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Microstructural features influencing the mechanical performance of the Brazil nut (Bertholletia excelsa) mesocarp

  • Brazil nut (Bertholletia excelsa) fruits are capable of resisting high mechanical forces when released from trees as tall as 50 m, as well as during animal dispersal by sharp-teethed rodents. Thick mesocarp plays a crucial part in seed protection. We investigated the role of microstructure and how sclereids, fibers, and voids affect nutshell performance using compression, tensile and fracture toughness tests. Fractured specimens were analyzed through scanning electron microscopy (SEM) and microtomography (microCT). Mesocarp showed high deformability (strain at max. stress of ~30%) under compression loading, a critical tensile strength of ~24.9 MPa, a Weibull modulus of ~3, and an elastic modulus of ~2 GPa in the tensile test. The fracture toughness, estimated through the work of fracture of SENB tests, reached ~2 kJ/m2. The thick and strong walls of mesocarp cells, with a weaker boundary between them (compound middle lamella), promote a tortuous intercellular crack path. SeveralBrazil nut (Bertholletia excelsa) fruits are capable of resisting high mechanical forces when released from trees as tall as 50 m, as well as during animal dispersal by sharp-teethed rodents. Thick mesocarp plays a crucial part in seed protection. We investigated the role of microstructure and how sclereids, fibers, and voids affect nutshell performance using compression, tensile and fracture toughness tests. Fractured specimens were analyzed through scanning electron microscopy (SEM) and microtomography (microCT). Mesocarp showed high deformability (strain at max. stress of ~30%) under compression loading, a critical tensile strength of ~24.9 MPa, a Weibull modulus of ~3, and an elastic modulus of ~2 GPa in the tensile test. The fracture toughness, estimated through the work of fracture of SENB tests, reached ~2 kJ/m2. The thick and strong walls of mesocarp cells, with a weaker boundary between them (compound middle lamella), promote a tortuous intercellular crack path. Several toughening mechanisms, such as crack deflection, breaking of fiber bundles, fiber pullout and bridging as well as crack branching, occur depending on how fiber bundles and voids are oriented.zeige mehrzeige weniger

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Metadaten
Autor*innen:M. Sonego, Mauro Madia, M. Eder, C. Fleck, L. A. Pessan
Dokumenttyp:Zeitschriftenartikel
Veröffentlichungsform:Verlagsliteratur
Sprache:Englisch
Titel des übergeordneten Werkes (Englisch):Journal of the Mechanical Behavior of Biomedical Materials
Jahr der Erstveröffentlichung:2021
Organisationseinheit der BAM:9 Komponentensicherheit
9 Komponentensicherheit / 9.4 Integrität von Schweißverbindungen
Verlag:Elsevier Ltd.
Jahrgang/Band:116
Erste Seite:104306
DDC-Klassifikation:Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurwissenschaften und zugeordnete Tätigkeiten
Freie Schlagwörter:Brazil nut Mesocarp; Mechanical properties; Microstructure; Toughening mechanisms
Themenfelder/Aktivitätsfelder der BAM:Material
Material / Degradation von Werkstoffen
DOI:10.1016/j.jmbbm.2020.104306
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:08.02.2021
Referierte Publikation:Ja
Datum der Eintragung als referierte Publikation:08.02.2021
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