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G E N E R A T I V E COMPOSITE FIBER Generative manufacturing of composite components allows us to place each fiber individually - and thus optimized on forces - and produce space frame structures. The impressive example of a natural creature from the deep sea points out the potential of space frame structures made with composite fiber. The Venus’ Flower Basket is a sponge and has a space frame structure made of silicates. The silicates are very similar to the industrially processed glass fiber. The enormous stability, which is achieved with little material, makes this sponge quite impressive. His skeleton is considered to be unbreakable. At a length of 28 cm and a diameter of 3.5 cm it weighs approximately 5 g.
Benjamin Würkner • Hochschule für Gestaltung Offenbach am Main 2015 • Betreut von Prof. Dr. Markus Holzbach • Institut für Materialdesign IMD • Seite 1/5
(A) Photograph (B) Fragment, Scale bar, 5 mm. (C) SEM, Scale bar, 100 mm. (D) SEM, Scale bar, 20 mm. (E) SEM, Scale bar, 25 mm. Abb.1: Joanna Aizenberg, James C. Weaver, Monica S. Thanawala, Vikram C. Sundar, Daniel E. Morse, Peter Fratzl: Skeleton of Euplectella sp.: Structural Hierarchy from the Nanoscale to the Macroscale. In: SCIENCE (Magazine), August 2005
Fig. 1. Structural analysis of the mineralized skeletal system of Euplectella sp. (A) Photograph of the entire skeleton, showing cylindrical glass cage. Scale bar, 1 cm. (B) Fragment of the cage structure showing the square-grid lattice of vertical and horizontal struts with diagonal elements arranged in a chessboard manner. Orthogonal ridges on the cylinder surface are indicated by arrows. Scale bar, 5 mm. (C) Scanning electron micrograph (SEM) showing that each strut (enclosed by a bracket) is composed of bundled multiple spicules (the arrow indicates the long axis of the skeletal lattice). Scale bar, 100 mm. (D) SEM of a fractured and partially HF-etched (25) single beam revealing its ceramic fiber-composite structure. Scale
bar, 20 mm. (E) SEM of the HF-etched (25) junction area showing that the lattice is cemented with laminated silica layers. Scale bar, 25 mm. (F) Contrast-enhanced SEM image of a cross section through one of the spicular struts, revealing that they are composed of a wide range of different-sized spicules surrounded by a laminated silica matrix. Scale bar, 10 mm. (G) SEM of a cross section through a typical spicule in a strut, showing its characteristic laminated architecture. Scale bar, 5 mm. (H) SEM of a fractured spicule, revealing an organic interlayer. Scale bar, 1 mm. (I) Bleaching of biosilica surface revealing its consolidated nanoparticulate nature (25). Scale bar, 500 nm.
arranged in a cylindrical fashion around a exposed to ocean currents and supports the where K1C is the fracture toughness of the central proteinaceous filament and are sepliving portion of the sponge responsible for glass, sth f is the theoretical strength of the arated from one another by organic interfiltering and metabolite trapping (23, 24). The defect-free material, and h* is a characteristic layers (Fig. 1H). Etching of spicule layers characteristic sizes and construction mechlength (for typical ceramic materials, this and the surrounding cement showed that at anisms of the Euplectella sp. skeletal syslength is on the order of 10 to 30 nm) (26). the nanoscale the fundamental construction tem are expected to be fine-tuned for these For defects smaller than h*, there is no stress unit consists of consolidated hydrated silica functions. concentration at the defect, and the strength of nanoparticles (50 to 200 nm in diameter) At the macroscale, the cylindrical structure the material is equal to its defect-free value (Fig. 1I) (17–19, 22). The different levels of is reinforced by external ridges that extend (26). Because the mineral particles in bone, structural complexity are schematically shown perpendicular to the surface of the cylinder for example, are thinner than this value, these in Fig. 2. In the following discussion, each and spiral the cage at an angle of 45- (shown particles should be insensitive to defects and hierarchical level is examined from the meby arrows in Fig. 1B). The pitch of the extherefore flaw tolerant. This argument does chanical perspective. ternal ridges decreases from the basal to the not apply, however, to biologically produced The first level is biologically produced top portion of the cage. The surface of the glass, because individual silica nanospheres glass composed of consolidated silica nanocylinder consists of a regular square lattice range from 50 nm to 200 nm in diameter and spheres formed around a protein filament (Fig. composed of a series of cemented vertical and thus are larger than h*. 2A). Glass as a building material suffers horizontal struts (Fig. 1B), each consisting of The intrinsically low strength of the glass primarily from its brittleness. This means that bundled spicules aligned parallel to one is balanced at the next structural level. The is limited mostly by surface another 1C), with diagonal elements P.itsC.:strength spicule as a whole can be regarded as a lamAbb. 2: (Fig. Mineralien und Fossilienhandlung http://www.ebay.de/itm/Euplectella-aspergillum-Giesskannendefects where the applied stresses concentrate. positioned in every second square cell (Fig. inated composite (27) in which the organic schwamm-Schwamm-/121750819838?nma=true&si=IhDVuMq0zbZbF9uXbbJrcI6Lllo%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557, A scratch in the surface of glass readily in1B). Cross-sectional analyses of these beams interlayers act as crack stoppers (Fig. 2B). If 16.03.2016 duces fracture. If we consider that surface at the micron scale reveal that they are a point load is applied to the surface, one defects in the biosilica may be induced by composed of collections of silica spicules (5 may expect that the damage will be restricted external point loads, either biologically or to 50 mm in diameter) embedded in a layered to the outermost layers (28). A larger number otherwise applied, a scratched plain glass silica matrix (Fig. 1, D to F). The higher of individual glass layers should protect the
FIBER SPIDER
G E N E R A T I V E COMPOSITE FIBER The structure of the silicate skeleton consists of hierarchical organized material -from nano-scale to macro scale. It starts with the formation of the fiber and goes on with the fiber bundle up to the formation of the macro-scale space frame structure. This space frame structure consists of struts that are arranged in a rectangular grid, supported by diagonal cross braces. Thus the sponge can ideally withstand tensile and shear stresses. With generative design methods a space frame structure like that, composed of 3D printed glass fiber composite, was created.Fiber Spider is a parametrically programmed machine, that uses an extruder, gravity and magnetic pull to apply glass fibers in the shape of catenaries, creating a space frame. Each fiber is individually placed in space and optimized on forces by programming and automation.
Benjamin Würkner • Hochschule für Gestaltung Offenbach am Main 2015 • Betreut von Prof. Dr. Markus Holzbach • Institut für Materialdesign IMD • Seite 2/5
FIBER SPIDER
G E N E R A T I V E COMPOSITE FIBER A custom fiber extruder with three axes X, Y and Z makes it possible to generate the fiber networks in conjunction with the information of the digital calculations and form findings. The magnetically manipulated catenaries of the lightweight composite connect to force optimization strategies of lightweight constructions in architecture. Architects have used catenary models to find force optimized forms to achieve a reduction of material and weight in their constructions.
Benjamin Würkner • Hochschule für Gestaltung Offenbach am Main 2015 • Betreut von Prof. Dr. Markus Holzbach • Institut für Materialdesign IMD • Seite 3/5
FIBER SPIDER
G E N E R A T I V E COMPOSITE FIBER Additive Manufacturing becomes more and more relevant for industry. The additive manufacturing process is going to be an important part for a customizable and resource-efficient industrial production.For fiber composites, the additive manufacturing is still little or not developed. But the method offers the possibility to reduce the presently high proportion of manual labor in the manufacture of fiber composite components and also the potential to optimize the component part in terms of weight and resource-saving. Unlike the conventional processing, the fiber is arranged in a three-dimensionally extended structure. The concept is, to produce lightweight components with maximum stability and minimal weight on an additive method.
Benjamin Würkner • Hochschule für Gestaltung Offenbach am Main 2015 • Betreut von Prof. Dr. Markus Holzbach • Institut für Materialdesign IMD • Seite 4/5
FIBER SPIDER
G E N E R A T I V E COMPOSITE FIBER Graduation project 2015 Benjamin Würkner Department Design University of Art and Design Offenbach am Main Prof. Dr. Markus Holzbach Institute for Materialdesign IMD
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Benjamin Würkner • Hochschule für Gestaltung Offenbach am Main 2015 • Betreut von Prof. Dr. Markus Holzbach • Institut für Materialdesign IMD • Seite 5/5