How does negative Poisson’s ratio of foam filler affect crashworthiness?

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• Consideration of Poisson’s Ratio effects of metallic foam filler on structural crashworthiness allowed optimizing filler properties for different foam-filled square, circular and conic tubes.

As an effective candidate for enhancing energy absorption, a range of foam materials have gained considerable popularity, in which the density, Young’s modulus and plasticity of foam materials are considered critical to crashworthiness. Relatively speaking, less attention has been paid to the roles played by the Poisson’s ratio of foam or cellular materials. More importantly, the interaction between different Poisson’s ratios and thin-walled structures has been a critical yet under-studied issue. This paper aims to explore the effects of negative, zero and positive Poisson’s ratio of auxetic foams, ranging from −1 to 0.5, on structural crashworthiness and seek optimal design for different foam-filled square, circular and conic tubes. In this study the specific energy absorption (SEA) and mean crushing force (MCF) are taken as the objective functions by using mathematical regression analysis. The sequential quadratic programming (SQP) and the Non-dominated Sorting Genetic Algorithm II (NSGA-II) are employed for single and multiobjective design of foam-filled tubes with different Poisson’s ratios, respectively. The optimal Poisson’s ratio is obtained for these three different types of foam-filled tubes. By comparison we found that the crashworthiness of foam filled conic tube is the best, followed by circular and then squared tubes. The study provides new insights into material selection and design with a more favorable Poisson’s ratio for crashworthiness.

Impact loading condition and cross-sections of squared, circular and conic foam filled thin-wall tubes with Poisson’s Ratio −0.99 < ν < 0.49.Figure optionsDownload as PowerPoint slide