Shock response mitigation of a large-scale structure by modal energy redistribution facilitated by a strongly nonlinear absorber

A lightweight geometrically nonlinear attachment, the strongly nonlinear absorber (SNA), is adopted to suppress the shock response of a linear, large-scale nine-story structure. The role of the SNA is not only to dissipate but also to redistribute the shock energy among the modes of the structure. In this study, single- and two-degree-of-freedom (SDOF and Two-DOF) SNAs are investigated. The quantitative results for shock energy redistribution indicate that with strong geometric nonlinearity, one can achieve low-to-high frequency nonlinear targeted energy transfer in this structure. Specifically, the percentages of shock energy dissipated by higher structural modes for the cases of locked SNA, SDOF SNA, and Two-DOF SNA are 0.08%, 0.43%, and 30.04%, respectively. The results indicate that the Two-DOF SNA is capable of rapidly scattering far more energy to much higher frequencies than the SDOF SNA, thereby more quickly reducing the shock response of the primary structure. The robustness of the performance of the SNAs is also studied for varying shock intensities, where the Two-DOF SNA is shown to be significantly more robust at scattering shock energy from low to high frequencies. Last, an effective damping measure is employed to verify and quantify the redistribution of the modal energies in the primary structure. The potential applications of this new passive shock mitigation method are discussed.