Bionics research project BISS delivers ground-breaking
material concepts
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Auxetics: Unique natural protection decoded and transferred - Project goal: Better protection for BMW Group employees
Munich. Lighter protective clothing, tougher helmets,
more stable protectors: New materials with up to 20-per-cent-better
protective properties are the result of the BISS research project
headed by the BMW Group. What is unique is that all advances are based
on designs borrowed from nature – BISS stands for Bio-Inspired Safety Systems.
The consortium of seven partners spent three years researching and
developing alternative design and material concepts for the bionics
project. The BMW Group worked alongside adidas, ORTEMA, phoenix and
uvex, as well as the Institute of Textile Technology and Process
Engineering Denkendorf, Germany, the Department of Polymer Engineering
at the University of Bayreuth and the Plant Biomechanics Group of the
University of Freiburg, with additional support from partners such as
the company Innovationsmanufaktur in Munich. The German Federal
Ministry for Education and Research subsidised the project as part of
its “Technical Textiles for Innovative Applications and Products –
NanoMatTextil” programme.
Models: Pomelo fruit with shock absorbers; scales create
complete protective system
Biological models like the pomelo fruit benefit from highly effective
impact protection. So, even when it falls from a high tree, for
example, the fruit does not split open and the insides remain largely
undamaged. Its rind is also extremely light. Another example: The
scales of fish and many reptiles overlap to create a composite system
that stiffens under load to provide protection against injury.
Alligators’ protective armour, on the other hand, works in part by
distributing force to neighbouring scales.
The initial aim of the research project was to analyse the tissue
formation, cell structure and functioning of these protection
mechanisms and explore their suitability for use in
industrially-manufactured products. From there, the next step was to
refine the corresponding fibre composites, layer structures and fibre
orientation. The project then went on to examine how functions that
had previously been difficult to reconcile, like “crash protection”,
“penetration resistance” and “damping”, could be combined in
innovative protective systems using layering modelled on biological structures.
Up to 20 per cent lighter, tougher, more stable materials
The results now available have exceeded expectations: Prototypes
designed from natural models are up to 20 per cent lighter, tougher
and more stable than materials generally used today. They can be
produced economically and processed for the intended purposes. The
high level of functional efficiency achieved by biologically-inspired
protective equipment also saves material. This not only makes both
product and production more sustainable, but also less expensive.
Outlook: Easy-to-wear protection for BMW workers with
bio-blueprint
Technology-forecasting experts at the BMW Group believe the most
important learnings for the company lie in new approaches for enhanced
employee protection. Gloves and protective inserts made from bionic
materials, for example, can protect workers on the assembly line from
sharp-edged car-body parts. The low weight, breathable design and
flexibility of the research models mean that movement is barely
restricted. Other potential applications include new forms of
protective equipment for motorcyclists. Research models of crash
helmets and protectors offering the same level of protection weighed
considerably less than conventional models available on the market.
More safety, less weight for athletes
Sporting goods manufacturers have also identified significant
advantages for their products. As part of the project, uvex developed
new design principles based on biological models and created a new
kind of cushioning material for ski and bicycle helmets. With
cushioning properties 10 to 20-per-cent better than conventional
materials, this will create even safer helmets that exceed safety
requirements. Adidas also believes the research opens the door to
creating future protective clothing for basketball and football
players, for example. ORTEMA sees major opportunities for innovative
equipment for athletes in the findings. Through the development of
biologically-inspired materials, the manufacturer of special sports
equipment, individual orthotics and high-end protectors for numerous
sports was able to further improve the protective features of many of
its products and, at the same time, meet the high ergonomic demands
for protective sports gear.
phoenix, a specialist for product development using 3D data and 3D
printing, also participated in BISS. The service company developed
special production concepts to enable products to be manufactured
economically from innovative materials. In modern manufacturing
processes, especially Additive Layer Manufacturing (ALM) and rapid
manufacturing, production is controlled directly using 3D product data.
Background: Auxetic materials respond to pressure in unusual ways
The unique protective properties of biological models essentially lie
in their hierarchical design. The rind of the pomelo is one of these
so-called auxetic materials, which responds completely differently to
pressure than conventional structures: Where conventional material
gives way and becomes thinner under the pressure point, auxetic
material compresses and hardens faster. A further characteristic of
this atypical stress/strain behaviour is that the material actually
becomes thicker when stretched, rather than thinner. Within BISS,
researchers have now managed to decipher the unique structure of
auxetic natural protection and use newly-developed methods to transfer
it to the structure of foams. This makes it possible to produce
composite textiles with a protective effect not previously achieved.
Project partners in higher education research work out basics
These insights are primarily based on the scientific principles
established by research partners at universities and colleges. As part
of the project, the Department for Polymer Engineering at the
University of Bayreuth worked with the Plant Biomechanics Group
Freiburg to conduct research specifically into the creation of auxetic
structures and verify whether this concept could be transferred to
commercial foam systems made of polyurethane (PUR). Specific
structure-property relationships were also modelled to better
understand how the degree of auxetic behaviour affects the mechanical
impact behaviour of foams. The results show that conversion of the
foam network from ordinary to auxetic structures has a positive effect
on the materials’ cushioning properties. The stresses occurring during
compression of auxetic polyurethane in the material are distributed
optimally into previously unused, surrounding areas using the auxetic
effect. In this way, a larger volume of the material is involved in
the energy absorption compared to ordinary PUR foams.
The Institute of Textile Technology and Process Engineering (ITV),
which forms part of the German Institutes for Textile and Fibre
Research, has extensive knowledge in the field of textile technology
and bionics from a large number of projects. As part of the project,
ITV was intensively involved in development and design for new textile
and foam hybrids. Mesh weaving technology was modified to enable the
textiles to withstand the pressures of the foaming process and, at the
same time, allow complete foam-filling. The specially adapted mesh
fabric, combined with the foam, improved properties by nearly 25 per cent.
The Plant Biomechanics Group at the University of Freiburg has been
conducting research in the field of biomechanics and functional
morphology of plants for more than 15 years. The working group belongs
to the Baden-Württemberg Competence Network Biomimetics and has been
focusing for the past six years on biologically-inspired crash
protection, with the aim of utilizing fibre-reinforced metal foams.
Experience from this research was shared and refined in the BISS
project, allowing know-how to be successfully transferred to
biologically-inspired polymer materials and material systems.
Innovationsmanufaktur GmbH, based in Munich, supports the research
project as an associated partner. For the BISS project, which needed
to reconcile the diverse interests of industry and research, they
provided a holistic approach for project and innovation management.