Meeting Abstract

S4.7  Monday, Jan. 4  Functional Morphology and Biomechanics of Fruit Walls and Nut Shells: Concept Generators for Innovative Biomechanic Materials
SEIDEL, R.*; THIELEN, M.; SCHMITT, C.; BÜHRIG-POLACZEK, A.; FLECK, C.; SPECK, T.; Plant Biomechanics Group, Botanical Garden, University of Freiburg, Germany
; Plant Biomechanics Group, Botanical Garden, University of Freiburg, Germany; Plant Biomechanics Group, Botanical Garden, University of Freiburg, Germany; Foundry-Institute of the RWTH Aachen, Germany
; Materials Engineering, Berlin Institute of Technology, Germany
; Plant Biomechanics Group, Botanical Garden, University of Freiburg, Germany

The fruit walls of nuts and drupes are of special interest for the development of impact and puncture resistant materials. Their walls are hierarchically organized on at least five levels, the integral, macroscopic, microscopic, ultra structural and biochemical level. In addition to high hardness and toughness of the fruit wall of nuts and drupes with highly lignified endocarp the structural composition of some drupes, e.g. Cocos nucifera and the drupe related Citrus, indicates potential for shock absorption, an important function regarding the protection of the fragile kernel at free fall from heights of 10 meters or more. By detailed investigation of the Macadamia nut with its tough endocarp, Citrus maxima, possessing a large spongy mesocarp and Cocos nucifera, having a combination of fibrous mesocarp and tough endocarp, it becomes evident that those structures will provide excellent role models for impact and puncture resistant materials. Conducting high speed camera controlled free fall experiments of Citrus maxima from six metres height and comparing the potential energy of the fruits before and after impact (n=13) shows that a high proportion of the energy, possibly up to 90%, is dissipated by the fruit wall and pulp. Understanding the principles of how combining structure and material in biological tissues yields a fully functional protection layer will allow us to construct new lightweight materials of high impact and puncture resistance with a combination of high energy dissipation, benign failure and recovery from large deformations.