A novel variable damper using an adjustable energy harvesting structure is proposed for semi-active vibration systems. The fluid flowing in a hydraulic cylinder is employed to drive an electromagnetic generator for ha...A novel variable damper using an adjustable energy harvesting structure is proposed for semi-active vibration systems. The fluid flowing in a hydraulic cylinder is employed to drive an electromagnetic generator for harvesting vibration energy, which on the other hand, leads to a damping effect of the hydraulic damper. To make the damping force variable, an adjustable resistor is adopted to tune the capability of energy harvesting. The present approach is validated by both theoretical analysis and experimental evaluation. When connected with different resistance loads, the prototype damper has different equivalent damping coefficients ranging from 3. 987 × 104 to 2. 488 × 105 N· s/m. The results show that the damping force of the damper is variable in response to the adjustable load for the vibration energy harvesting.展开更多
In order to improve the seismic performance of adjacent buildings,two types of tuned inerter damper(TID)damping systems for adjacent buildings are proposed,which are composed of springs,inerter devices and dampers in ...In order to improve the seismic performance of adjacent buildings,two types of tuned inerter damper(TID)damping systems for adjacent buildings are proposed,which are composed of springs,inerter devices and dampers in serial or in parallel.The dynamic equations of TID adjacent building damping systems were derived,and the H2 norm criterion was used to optimize and adjust them,so that the system had the optimum damping performance under white noise random excitation.Taking TID frequency ratio and damping ratio as optimization parameters,the optimum analytical solutions of the displacement frequency response of the undamped structure under white noise excitation were obtained.The results showed that compared with the classic TMD,TID could obtain a better damping effect in the adjacent buildings.Comparing the TIDs composed of serial or parallel,it was found that the parallel TIDs had more significant advantages in controlling the peak displacement frequency response,while the H2 norm of the displacement frequency response of the damping system under the coupling of serial TID was smaller.Taking the adjacent building composed of two ten-story frame structures as an example,the displacement and energy collection time history analysis of the adjacent building coupled with the optimum design parameter TIDs were carried out.It was found that TID had a better damping effect in the full-time range compared with the classic TMD.This paper also studied the potential power of TID in adjacent buildings,which can be converted into available power resources during earthquakes.展开更多
Ferrofluids are a type of nanometer-scale functional material with fluidity and superparamagnetism.They are composed of ferromagnetic particles,surfactants,and base liquids.The main characteristics of ferrofluids incl...Ferrofluids are a type of nanometer-scale functional material with fluidity and superparamagnetism.They are composed of ferromagnetic particles,surfactants,and base liquids.The main characteristics of ferrofluids include magnetization,the magnetoviscous effect,and levitation characteristics.There are many mature commercial ferrofluid damping applications based on these characteristics that are widely used in numerous fields.Furthermore,some ferrofluid damping studies such as those related to vibration energy harvesters and biomedical devices are still in the laboratory stage.This review paper summarizes typical ferrofluid dampers and energy harvesting systems from the 1960s to the present,including ferrofluid viscous dampers,ferrofluid inertia dampers,tuned magnetic fluid dampers(TMFDs),and vibration energy harvesters.In particular,it focuses on TMFDs and vibration energy harvesters because they have been the hottest research topics in the ferrofluid damping field in recent years.This review also proposes a novel magnetic fluid damper that achieves energy conversion and improves the efficiency of vibration attenuation.Finally,we discuss the potential challenges and development of ferrofluid damping in future research.展开更多
Tuned mass dampers（TMDs）are one of the most widely used devices to mitigate vibrations in structures.Usually,in conventional TMDs,viscous dampers convert the energy of vibration into heat.A new type of TMDs,called r...Tuned mass dampers（TMDs）are one of the most widely used devices to mitigate vibrations in structures.Usually,in conventional TMDs,viscous dampers convert the energy of vibration into heat.A new type of TMDs,called regenerative TMDs,has展开更多
利用电磁换能器代替传统型调谐质量阻尼器中的黏性阻尼,形成一种具有结构减震与能量收集双重功能的电磁调谐质量阻尼器(electromagnetic tuned mass damper,EMTMD)。通过分析电磁换能器的动力学模型,建立了电磁调谐质量阻尼器的力学模...利用电磁换能器代替传统型调谐质量阻尼器中的黏性阻尼,形成一种具有结构减震与能量收集双重功能的电磁调谐质量阻尼器(electromagnetic tuned mass damper,EMTMD)。通过分析电磁换能器的动力学模型,建立了电磁调谐质量阻尼器的力学模型。将电磁调谐质量阻尼器与单自由度结构相结合,建立耦合结构受地震作用时的动力学模型。基于H2优化理论,即以主结构位移均方根值最小为目标函数,对EMTMD进行参数优化,得到EMTMD的结构频率比、电磁阻尼比和机电耦合系数的参数优化解析解。通过频域和时域两种方法数值仿真分析了EMTMD对结构减震与能量收集的性能。结果表明,在最优状态下,EMTMD对结构位移、加速度峰值和均方根的减振性能略优于经典TMD,且其能量收集的平均功率高达约4.05×105 W。展开更多
基金The National Natural Science Foundation of China(No.51375517)the Natural Science Foundation of CQ CSTC(No.2012JJJQ70001)the Project of Chongqing Innovation Team in University(No.KJTD201313)
文摘A novel variable damper using an adjustable energy harvesting structure is proposed for semi-active vibration systems. The fluid flowing in a hydraulic cylinder is employed to drive an electromagnetic generator for harvesting vibration energy, which on the other hand, leads to a damping effect of the hydraulic damper. To make the damping force variable, an adjustable resistor is adopted to tune the capability of energy harvesting. The present approach is validated by both theoretical analysis and experimental evaluation. When connected with different resistance loads, the prototype damper has different equivalent damping coefficients ranging from 3. 987 × 104 to 2. 488 × 105 N· s/m. The results show that the damping force of the damper is variable in response to the adjustable load for the vibration energy harvesting.
基金This research was funded by the Natural Science Research Project of Higher Education Institutions in Anhui Province(Grant No.2022AH040045)the Anhui Provincial Natural Science Foundation(Grant No.2008085QE245)the Project of Science and Technology Plan of Department of Housing and Urban-Rural Development of Anhui Province(Grant No.2021-YF22).
文摘In order to improve the seismic performance of adjacent buildings,two types of tuned inerter damper(TID)damping systems for adjacent buildings are proposed,which are composed of springs,inerter devices and dampers in serial or in parallel.The dynamic equations of TID adjacent building damping systems were derived,and the H2 norm criterion was used to optimize and adjust them,so that the system had the optimum damping performance under white noise random excitation.Taking TID frequency ratio and damping ratio as optimization parameters,the optimum analytical solutions of the displacement frequency response of the undamped structure under white noise excitation were obtained.The results showed that compared with the classic TMD,TID could obtain a better damping effect in the adjacent buildings.Comparing the TIDs composed of serial or parallel,it was found that the parallel TIDs had more significant advantages in controlling the peak displacement frequency response,while the H2 norm of the displacement frequency response of the damping system under the coupling of serial TID was smaller.Taking the adjacent building composed of two ten-story frame structures as an example,the displacement and energy collection time history analysis of the adjacent building coupled with the optimum design parameter TIDs were carried out.It was found that TID had a better damping effect in the full-time range compared with the classic TMD.This paper also studied the potential power of TID in adjacent buildings,which can be converted into available power resources during earthquakes.
基金the National Natural Science Foundation of China(Grant Nos.51735006,51927810,and U1837206)Beijing Municipal Natural Science Foundation(Grant No.3182013)。
文摘Ferrofluids are a type of nanometer-scale functional material with fluidity and superparamagnetism.They are composed of ferromagnetic particles,surfactants,and base liquids.The main characteristics of ferrofluids include magnetization,the magnetoviscous effect,and levitation characteristics.There are many mature commercial ferrofluid damping applications based on these characteristics that are widely used in numerous fields.Furthermore,some ferrofluid damping studies such as those related to vibration energy harvesters and biomedical devices are still in the laboratory stage.This review paper summarizes typical ferrofluid dampers and energy harvesting systems from the 1960s to the present,including ferrofluid viscous dampers,ferrofluid inertia dampers,tuned magnetic fluid dampers(TMFDs),and vibration energy harvesters.In particular,it focuses on TMFDs and vibration energy harvesters because they have been the hottest research topics in the ferrofluid damping field in recent years.This review also proposes a novel magnetic fluid damper that achieves energy conversion and improves the efficiency of vibration attenuation.Finally,we discuss the potential challenges and development of ferrofluid damping in future research.
基金supported by the National Natural Science Foundation of China(Grant Nos.51422809&51578314)Tsinghua University Initiative Scientific Research Program(Grant No.2014z22067)
文摘Tuned mass dampers（TMDs）are one of the most widely used devices to mitigate vibrations in structures.Usually,in conventional TMDs,viscous dampers convert the energy of vibration into heat.A new type of TMDs,called regenerative TMDs,has
文摘利用电磁换能器代替传统型调谐质量阻尼器中的黏性阻尼,形成一种具有结构减震与能量收集双重功能的电磁调谐质量阻尼器(electromagnetic tuned mass damper,EMTMD)。通过分析电磁换能器的动力学模型,建立了电磁调谐质量阻尼器的力学模型。将电磁调谐质量阻尼器与单自由度结构相结合,建立耦合结构受地震作用时的动力学模型。基于H2优化理论,即以主结构位移均方根值最小为目标函数,对EMTMD进行参数优化,得到EMTMD的结构频率比、电磁阻尼比和机电耦合系数的参数优化解析解。通过频域和时域两种方法数值仿真分析了EMTMD对结构减震与能量收集的性能。结果表明,在最优状态下,EMTMD对结构位移、加速度峰值和均方根的减振性能略优于经典TMD,且其能量收集的平均功率高达约4.05×105 W。
