Biomechanik von Säulenkakteen

Duration: June 2009 to June 2013, Leader: Prof. Dr. Christoph Neinhuis, Contact: Dr. Hannes Schwager

[Publications]
[Conference contributions]
[Collaborational partners]

Unlike tree branches, the side shoots of ramified columnar cacti feature distinct constrictions at their junction points. Notwithstanding the fact that such a necking in the region of the highest flexural stress represents an alleged structural weakness, the ramifications of columnar cacti provide extraordinary stability to the side shoots. Not even superposition of the branches dead weight with additional wind load causes significant distortion of the ramification.

With the objective to develop alternative design concepts for branched technical light-weight structures based on a deeper understanding of the junction point functionality, in particular the arrangement of the lignified vascular tissues in this region, biomechanical studies on columnar cacti were carried out at the Institute for Botany of the TU Dresden within the DFG priority program 1420 “Biomimetic Materials Research: Functionality by Hierarchical Structuring of Materials”.

The main focus of the research was the interdisciplinary knowledge transfer from basic botanical research to technological implementation. In this context biomechanical models of different columnar cactus species were developed with state-of-the-art engineering techniques. Finite Element Analysis (FEA) of these models served to analyze the stability of the cacti ramifications under static (dead weight) and dynamic (wind induced) loading.

This modeling process required precise knowledge of the functional anatomy and the material properties on all hierarchical levels of the investigated cactus species. For this purpose branched specimens from the Botanical Garden of the TU Dresden and other collections were examined concerning the functional morphology and the arrangement of the constituent tissues. In addition trunk and ramification segments were macerated to conceive the axial course of the vascular bundles. Based on the results of these macroscopic studies representative geometric models of the selected species were created with computer aided design (CAD) software. These CAD-models were refined with details from further examination: the material properties of each tissue were attained in mechanical tests; the fiber orientation of the vascular bundles in the trunk and the ramification were visualized by modern optical and radiographic means (e.g. 3D-laserscanning, micro-focus computer tomography etc.) and appropriate load assumptions concerning the wind induced forces were made.

Evaluating these models with finite element analysis (FEA) allowed to identify the contribution of each tissue to the stability of the cacti ramifications. In addition, zones of structural weakness were unveiled, which helped to derive alternative design instructions for branched technical fiber composite structures.

    Publications:

• Schwager H, Haushahn T, Neinhuis C, Speck T & Masselter T (2010) Principles of Branching Morphology and Anatomy in Arborescent Monocotyledons and Columnar Cacti as Concept Generators for Branched Fiber-reinforced Composites. Advanced Engineering Materials 12: B695–B698. Link
• Masselter T, Schwager H, Milwich M, Gude M & Speck T (2010) Verzweigte bio-inspirierte technische Faserverbundstrukturen. Konstruktion, Entwicklung, Management S1/2010 „Sonderheft Energie“: 60-61. Link
• Masselter T, Haushahn T, Schwager H, Milwich M, Nathanson R, Gude M, Cichy F, Hufenbach W, Neinhuis C & Speck T (2010) Biomimetic Fibre-Reinforced Composites Inspired by Branched Plant Stems. In: Brebbia CA & Carpi A (eds.): Design and Nature V. WIT Press, Southampton: 411 – 420. Link
• Cichy F, Danczak M, Schwager H, Neinhuis C, Gude M & Hufenbach W (2011) Simulation of Branched Biological Structures for Bionic Inspired Fibre-reinforced Components. Composites Theory and Practice 11: 304-309. Link
• Masselter T, Barthlott W, Bauer G, Bertling J, Cichy F, Ditsche-Kuru P, Gallenmüller F, Gude M, Haushahn T, Hermann M, Immink H, Knippers J, Lienhard J, Luchsinger R, Lunz K, Mattheck C, Milwich M, Mölders N, Neinhuis C, Nellesen A, Poppinga S, Rechberger M, Schleicher S, Schmitt C, Schwager H, Seidel R, Speck O, Stegmaier T, Tesari I, Thielen M & Speck T (2011) Biologically inspired products. In: Bar-Cohen Y (ed.) Biomimetics: Nature Based Innovation. CRC Press, Boca Raton: 377-429. Link
• Haushahn T, Schwager H, Neinhuis C, Speck T & Masselter T (2012) Plant ramifications inspire branched lightweight composites. Bioinspired, Biomimetic and Nanobiomaterials, 77-81. Link
• Müller L, Milwich M, Gruhl A, Böhm H, Gude M, Haushahn T, Masselter T, Schwager H, Neinhuis C & Speck T (2013) Biomimetisch optimierte verzweigte Faserverbundstrukturen mit hoher Tragfähigkeit. Melliand Textilberichte 2: 88-93. Link
• Schwager H, Masselter T, Speck T & Neinhuis C (2013) Functional Morphology and Biomechanics of Branch–Stem Junctions in Columnar Cacti. Proceedings of the Royal Society B 280: 20132244. Link
• Schwager H & Neinhuis C (2015) Kakteenverzweigungen als Vorbilder für die technische Bauteile. Kakteen und andere Sukkulenten 66: 43-48. Link
• Schwager H, Neinhuis C & Mauseth JD (2015) Secondary Growth of the Leaf and Bud Traces in Hylocereus undatus (Cactaceae) during the Formation of Branches or Flowers. International Journal of Plant Sciences 176: 762-769. Link
• Schwager H (2015) Functional Anatomy and Development of Cactus Ramifications. TU Dresden (Dissertation) Link

    Conference contributions:

• Schwager H & Neinhuis C: Branched Fibre Compound Structures Inspired by Columnar Cacti. Materials Science and Engineering Congress 2010, Darmstadt
  (August 24, 2010).
• Schwager H & Neinhuis C: Morphological and Anatomical Load Adaptations of Cactus Ramifications. Society for Experimental Biology Annual Main Meeting 2011, Glasgow
  (July 4, 2011).
• Schwager H, Haushahn T, Neinhuis C, Speck T & Masselter T: Functional Branching Morphology of Arborescent Monocotyledons and Columnar Cacti. European Congress on Advanced Materials and Processes 2011, Montpellier
  (September 12, 2011).
• Schwager, H. & Neinhuis C.: Functional Branching Morphology of Arborescent Columnar Cacti. 7th Plant Biomechanics International Conference 2012, Clermont-Ferrand
  (August 20-24, 2012). PDF Best Poster Award in the session Tree & Tools 2
• Schwager H, Maselter T, Speck T & Neinhuis C: Vom Kakteenholz zur bionisch optimierten Faserverbundstruktur. 11. Bionik-Kongress 2012, Bremen
  (October 26-27, 2012).
• Schwager H & Neinhuis C: Functional Anatomy, Biomechanics and Development of Cactus Ramifications. 21st Congress of the European Society of Biomechanics 2015, Prag
  (July 8, 2015)
• Schwager H, Hesse L, Masselter T, Speck T & Neinuis C: Alternative Gestaltungskonzepte für verzweigte Faserverbundstrukturen nach dem Vorbild pflanzlicher Verzweigungen.
  Werkstoffwoche 2015, Dresden
  (September 15, 2015).
• Schwager H & Neinhuis C: Funktionsanatomie und Entwicklung der Blatt- und Zweigspuren in Kakteenverzweigungen. 3. Holzanatomisches Kolloquium, Dresden
  (Oktober 2, 2015).

    Collaborational partners:

Prof. Dr.-Ing. Werner Hufenbach, Institute for Lighweight Engineering and Polymer Tehnology, Technische Universität Dresden
Prof. Dr. Thomas Speck, Plant Biomechanics Group, Albert-Ludwigs-Universität Freiburg
Dr.-Ing. Markus Milwich, Institute of Textile Technology and Process Engineering, Denkendorf

The research project Branched natural fibrous composites for improved technical components is funded by the German Science Foundation (DFG) within the priority program SPP 1420 “Biomimetic Materials Research: Functionality by Hierarchical Structuring of Materials.“