Ramifications in Plant Stems as Concept Generators for Branched Technical Fiber-Reinforced Composites

Abstract

Fiber-reinforced composites are constantly optimized to meet high standards such as lightweight, a good load-bearing capacity and the ability to withstand high torsion and bending forces and moments. These mechanical loads are especially high in nodal elements and manufacturing of ramifications with an optimized force flow is one of the major challenges in many areas of fiber-reinforced composite technology, e.g. branching points of framework constructions in building industry, aerospace, ramified vein prostheses in medical technology or the connecting nodes of axel carriers. A biomimetic Top-Down-Process’ is currently applied to address this problem via an adaptation of innovative manufacturing techniques and the implementation of novel bio-inspired mechanically optimized fiber-arrangements and fiber-matrix-transitions. Hierarchically structured plant ramifications serve as concept generators for innovative, biomimetic branched fiber-reinforced composites. Promising biological role models are tree-like monocotyledons, including Dracaena and Freycinetia species. The ramifications in these plants show a pronounced fiber matrix structure and a special hierarchical stem organization, which markedly differs from that of other woody plants by consisting of isolated fiber-bundles running in a partially lignified ground tissue matrix. Our preliminary morphological and biomechanical analyses confirm that these lightweight ramifications possess mechanical properties interesting for a transfer into bio-inspired technical applications, such as a benign fracture behavior and good dynamic energy absorption. The results from the biological role models are currently transferred in the development of concepts for producing demonstrators and first prototypes in lab-bench scale of biomimetic branched fiber-reinforced composites.