 21.03 ± 5.76 |
320w75oc | 0.199 ± 0.008 | 2054.7 ± 418.7 | 30.29 ± 10.29 |
320w113oc | 0.211 ± 0.013 | 2109.3 ± 289.9 | 31.09 ± 2.35 |
320w113cc | 0.298 ± 0.027 | 2590.6 ± 435.2 | 47.45 ± 4.82 |
320w113nh | 0.143 ± 0.002 | 1662.8 ± 350.0 | 27.16 ± 7.64 |
320w226oc | 0.263 ± 0.014 | 2160.3 ± 316.2 | 47.35 ± 6.12 |
480w226oc | 0.279 ± 0.026 | 2478.3 ± 396.2 | 48.55 ± 9.96 |
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Rupp, P.; Imhoff, J.; Weidenmann, K.A. Low-Velocity Impact Properties of Sandwich Structures with Aluminum Foam Cores and CFRP Face Sheets. J. Compos. Sci. 2018, 2, 24. https://doi.org/10.3390/jcs2020024
Rupp P, Imhoff J, Weidenmann KA. Low-Velocity Impact Properties of Sandwich Structures with Aluminum Foam Cores and CFRP Face Sheets. Journal of Composites Science. 2018; 2(2):24. https://doi.org/10.3390/jcs2020024
Chicago/Turabian StyleRupp, Peter, Jonas Imhoff, and Kay André Weidenmann. 2018. "Low-Velocity Impact Properties of Sandwich Structures with Aluminum Foam Cores and CFRP Face Sheets" Journal of Composites Science 2, no. 2: 24. https://doi.org/10.3390/jcs2020024