The tridiagonal coefficient matrix for the ＂fixed-fixed＂ spring-mass system was obtained by changing spring length. And then a new algorithm of the inverse problem was designed to construct the masses and the spring...The tridiagonal coefficient matrix for the ＂fixed-fixed＂ spring-mass system was obtained by changing spring length. And then a new algorithm of the inverse problem was designed to construct the masses and the spring constants from the natural frequencies of the ＂fixed-fixed＂ and ＂fixed-fres＂ spring-mass systems. An example was given to illustrate the results.展开更多
Metamaterial based on local resonance has excellent vibration attenuation ability in low frequency.In this research,an attempt was performed to make meta-mortar with spring-mass resonators to attenuate vibration and s...Metamaterial based on local resonance has excellent vibration attenuation ability in low frequency.In this research,an attempt was performed to make meta-mortar with spring-mass resonators to attenuate vibration and shock hazards.Single-spring-mass resonators and dual-spring-mass resonators were designed and made using lead or aluminum blocks and SWPB springs encased by PMMA(polymethyl methacrylate)or aluminum frames.These resonators were placed into mortar blocks to make metamortar specimens.Vibration attenuation effect was investigated by sweeping vibration with frequency from 50 Hz to 2000 Hz.All these meta-mortar blocks exhibit excellent vibration attenuation ability in the designed band gaps.With dual-spring-mass resonators,meta-mortar blocks have two distinct vibration attenuation bands.展开更多
Chaotic oscillations are useful in assessing the health of a structure. Hence, simple chaotic systems which can easily be realized mechanically or electro-mechanically are highly desired. We study a new pieeewise line...Chaotic oscillations are useful in assessing the health of a structure. Hence, simple chaotic systems which can easily be realized mechanically or electro-mechanically are highly desired. We study a new pieeewise linear spring-tnass system. The chaotic behaviour in this system is characterized using bifurcation diagrams and the invariant parameters of the dynamics. We also show that there exists a stochastic analogue of this system, which mimics the dynamical features of its deterministic counterpart. This allows a greater flexibility in practical designs as the chaotic oscillations are obtained either deterministically or stochastically. Also, the oscillations are low dimensional, which reduces the computational resources needed for obtaining the invariant parameters of this system.展开更多
The double degrees-of-freedom（DOFs）parallel model is adopted to analyze static vertical human-induced vibration with the finite element analysis（FEA）method.In the first-order symmetric vibration mode,the periods o...The double degrees-of-freedom（DOFs）parallel model is adopted to analyze static vertical human-induced vibration with the finite element analysis（FEA）method.In the first-order symmetric vibration mode,the periods of the spring-mass model gradually decrease with the increase in K1 and K2,but they are always greater than the period of the add-on mass model.Meanwhile,the periods of the spring-mass model decrease with the decrease in m1 and m2,but they are always greater than the period of the hollow bridge model.Since the human＇s two degrees-of-freedom vibrate in the same direction as that of the bridge mid-span,the existence of human＇s rigidity leads to the reduction in the rigidity of the spring-mass model.In the second-order symmetric vibration mode,the changes of rigidity K2 and mass m2 result in the disappearance or occurrence of some vibration modes.It can be concluded that compared with the spring-mass model,the results of the add-on mass model lean to lack of safety to the structure;besides,the DOF with a smaller ratio of mass to rigidity plays the chief role in the vibration of the structure.展开更多
对隧道、桥梁结构和沿线建筑而言,浮置板减振性能优异,但其对轨道板及其上部结构的耗能能力有限。针对此问题,将调谐质量粒子阻尼技术应用于轨道交通振动控制领域,提出一种基于调谐质量粒子阻尼器(Tuned Mass Particle Damper,TMPD)的...对隧道、桥梁结构和沿线建筑而言,浮置板减振性能优异,但其对轨道板及其上部结构的耗能能力有限。针对此问题,将调谐质量粒子阻尼技术应用于轨道交通振动控制领域,提出一种基于调谐质量粒子阻尼器(Tuned Mass Particle Damper,TMPD)的耗能型钢弹簧浮置板结构。基于调谐质量阻尼器(Tuned Mass Damper,TMD)及粒子阻尼理论,利用1:1浮置板轨道进行室内试验,通过落轴试验研究调谐质量粒子阻尼器安装前后钢弹簧浮置板轨道动力学特性。研究结果表明:TMPD能显著降低浮置板轨道在固有频率11.7 Hz附近的振动响应,浮置板加速度分频振级损失最大可达11.9 dB;安装TMPD的耗能型钢弹簧浮置板轨道从钢轨到地面的振动衰减最大可达23.6 dB,表明其具有优异的隔振效果;进行Z振级评价分析可得,耗能型钢弹簧浮置板Z振级约降低5 dB,在保证隔振效率基础上,调谐质量粒子阻尼器可提高浮置板轨道的耗能能力。展开更多
This study presents a comprehensive full dynamic model designed for simulating liquid sloshing behavior within cylindrical tank structures. The model employs a discretization approach, representing the liquid as a net...This study presents a comprehensive full dynamic model designed for simulating liquid sloshing behavior within cylindrical tank structures. The model employs a discretization approach, representing the liquid as a network of interconnected spring-damper-mass systems. Key aspects include the adaptation of liquid discretization techniques to cylindrical lateral cross-sections and the calculation of stiffness and damping coefficients. External forces, simulating various vehicle maneuvers, are also integrated into the model. The resulting system of equations is solved using Maple Software with the Runge-Kutta-Fehlberg method. This model enables accurate prediction of liquid displacement and pressure forces, offering valuable insights for tank design and fluid dynamics applications. Ongoing refinement aims to broaden its applicability across different liquid types and tank geometries.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.10271074)
文摘The tridiagonal coefficient matrix for the ＂fixed-fixed＂ spring-mass system was obtained by changing spring length. And then a new algorithm of the inverse problem was designed to construct the masses and the spring constants from the natural frequencies of the ＂fixed-fixed＂ and ＂fixed-fres＂ spring-mass systems. An example was given to illustrate the results.
基金Supports from National Natural Science Foundation of China(Grant No.12002160,and Grant No.11972184)China National Key Laboratory Foundation of Science and Technology on Materials under Shock and Impact(Grant No.6142902200203)+2 种基金Natural Science Foundation of Jiangsu Province of China(Grant No.BK20200412,BK20201286)National Defense Basic Scientific Research Program of China(TCA20030)Science and Technology Project of Jiangsu Province of China(Grant No.BE2020716)。
文摘Metamaterial based on local resonance has excellent vibration attenuation ability in low frequency.In this research,an attempt was performed to make meta-mortar with spring-mass resonators to attenuate vibration and shock hazards.Single-spring-mass resonators and dual-spring-mass resonators were designed and made using lead or aluminum blocks and SWPB springs encased by PMMA(polymethyl methacrylate)or aluminum frames.These resonators were placed into mortar blocks to make metamortar specimens.Vibration attenuation effect was investigated by sweeping vibration with frequency from 50 Hz to 2000 Hz.All these meta-mortar blocks exhibit excellent vibration attenuation ability in the designed band gaps.With dual-spring-mass resonators,meta-mortar blocks have two distinct vibration attenuation bands.
基金the Council of Scientific and Industrial Research(CSIR),New Delhi for Financial Support through a Senior Research Fellowship(SRF)
文摘Chaotic oscillations are useful in assessing the health of a structure. Hence, simple chaotic systems which can easily be realized mechanically or electro-mechanically are highly desired. We study a new pieeewise linear spring-tnass system. The chaotic behaviour in this system is characterized using bifurcation diagrams and the invariant parameters of the dynamics. We also show that there exists a stochastic analogue of this system, which mimics the dynamical features of its deterministic counterpart. This allows a greater flexibility in practical designs as the chaotic oscillations are obtained either deterministically or stochastically. Also, the oscillations are low dimensional, which reduces the computational resources needed for obtaining the invariant parameters of this system.
文摘The double degrees-of-freedom（DOFs）parallel model is adopted to analyze static vertical human-induced vibration with the finite element analysis（FEA）method.In the first-order symmetric vibration mode,the periods of the spring-mass model gradually decrease with the increase in K1 and K2,but they are always greater than the period of the add-on mass model.Meanwhile,the periods of the spring-mass model decrease with the decrease in m1 and m2,but they are always greater than the period of the hollow bridge model.Since the human＇s two degrees-of-freedom vibrate in the same direction as that of the bridge mid-span,the existence of human＇s rigidity leads to the reduction in the rigidity of the spring-mass model.In the second-order symmetric vibration mode,the changes of rigidity K2 and mass m2 result in the disappearance or occurrence of some vibration modes.It can be concluded that compared with the spring-mass model,the results of the add-on mass model lean to lack of safety to the structure;besides,the DOF with a smaller ratio of mass to rigidity plays the chief role in the vibration of the structure.
文摘对隧道、桥梁结构和沿线建筑而言,浮置板减振性能优异,但其对轨道板及其上部结构的耗能能力有限。针对此问题,将调谐质量粒子阻尼技术应用于轨道交通振动控制领域,提出一种基于调谐质量粒子阻尼器(Tuned Mass Particle Damper,TMPD)的耗能型钢弹簧浮置板结构。基于调谐质量阻尼器(Tuned Mass Damper,TMD)及粒子阻尼理论,利用1:1浮置板轨道进行室内试验,通过落轴试验研究调谐质量粒子阻尼器安装前后钢弹簧浮置板轨道动力学特性。研究结果表明:TMPD能显著降低浮置板轨道在固有频率11.7 Hz附近的振动响应,浮置板加速度分频振级损失最大可达11.9 dB;安装TMPD的耗能型钢弹簧浮置板轨道从钢轨到地面的振动衰减最大可达23.6 dB,表明其具有优异的隔振效果;进行Z振级评价分析可得,耗能型钢弹簧浮置板Z振级约降低5 dB,在保证隔振效率基础上,调谐质量粒子阻尼器可提高浮置板轨道的耗能能力。
文摘This study presents a comprehensive full dynamic model designed for simulating liquid sloshing behavior within cylindrical tank structures. The model employs a discretization approach, representing the liquid as a network of interconnected spring-damper-mass systems. Key aspects include the adaptation of liquid discretization techniques to cylindrical lateral cross-sections and the calculation of stiffness and damping coefficients. External forces, simulating various vehicle maneuvers, are also integrated into the model. The resulting system of equations is solved using Maple Software with the Runge-Kutta-Fehlberg method. This model enables accurate prediction of liquid displacement and pressure forces, offering valuable insights for tank design and fluid dynamics applications. Ongoing refinement aims to broaden its applicability across different liquid types and tank geometries.
