The paper moves from a technological process developed in previous works to produce chiral honeycombs made of thin composite laminates. Such approach is applied in this work to manufacture the morphing ribs for a variable camber wing-box. The specifications for such components are obtained by developing a finite element model of a demonstrator, which is designed taking into account aeroelastic performances, structural, and technological issues. In the first part of the paper, the design of such a demonstrator is presented and the role of composite chiral ribs with auxetic behavior is outlined. Production, testing, and numerical studies of manufacturing trials are performed to assess the technological process applied to small-sized chiral units made of different materials, to investigate their mechanical properties, and to validate a numerical approach for design and analysis. A complete chiral composite rib is then produced and tests are carried out to verify the overall structural response and to validate the numerical approach

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Composite materials utilizing natural fibers are becoming more popular and have a broad range of usage in the industry. Natural fibers come from nature and they have many advantages which are low cost, easily available and environmentally friendly. Some natural fibers are obtained from plants while others could be obtained from trees. Commonly used natural fibers are jute, flax, sisal, bamboo and ramie. In order to produce composite materials from natural fibers, both thermoset and thermoplastic resins can be used. In this experimental study, epoxy resin was combined with jute and flax woven fibers to obtain hybrid composites. Firstly, fibers were treated with a solution containing 5 % alkaline to improve the mechanical properties of the fibers. Two different chemicals were used to improve the fire resistance of the fibers namely ammonium sulfate and diammonium phosphate. Two different solutions were prepared for this purpose; a solution containing 20% of ammonium sulfate was prepared for the treatment of jute fiber and another solution containing 10% of diammonium phosphate was prepared for the treatment of flax fiber. The epoxy was applied to both samples by hand layup method and the curing was carried out by using the hot press. The hardness, thickness and mass of the produced samples were measured and a fire experiment was carried out. Several parameters such as flammability, heat distribution and temperature of the sample surfaces were investigated. Low flammability, low heat distribution and low temperature properties were observed on the surfaces of the samples which were chemically treated by using ammonium sulfate and diammonium phosphate.

Auxetic chiral topologies can be applied to design composite aeronautical morphing structures with the capability of progressive shape variations. Progresses towards the development of such composite chiral structures require fulfillment of aeroelastic constraints, adequate strength properties and feasible technological routes. Moving from a configuration identified by aeroelastic optimization, design methods and technological processes are set up and applied by Airoldi et al. (pp. http://doi.wiley.com/10.1002/pssb.201451689) to accomplish such goals. The figure shows a chiral wing‐box demonstrator designed according to the chiral sail concept, which can lead to improve the stabilization effect of aerodynamic surfaces. Laminates made of carbon‐fibre reinforced plastic layers are produced. They are assembled by exploiting elastomeric tooling techniques and, finally, a chiral composite rib is manufactured and tested. In the background, a finite element study is shown for the production of chiral composite networks with enhanced strength properties, by using a simplified technological approach. The relevant numerical and experimental results are reported by Airoldi et al. on pp. http://doi.wiley.com/10.1002/pssb.201584263.