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  • Engineering of a foam-filled auxetic absorber for localized impact [Elektronski vir]
    Di Mauro, Sebastiano ...
    In this work the design of an impact energy absorber, based on an auxetic hexachiral frame filled with foam, was developed and was focused on the identification of the geometrical parameters for the ... fulfilment of the requirements in a pre-defined application scenario. Some of the outcomes of two research in the literature were the starting point of the present work: specifically, the importance of the combination of materials used to build the auxetic structure and the beneficial effects of the interaction between an auxetic frame and foam, which leads to substantial increments of absorbed energy per unit volume and mass. Using materials with high elongation at break, such as an elastomeric material, deserved investigation since it could guarantee the preservation of the auxetic property for the whole duration of the localized impact, as the early breakage of chiral ligaments or chiral nodes, which induce the loss of the auxetic property, could be avoided. All these aspects were considered in the engineering of an absorber concept in a specific crash scenario, represented by the impact between a Vulnerable Road User and the bumper of a vehicle. The regulation EEVC/WG17 EURO Phase2 was taken as a reference in order to perform a realistic study of the energy absorber. Moreover, among different polymeric materials, a thermoplastic polyurethane with micronized waste-tire-rubber was used to build the auxetic frame. It exhibits a large strain at failure and can be 3D-printed to obtain auxetic topologies, and involves the use of recycled material. Dynamic drop-weight impacts were conducted on sample structures and compared with the numerical model. Initial numerical-experimental correlation showed that the FE model had some differences with the experimental results, and this was probably due to the preliminary numerical material model developed and used for the hexachiral frame, but the use of elastomeric material was promising. Despite the differences in its calibration, the FE model was used to build a database and to train two metamodels. Finally, an optimization procedure based on a genetic algorithm was presented. Two optimal solutions of foam-filled hexachiral structure were found, considering the penetration and level of force as targets, and using the geometrical parameters of the auxetic frame as design variables. Results indicated that the optimized auxetic structures were able to absorb the impact energy by mitigating the force on the simplified VRU below the desired level, with a limited penetration.
    Vir: Proceedings of the 15th International Conference on Shock & Impact Loads on Structures [Elektronski vir] : 12-13 June, 2025, Gothenburg, Sweden : Chalmers (Str. 34-44)
    Vrsta gradiva - prispevek na konferenci ; neleposlovje za odrasle
    Leto - 2025
    Jezik - angleški
    COBISS.SI-ID - 241804035

    Povezava(-e):

    https://research.chalmers.se/publication/547397/file/547397_Fulltext.pdf

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