Bio-inspired, Flexible Structures and Materials - Biotechnologies and Biomimetics for Civil Engineering - page 277

technical problems by formulating a concise technical question which evolution
may have already developed an answer for. Elastic-kinetic structures may be
derived, for example, from flexible deployable systems found in nature. These can
be observed especially in movements of plants or plant organs. Of particular
interest are non-autonomous plant movements which usually show a clear inter-
relation of form, actuation, and kinetics. In the following section two strategies are
presented which may be used to extract principles from nature for bending-active
structures and compliant mechanisms.
12.3.1 Direct Methods in the Context of Compliant
Mechanisms
In general, the work with biological role models can be initiated by two different
biomimetic process sequences, which, in the further development of an iterative
design process, are often mixed. The basic processes are:
Bottom-up = biology push: In this approach new biomimetic research projects for tech-
nical implementation are born from new and promising results of fundamental biological
research. The first step of the process (…) is to analyse the biomechanics and functional
morphology of a biological system. In the next step quantitative analysis leads to a
principal and detailed understanding of the biological structures, shapes and functions. On
the abstraction level, which follows, separation of the principles discovered in the bio-
logical model takes place. Abstraction often proves to be one of the most important as well
as most difficult steps in a biomimetic projects. (Speck and Speck 2008 ,p.6)
Top-down = technology pull: A biomimetic project following the top-down process
typically starts with the work of an engineer. In this approach biomimetic innovations and
improvements are sought for in already existing technical products. These products might
either be in a final state of industrial development, or are often already successfully
established on the market. For a successful top-down process well founded expertise is
required from company representatives (engineers) as well as from fundamental
researchers (biologists), and also readiness to talk with the parties on both sides. The
improvement or further development of an existing product stands in the centre of the
cooperation during a top-down process. (Speck and Speck 2008 ,p.7)
So, the top down approach begins by defining the question. For instance, the
overriding question in the development of compliant mechanisms is the optimi-
sation of adaptability and energy efficiency of kinetic systems as well as the
lowering of their weight and maintenance costs.
When aiming for biomimetic solutions, a proven first step can be a screening of
natural concept generators with a high potential for translation into technical
applications. Usually, the most evolved and robust answers can be found in
organisms which developed under high selective pressure (Reith et al. 2007 ). Plant
movements, for example, are particularly adequate for translation into kinetic
architectural structures. Unlike animal locomotion, which is usually laid out for a
variety of complex movements, the actuation systems of plants are evolutionary