利用强非线性减振器的模态能量再分配缓解大型结构的冲击响应

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

采用一种轻型几何非线性附件,强非线性减振器(SNA),以抑制线性大型九层结构的冲击响应.SNA的作用不仅是耗散能量,而且重新分配结构模态之间的冲击能量.本文研究单自由度(SDOF)和双自由度(Two-DOF)的SNAs.冲击能量再分配的定量结果表明,在强几何非线性的情况下,这种结构可以实现从低频到高频的非线性单向能量传递.具体而言,在锁定SNA、单自由度SNA和双自由度SNA的情况下,较高结构模态耗散的冲击能量百分比分别为0.08%,0.43%和30.04%.结果表明,与单自由度SNA相比,双自由度SNA能够将更多的能量快速散射到更高的频域,从而更快地降低主结构的冲击响应.还研究了在不同冲击强度下SNA性能的鲁棒性,其中双自由度SNA在从低频到高频散射冲击能量时表现出更强的鲁棒性.最后,采用等效阻尼技术来验证和量化主结构中模态能量的重新分布,并讨论这种新型被动减震方法的潜在应用.

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.