Abstract
The limpet tooth is widely recognized as nature's strongest material, with reported strength values up to 6.5 GPa. Recently, microscale auxeticity has been discovered in the leading part of the tooth, providing a possible explanation for this extreme strength. Utilizing micromechanical experiments, we find hardness values in nanoindentation that are lower than the respective strength observed in micropillar compression tests. Using micromechanical modeling, we show that this unique behavior is a result of local tensile strains during indentation, originating from the microscale auxeticity. As the limpet tooth lacks ductility, these tensile strains lead to microdamage in the auxetic regions of the microstructure. Consequently, indentation with a sharp indenter always probes a damaged version of the material, explaining the lower hardness and modulus values gained from nanoindentation. Micropillar tests were found to be mostly insensitive to such microdamage due to the lower applied strain and are therefore the suggested method for characterizing auxetic nanocomposites.
| Originalsprache | Englisch |
|---|---|
| Seiten (von - bis) | 447-453 |
| Seitenumfang | 7 |
| Fachzeitschrift | Acta biomaterialia |
| Jahrgang | 2023 |
| Ausgabenummer | 166 |
| DOIs | |
| Publikationsstatus | Elektronische Veröffentlichung vor Drucklegung. - 29 Apr. 2023 |
Bibliographische Notiz
Funding Information:Funding by the European Research Council under ERC Grant 771146 (TOUGHIT) is acknowledged. The authors thank Dr. Manuel Pfeifenberger, Dr. Markus Alfreider and Dr. Alexander Leitner for their support with sample preparation and testing. Further, we are grateful for Dr. Xianglong Peng's preliminary simulations during the early developments of the work. The TEM work was supported by National Research Foundation of Korea (NRF) funded by the Korea government (MSIT) (No. NRF-2020R1A2C2101735 ), Creative Materials Discovery Program (NRF- 2019M3D1A1078296 ), and, the KENTECH Research Grant ( KRG2022-01-019 ). The TEM work at Sungkyunkwan University (SKKU) was supported by Advanced Facility Center for Quantum Technology and the TEM work at KENTECH supported by Center for Shared Research Facilities .
Funding Information:
Funding by the European Research Council under ERC Grant 771146 (TOUGHIT) is acknowledged. The authors thank Dr. Manuel Pfeifenberger, Dr. Markus Alfreider and Dr. Alexander Leitner for their support with sample preparation and testing. Further, we are grateful for Dr. Xianglong Peng's preliminary simulations during the early developments of the work. The TEM work was supported by National Research Foundation of Korea (NRF) funded by the Korea government (MSIT) (No. NRF-2020R1A2C2101735), Creative Materials Discovery Program (NRF-2019M3D1A1078296), and, the KENTECH Research Grant (KRG2022-01-019). The TEM work at Sungkyunkwan University (SKKU) was supported by Advanced Facility Center for Quantum Technology and the TEM work at KENTECH supported by Center for Shared Research Facilities.
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© 2023
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