针对随机激励下振动系统的减振问题,提出了考虑摩擦与非线性阻尼的混联Ⅱ型惯容非线性能量阱(nonlinear energy sink,简称NES),建立了含新型NES主系统的动力学控制方程。首先,采用蒙特卡洛数值方法,研究了非线性刚度对减振性能的影响,...针对随机激励下振动系统的减振问题,提出了考虑摩擦与非线性阻尼的混联Ⅱ型惯容非线性能量阱(nonlinear energy sink,简称NES),建立了含新型NES主系统的动力学控制方程。首先,采用蒙特卡洛数值方法,研究了非线性刚度对减振性能的影响,当非线性刚度比κ_(21)逐渐增大时,主结构和混联Ⅱ型惯容NES的位移概率密度函数出现了双峰变为单峰,以及速度概率密度函数由单峰变为双峰的随机跳跃现象。主结构的位移概率密度函数对非线性刚度κ_(22)的敏感性比κ_(21)更高,κ_(22)最佳取值区间为200~1 000。其次,研究了噪声强度、阻尼比和惯质比对减振性能的影响,当噪声强度小于0.1或惯质比μ在0.1左右时,惯容NES的减振效果较好。虽然线性阻尼比λ_(1)和非线性阻尼比λ_(21)、λ_(22)增大会导致主结构和混联Ⅱ型惯容NES的概率密度函数出现分岔不稳定现象,但增大非线性阻尼比有助于改善惯容NES的减振性能。最后,采用差分进化法对惯容NES的参数进行了优化。本研究可为受随机激励的振动系统减振研究提供技术参考。展开更多
地下粮仓具有充分利用地下空间和抵抗外部干扰能力强等优点。为研究地下粮仓结构与土场相互作用的动力学特征,以装配式地下粮仓结构中钢桩为研究对象,利用非线性能量阱(nonlinear energy sink,NES)理论,将地下粮仓周围简化为非线性Wink...地下粮仓具有充分利用地下空间和抵抗外部干扰能力强等优点。为研究地下粮仓结构与土场相互作用的动力学特征,以装配式地下粮仓结构中钢桩为研究对象,利用非线性能量阱(nonlinear energy sink,NES)理论,将地下粮仓周围简化为非线性Winkler地基,钢桩简化为简支的Euler-Bernoulli梁。利用Hamilton原理,建立梁-土系统的运动方程;引入地基反力系数,描述土体的非线性刚度;利用增量谐波平衡法,求得运动方程的半解析解,并与数值解对比验证。与不考虑NES效应的结果对比,分析阻尼、质量比和地基反力系数等参数对结构在简谐激励下动力响应的影响,分析不同参数条件下土场对结构振动响应的抑制效果。研究表明:选取合理的阻尼、质量比和地基反力系数等参数时,弹性土体能在宽频带范围内减小结构稳态振动能量,显著降低结构共振能量峰和响应幅值;在经分析所得到的最优参数条件下,振动能量衰减率达99.39%。研究成果进一步阐释了土-结构相互作用效应的减振吸能作用,并为基于NES理论的地下粮仓减振设计提供了理论依据。展开更多
为拓宽非线性能量阱(nonlinear energy sink,NES)的频率变化范围,基于负刚度原理,通过预压弹簧构造负刚度系统,设计水平向的负刚度NES减震器。利用ABAQUS有限元软件对负刚度NES减震器进行数值模拟,在导杆无摩擦且弹簧不发生侧向屈曲的...为拓宽非线性能量阱(nonlinear energy sink,NES)的频率变化范围,基于负刚度原理,通过预压弹簧构造负刚度系统,设计水平向的负刚度NES减震器。利用ABAQUS有限元软件对负刚度NES减震器进行数值模拟,在导杆无摩擦且弹簧不发生侧向屈曲的状态下,分析弹簧行程长宽比、预压缩量、刚度和阻尼比对负刚度NES减震器抗震性能的影响。研究结果表明:在固定弹簧行程长宽比的条件下,增加弹簧的预压缩量,可提高减震器的抗震性能;在固定弹簧预压缩量的条件下,随着弹簧行程长宽比的增大,减震器的承载力逐渐减小,抗震性能下降;弹簧刚度和阻尼比的增加可显著增大减震器的承载力,提高抗震性能。研究结果为负刚度NES减震器的工程应用提供参考。展开更多
The post-collisional Cenozoic basic volcanic rocks in NE Turkey show temporal variations in whole-rock lithophile element and highly siderophile element(HSE)systematics that are mainly associated with the nature of su...The post-collisional Cenozoic basic volcanic rocks in NE Turkey show temporal variations in whole-rock lithophile element and highly siderophile element(HSE)systematics that are mainly associated with the nature of sub-continental lithospheric mantle(SCLM)sources and parental melt generation.So far,the traditional whole-rock lithophile geochemical data of these basic volcanic rocks have provided important constraints on the nature of SCLM sources.Integrated lithophile element and HSE geochemical data of these basic volcanic rocks also reveal the heterogeneity of the SCLM source,which is principally related to variable metasomatism resulting from previous subduction(s)and post-collisional mantle-crust interactions in an extensional setting.Lithophile element geochemical features suggest that the parental magmas have derived from metasomatized spinel-to garnet-bearing SCLM sources for Eocene and Miocene basic volcanic rocks with subduction signatures whereas originated from spinel-to garnet-bearing SCLM sources for Mio-Pliocene and Plio-Quaternary basaltic volcanic rocks without the subduction signature.Lithophile element and HSE geo-chemistry also reveal that Eocene and Miocene basic vol-canic rocks were affected by more pronounced crustal contamination than the basaltic volcanic rocks of Mio-Pliocene and Quaternary.Furthermore,the integrated lithophile element and HSE compositions of these basic volcanic rocks,together with the regional asymmetric lithospheric delamination model,reveal that the compositional variation(especially due to metasomatism)was significant temporally in the heterogeneity of the SCLM sources from which parental magmas formed during the Cenozoic era.展开更多
A broadband adaptive vibration control strategy with high reliability and flexible versatility is proposed.The high vibration damping performance of nonlinear energy sink(NES)has attracted attention.However,targeted e...A broadband adaptive vibration control strategy with high reliability and flexible versatility is proposed.The high vibration damping performance of nonlinear energy sink(NES)has attracted attention.However,targeted energy transfer may cause severe vibration of NES.Besides,it is difficult to realize pure nonlinear stiffness without the linear part.As a result,the reliability of NES is not high.The low reliability of NES has hindered its application in engineering.In addition,the performance of NES depends on its mass ratio of the primary system,and NES lacks versatility for different vibration systems.Therefore,this paper proposes the concept of NES cell.The advantages of the adaptive vibration control of NES are applied to cellular NES.By applying a large number of NES cells in parallel,the reliability of NES and its versatility to complex vibration structures are improved.An elastic beam is used as the primary vibration structure,and a limited NES is used as the cell.The relationship between the vibration suppression effect of NES cells and the number of NES cell is studied.In addition,the effect of the distribution of NES cells on the multi-mode resonance suppression of the beam is also studied.In summary,the mode of the primary structure can be efficiently controlled by a large number of lightweight NES cell.Therefore,the lightweight NES cell is flexible for vibration control of complex structures.In addition,it improves the reliability of NES applications.Therefore,the distributed application of NES cells proposed in this paper is a valuable vibration suppression strategy.展开更多
为提高控制装置的减震性能及减小附加阻尼器的质量,基于非对称非线性能量阱(nonlinear energy sink,NES)提出一种附加惯容器的新型控制装置——非对称惯容NES。根据非对称惯容NES系统的工作原理推导出运动方程;在脉冲型荷载作用下进行...为提高控制装置的减震性能及减小附加阻尼器的质量,基于非对称非线性能量阱(nonlinear energy sink,NES)提出一种附加惯容器的新型控制装置——非对称惯容NES。根据非对称惯容NES系统的工作原理推导出运动方程;在脉冲型荷载作用下进行控制参数数值优化,分析非对称惯容NES的能量鲁棒性和频率鲁棒性。分析地震作用下结构与控制装置响应,研究主体结构刚度变化前后的控制性能。应用数值小波变换对体系的地震响应时程进行功率谱分析,从能量的角度研究控制装置的减振机理。研究结果表明,非对称惯容NES具有极强的能量鲁棒性和频率鲁棒性,在地震作用过程中能有效减小顶层加速度峰值且所需行程更小,能在更广频域内与主体结构发生共振,因而其减震效率更高。非对称惯容NES减震控制性能与已有的非对称NES相当甚至更优,并能够减小40%阻尼器质量,在实际应用中具有更广阔的前景。展开更多
文摘针对随机激励下振动系统的减振问题,提出了考虑摩擦与非线性阻尼的混联Ⅱ型惯容非线性能量阱(nonlinear energy sink,简称NES),建立了含新型NES主系统的动力学控制方程。首先,采用蒙特卡洛数值方法,研究了非线性刚度对减振性能的影响,当非线性刚度比κ_(21)逐渐增大时,主结构和混联Ⅱ型惯容NES的位移概率密度函数出现了双峰变为单峰,以及速度概率密度函数由单峰变为双峰的随机跳跃现象。主结构的位移概率密度函数对非线性刚度κ_(22)的敏感性比κ_(21)更高,κ_(22)最佳取值区间为200~1 000。其次,研究了噪声强度、阻尼比和惯质比对减振性能的影响,当噪声强度小于0.1或惯质比μ在0.1左右时,惯容NES的减振效果较好。虽然线性阻尼比λ_(1)和非线性阻尼比λ_(21)、λ_(22)增大会导致主结构和混联Ⅱ型惯容NES的概率密度函数出现分岔不稳定现象,但增大非线性阻尼比有助于改善惯容NES的减振性能。最后,采用差分进化法对惯容NES的参数进行了优化。本研究可为受随机激励的振动系统减振研究提供技术参考。
文摘地下粮仓具有充分利用地下空间和抵抗外部干扰能力强等优点。为研究地下粮仓结构与土场相互作用的动力学特征,以装配式地下粮仓结构中钢桩为研究对象,利用非线性能量阱(nonlinear energy sink,NES)理论,将地下粮仓周围简化为非线性Winkler地基,钢桩简化为简支的Euler-Bernoulli梁。利用Hamilton原理,建立梁-土系统的运动方程;引入地基反力系数,描述土体的非线性刚度;利用增量谐波平衡法,求得运动方程的半解析解,并与数值解对比验证。与不考虑NES效应的结果对比,分析阻尼、质量比和地基反力系数等参数对结构在简谐激励下动力响应的影响,分析不同参数条件下土场对结构振动响应的抑制效果。研究表明:选取合理的阻尼、质量比和地基反力系数等参数时,弹性土体能在宽频带范围内减小结构稳态振动能量,显著降低结构共振能量峰和响应幅值;在经分析所得到的最优参数条件下,振动能量衰减率达99.39%。研究成果进一步阐释了土-结构相互作用效应的减振吸能作用,并为基于NES理论的地下粮仓减振设计提供了理论依据。
文摘为拓宽非线性能量阱(nonlinear energy sink,NES)的频率变化范围,基于负刚度原理,通过预压弹簧构造负刚度系统,设计水平向的负刚度NES减震器。利用ABAQUS有限元软件对负刚度NES减震器进行数值模拟,在导杆无摩擦且弹簧不发生侧向屈曲的状态下,分析弹簧行程长宽比、预压缩量、刚度和阻尼比对负刚度NES减震器抗震性能的影响。研究结果表明:在固定弹簧行程长宽比的条件下,增加弹簧的预压缩量,可提高减震器的抗震性能;在固定弹簧预压缩量的条件下,随着弹簧行程长宽比的增大,减震器的承载力逐渐减小,抗震性能下降;弹簧刚度和阻尼比的增加可显著增大减震器的承载力,提高抗震性能。研究结果为负刚度NES减震器的工程应用提供参考。
文摘The post-collisional Cenozoic basic volcanic rocks in NE Turkey show temporal variations in whole-rock lithophile element and highly siderophile element(HSE)systematics that are mainly associated with the nature of sub-continental lithospheric mantle(SCLM)sources and parental melt generation.So far,the traditional whole-rock lithophile geochemical data of these basic volcanic rocks have provided important constraints on the nature of SCLM sources.Integrated lithophile element and HSE geochemical data of these basic volcanic rocks also reveal the heterogeneity of the SCLM source,which is principally related to variable metasomatism resulting from previous subduction(s)and post-collisional mantle-crust interactions in an extensional setting.Lithophile element geochemical features suggest that the parental magmas have derived from metasomatized spinel-to garnet-bearing SCLM sources for Eocene and Miocene basic volcanic rocks with subduction signatures whereas originated from spinel-to garnet-bearing SCLM sources for Mio-Pliocene and Plio-Quaternary basaltic volcanic rocks without the subduction signature.Lithophile element and HSE geo-chemistry also reveal that Eocene and Miocene basic vol-canic rocks were affected by more pronounced crustal contamination than the basaltic volcanic rocks of Mio-Pliocene and Quaternary.Furthermore,the integrated lithophile element and HSE compositions of these basic volcanic rocks,together with the regional asymmetric lithospheric delamination model,reveal that the compositional variation(especially due to metasomatism)was significant temporally in the heterogeneity of the SCLM sources from which parental magmas formed during the Cenozoic era.
基金Project supported by the National Science Fund for Distinguished Young Scholars of China (No.12025204)the Shanghai Municipal Education Commission of China (No.2019-01-07-00-09-E00018)。
文摘A broadband adaptive vibration control strategy with high reliability and flexible versatility is proposed.The high vibration damping performance of nonlinear energy sink(NES)has attracted attention.However,targeted energy transfer may cause severe vibration of NES.Besides,it is difficult to realize pure nonlinear stiffness without the linear part.As a result,the reliability of NES is not high.The low reliability of NES has hindered its application in engineering.In addition,the performance of NES depends on its mass ratio of the primary system,and NES lacks versatility for different vibration systems.Therefore,this paper proposes the concept of NES cell.The advantages of the adaptive vibration control of NES are applied to cellular NES.By applying a large number of NES cells in parallel,the reliability of NES and its versatility to complex vibration structures are improved.An elastic beam is used as the primary vibration structure,and a limited NES is used as the cell.The relationship between the vibration suppression effect of NES cells and the number of NES cell is studied.In addition,the effect of the distribution of NES cells on the multi-mode resonance suppression of the beam is also studied.In summary,the mode of the primary structure can be efficiently controlled by a large number of lightweight NES cell.Therefore,the lightweight NES cell is flexible for vibration control of complex structures.In addition,it improves the reliability of NES applications.Therefore,the distributed application of NES cells proposed in this paper is a valuable vibration suppression strategy.
文摘为提高控制装置的减震性能及减小附加阻尼器的质量,基于非对称非线性能量阱(nonlinear energy sink,NES)提出一种附加惯容器的新型控制装置——非对称惯容NES。根据非对称惯容NES系统的工作原理推导出运动方程;在脉冲型荷载作用下进行控制参数数值优化,分析非对称惯容NES的能量鲁棒性和频率鲁棒性。分析地震作用下结构与控制装置响应,研究主体结构刚度变化前后的控制性能。应用数值小波变换对体系的地震响应时程进行功率谱分析,从能量的角度研究控制装置的减振机理。研究结果表明,非对称惯容NES具有极强的能量鲁棒性和频率鲁棒性,在地震作用过程中能有效减小顶层加速度峰值且所需行程更小,能在更广频域内与主体结构发生共振,因而其减震效率更高。非对称惯容NES减震控制性能与已有的非对称NES相当甚至更优,并能够减小40%阻尼器质量,在实际应用中具有更广阔的前景。
