Bio-inspired, Flexible Structures and Materials - Biotechnologies and Biomimetics for Civil Engineering - page 279

The technical implementation in the form of a reduced scale or full scale
prototype lies not at the end, but rather amidst an iterative design process in which
feedback from real construction can reach as far back as fostering the under-
standing of the biological role model.

12.3.2 Indirect Biomimetic Approach

While the approach described above concentrates on singular phenomena and their
direct technical implementation, biomimetics can also support the design process
when looking at natural design and construction principles from a more general
perspective. Knippers and Speck ( 2012 ) highlight a number of design principles
that lead to structures with multiple network functions based on a multi-layered,
finely tuned and differentiated combination of basic components. Additionally,
Gruber ( 2011 ) selects some design strategies found in natural organisms that may
be of relevance for architectural constructions. From these sources, a list of natural
principles can be summarised that may be particularly applicable for the integrated
design approach pursued with bending-active structures and compliant mecha-
nisms. (Based on Knippers and Speck ( 2012 ) and Gruber ( 2011 ):
• Heterogeneity: Natural constructions are characterised by geometric

differentiation.
• Anisotropy: Many natural constructions consist of fibre reinforced composite
materials.
• Hierarchy: Biological structures are characterised by a multilevel hierarchical
structure.
• Multifunctionality: In botany, fibres simultaneously serve mechanical and
diverse physiological functions.
• Adaptability: Many short- and long term adaptations are known from natural
systems that adapt to their environment.

It should be noted at this point, however, that while all these principles already
provide a helpful guidance and inspiration for the design of bending-active struc-
tures and compliant mechanisms, this list makes no claim of completeness.
A detailed explanaition of these principles is given in VDI 6226 ( 2014 ). In fact, it
could be easily expanded by many other key aspects (e.g. redundancy, self-healing),
in order to address specific levels of perspective or to reach paramount objectives
such as closed material loops, effective energy conversion or sparing use of
resources.
Nevertheless, this first overview of natural principles already provides a useful
starting point. With focus on bending-active structures in the context of light-
weight structures, for example, it can be shown how these natural principles may
also be linked to the threefold engineering classification of lightweight structures
(Wiedenmann 1989 ):