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In this paper, the electrical conductivity and electromagnetic shielding effectiveness of two bio-composites are studied by experimental testing and numerical models. Two monolithic composites with partly bio-based content were manufactured. The first bio-composite is made of a carbon fiber fabric prepreg and a partly bio-based (rosin) epoxy resin (CF/Rosin). The second bio-composite is a combination of prepregs of carbon fiber fabric/epoxy resin and flax fiber fabric/epoxy resin (CF-Flax/Epoxy). A single line infusion process was used prior to the curing step in the autoclave. Both variants are exemplary for the possibility of introducing bio-based materials in high performance CFRP. In-plane and out-of-plane electrical conductivity tests were conducted according to Airbus standards AITM2 0064 and AITM2 0065, respectively. Electromagnetic shielding effectiveness tests were conducted based on the standard ASTM D 4935-10. Materials were prepared at the German Aerospace Center (DLR), while characterization tests were conducted at the University of Patras. In addition to the tests, numerical models of representative volume elements were developed, using the DIGIMAT software, to predict the electrical conductivity of the two bio-composites. The preliminary numerical results show a good agreement with the experimental results.Electromagnetic (EM) penetration of aircrafts mainly comes from lightning effects. On the other hand, lightning discharges do not necessarily have to hit the aircraft structure directly to create EM fields. Intracloud discharges, for example, might produce intense high-frequency radiation [9]. Additionally, to the lightning effects, an electromagnetically disturbed environment for the aircraft is developed from the infrastructure of all communication, entertainment and surveillance. EM radiation penetrates the aircraft from outboard ground-based transmitters for navigation, communication, radar surveillance from other aircrafts or satellite propagation, as well as from onboard generated interferences appearing by the carried onboard communication and entertainment equipment. Whereas a metallic aircraft fuselage principally counters these EM fields like a faraday cage-through its high electrical conductivity is able to deflect and absorb the radiation and provides an EM shield-a composite fuselage is not able to counter EM fields without enhancement [10,11].Studies have shown that there are several health effects caused by of electromagnetic fields. Sensitive individuals with electromagnetic field exposure from various sources experience ill health symptoms [12]. This phenomenon is called EHS (electromagnetic hypersensitivity), and according to WHO, 1%-3% of the population are affected by it [13,14]. Moreover, when passengers are exposed to the EM waves, the network of veins in high-risk organs, such as eyes, might be affected. This is due to heat build-up in the eyes by the EM waves, which could not be easily dissipated. Studies have shown that the EMF (electromagnetic fields) exposures have sign...

In the present work, the mechanical, thermal and electrical properties of CNT/polymer nanocomposites are computed using numerical and analytical models as functions of material parameters (CNT aspect ratio, CNT waviness, presence of the interphase) and processing factors (CNT volume fraction, formation of agglomerates and the number and arrangement of CNTs in the agglomerates). The computation is performed using representative unit cells (RUCs) of CNT agglomerates. The RUCs are solved numerically using the FE method and analytically using the Mori-Tanaka method. At the same time, homogenization is applied in the RUCs. The results from the parametric study reveal that the considered parameters and factors govern the reinforcement effectiveness and, under specific combinations, might counterbalance the multifunctionality of nanocomposites.

For this present paper, we performed a life-cycle analysis and an evaluation of the mechanical properties of an epichlorohydrin/cardanol adhesive in a neat and a nano-filled form. Six different potentials and the cost of the adhesives were derived and compared with those of a commercial epoxy resin. Overall, the neat adhesive was found to be more environmentally friendly and to have a lower production cost. However, the addition of carbon nanotubes increased both the environmental footprint and the cost. The evaluation with regards to the mechanical properties was performed through a comparison of bulk properties and joint properties with the respective average values of commonly used structural and nonstructural adhesives from the literature. It was found that for all properties except for the Young’s modulus the novel adhesive had values greater than the average values of the cosmetic adhesives and for most properties it had values close to the average values of the structural adhesives. Moreover, the presence of the carbon nanotubes enhanced the mechanical properties of the adhesive except for the tensile strength.