From natural branchings to technical joints: Branched plant stems as inspiration for biomimetic fibre-reinforced composites

Abstract

The manufacturing of nodal elements and/or ramifications with an optimised force flow is one of the major challenges in many areas of fibre-reinforced composite technology. The examples include hubs of wind-power plants, branching points of framework constructions in building industry, aerospace, ramified vein prostheses in medical technology or the connecting nodes of axel carriers. Addressing this problem requires the adaptation of innovative manufacturing techniques and the implementation of novel mechanically optimised fibre-reinforced structures. Consequently, the potential of hierarchically structured plant ramifications as concept generators for innovative, biomimetic branched fibre-reinforced composites was assessed by morphological and biomechanical analyses. Promising biological models were found in monocotyledons with anomalous secondary growth, i.e. Dracaena and Freycinetia, as well as in columnar cacti such as Oreocereus and Corryocactus. These plants possess ramifications with a pronounced fibre matrix structure and a special hierarchical stem organization, which markedly differs from those of other woody plants by consisting of isolated fibres and/or wood strands running in a partially lignified parenchymatous matrix. The angles of the Y- and T-shaped ramifications in plants resemble those of the branched technical structures. Our investigations confirm that the ramifications possess mechanical properties promising for technical applications, such as a benign fracture behaviour, a good oscillation damping caused by high energy dissipation and a high potential for lightweight construction. The results demonstrate the high potential for a successful technical tran sfer and led to the development of concepts for producing demonstrators in lab-bench and pilot plant scale that already incorporate 'solutions inspired by nature'. © 2013 WIT Press.