Article

Journal of Materials Science

, Volume 49, Issue 1, pp 43-51

Production and properties of a precision-cast bio-inspired composite

  • Sebastian F. FischerAffiliated withFoundry-Institute, RWTH Aachen University Email author 
  • , Marc ThielenAffiliated withPlant Biomechanics Group, Botanic Garden, Faculty of Biology, University of Freiburg
  • , Philipp WeißAffiliated withFoundry-Institute, RWTH Aachen University
  • , Robin SeidelAffiliated withPlant Biomechanics Group, Botanic Garden, Faculty of Biology, University of Freiburg
  • , Thomas SpeckAffiliated withPlant Biomechanics Group, Botanic Garden, Faculty of Biology, University of Freiburg
  • , Andreas Bührig-PolaczekAffiliated withFoundry-Institute, RWTH Aachen University
  • , Matthias BünckAffiliated withAccess e.V

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Abstract

The article presents the production and investigation of a bio-inspired metal–metal-composite inspired by the pomelo peel. The pomelo fruit is able to withstand a fall externally undamaged, even from heights of over 10 m most likely due to the hierarchical structuring of its foamy peel, which represents a complex composite structure. Especially the foam’s struts, which are cells from the biological point of view, consisting of liquid-filled cores and shells (cell walls) with relatively high strength, give point to a technical adaptation. With the objective to make use of the pomelo’s ability to absorb impact energy, the design of a pomelo strut is abstracted and transferred to aluminium/aluminium–silicon-alloy (A356) composite tensile specimens. Testing results show that the properties of the individual materials can successfully be combined. After fracture of the outer high strength, but less ductile A356-shell, the applied stress can still be absorbed by deformation of the inner highly ductile pure aluminium. As a result, the ductility of a bio-inspired composite is significantly higher compared with an A356 tensile specimen. By varying the mould and casting temperatures, the relationship between the production parameters and the quality of the composite is shown. A reduced mould and casting temperature lowers the dendrite arm spacing in the A356 outer shell of the composite material thus leading to an increased tensile strength. The detected metal bond between the two materials is mainly influenced by the interaction between the casting and the mould temperature.