Cork-core CFRP sandwich cages for multirotor UAVs: An experimental comparison of modal response and impact protection
Measurement: Journal of the International Measurement Confederation, cilt.290, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 290
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.measurement.2026.122806
- Dergi Adı: Measurement: Journal of the International Measurement Confederation
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Compendex, INSPEC, Academic Search Ultimate (EBSCO), Engineering Source (EBSCO), Materials Science & Engineering Collection (ProQuest), Technology Collection (ProQuest)
- Anahtar Kelimeler: Agglomerated cork, Experimental modal analysis, Impact mitigation, Measurement uncertainty, Multirotor UAVs, Sandwich structures
- Eskişehir Osmangazi Üniversitesi Adresli: Evet
Özet
Caged multirotor drones operate in confined, obstacle-dense environments where repeated impacts and rotor-induced vibrations are unavoidable. A protective cage must mitigate impact loads while maintaining stiffness and damping with minimal mass. This study investigates cork-based sandwich structures as renewable core materials for protective drone cages. Three near-spherical cages of equal mass were manufactured with identical carbon-fiber-reinforced polymer (CFRP) face sheets and three different cores: fine-grained agglomerated cork, coarse-grained agglomerated cork, and PVC foam. Because the cores were matched in mass rather than in thickness, the study is presented as an equal-mass structural comparison of candidate cores rather than as an isolated material comparison. Dynamic behavior was characterized by impact-hammer modal testing, with frequency response functions screened by a coherence criterion and averaged over repeated impacts; dominant, well-separated modes were extracted by a single-degree-of-freedom fit and matched across cages using the modal assurance criterion check (MAC ≥ 0.80). Impact performance was quantified through instrumented drop tests from 0.2, 0.4, and 0.6 m using a high-g accelerometer. A measurement-uncertainty budget following the Guide to the Expression of Uncertainty in Measurement (GUM) was established, and the reported quantities are accompanied by their uncertainty or repeatability intervals. Relative to PVC foam, both cork cores raised the dominant natural frequencies and lowered the peak deceleration by 15–23 % at every drop height, and these differences exceeded the corresponding uncertainty and dispersion intervals. The two cork cores behaved similarly, with differences that generally fell within the expanded uncertainty; the data therefore support agglomerated cork as a lightweight, renewable core for impact-tolerant drone cages, while a definitive ranking of fine versus coarse cork would require replicated specimens. The higher natural frequencies are reported as a stiffness effect and not, by themselves, as a demonstration of in-flight vibration damping, which would require forced-response or operational measurements.