The pseudo-viscous frictional energy dissipator（PVFED） is a new energy dissipator. This dissipator can be widely used in engineering for not only the friction is in direct ratio to velocity, but also the problem of ...The pseudo-viscous frictional energy dissipator（PVFED） is a new energy dissipator. This dissipator can be widely used in engineering for not only the friction is in direct ratio to velocity, but also the problem of viscous energy dissipator mucilage easily leaked has been overcome. The problem of how to get response of the PVFED sys- tem need to be solved before this dissipator can be used widely in engineering. The response calculation methods of the PVFED system on sina load was researched. Wilson-θ,Newmark-β and a precise integration algorithm was used separately to solve the system response and the calculation result in a different time step was compared. It was found from comparison that three calculation results were almost equivalent in a small time step. Calculation precision of Newmark-β and Wilson-θ was reduced and high calculation precision of a precise integration algorithm was kept in a large time step. The results show that it is an effective way to solve the response of a PVFED system by a precise integration method.展开更多
This paper presents the results from unidirectional shaking table tests of two reduced scale steel models of a building frame, with one and two floors, respectively. These frames incorporate friction dissipators at ev...This paper presents the results from unidirectional shaking table tests of two reduced scale steel models of a building frame, with one and two floors, respectively. These frames incorporate friction dissipators at every floor. The inputs are sine-dwells and artificial and registered earthquakes. This study is part of a larger research project aiming to assess the seismic efficiency of friction dissipators by means of an integrated numerical and experimental approach. Inside this framework, the main objectives of these experiments are to： （i） collect a wide range of results to calibrate a numerical model derived within the project, （ii） clarify some of the most controversial issues about friction dissipators （including behavior for inputs containing pulses, capacity to reduce resonance peaks, introduction of high frequencies in the response, and self- generated eccentricities）, （iii） better understand their dynamic behavior, （iv） provide insight on the feasibility and reliability of using simple friction dissipators for seismic protection of building structures and （v） characterize the hysteretic behavior of these devices. Most of these objectives are satisfactorily reached and relevant conclusions are stated.展开更多
This study investigates the effect of contact surface curvatures on the friction response under varying tangential loadings using a finite element(FE)model.The results showed that the geometry of the surface influence...This study investigates the effect of contact surface curvatures on the friction response under varying tangential loadings using a finite element(FE)model.The results showed that the geometry of the surface influences the contact force at the interface and reduces the friction effect through an unsteady distribution of the contact force.The relationship between the friction effect,excitation,and contact surface shape was also examined,revealing a linear inverse relationship between the friction and curvature.The findings provide a comprehensive understanding of the frictional interactions between elastic bodies and highlight the role of curvature as a design parameter for regulating the friction effect.展开更多
About 30%of the world's primary energy consumption is in friction.The economic losses caused by friction energy dissipation and wear account for about 2%-7%of its gross domestic product(GDP)for different countries...About 30%of the world's primary energy consumption is in friction.The economic losses caused by friction energy dissipation and wear account for about 2%-7%of its gross domestic product(GDP)for different countries every year.The key to reducing energy consumption is to control the way of energy dissipation in the friction process.However,due to many various factors affecting friction and the lack of efficient detection methods,the energy dissipation mechanism in friction is still a challenging problem.Here,we firstly introduce the classical microscopic mechanism of friction energy dissipation,including phonon dissipation,electron dissipation,and non-contact friction energy dissipation.Then,we attempt to summarize the ultrafast friction energy dissipation and introduce the high-resolution friction energy dissipation detection system,since the origin of friction energy dissipation is essentially related to the ultrafast dynamics of excited electrons and phonons.Finally,the application of friction energy dissipation in representative high-end equipment is discussed,and the potential economic saving is predicted.展开更多
Flexible microporous metal rubber (FMP-MR) is a high-damping material that dissipates energy by dry friction through internal spiral metal wires in contact with each other. However, the FMP-MR energy dissipation mecha...Flexible microporous metal rubber (FMP-MR) is a high-damping material that dissipates energy by dry friction through internal spiral metal wires in contact with each other. However, the FMP-MR energy dissipation mechanism is not fully understood owing to its disordered grid interpenetrating structure. In this work, computer-aided preparation technology is used to accurately reconstruct the complex spiral network structure of FMP-MR multipoint random contact, and a cell group model with an energy dissipation mechanism is proposed to obtain the dynamic energy distribution of the contact friction in both space and time dimensions. By judging the effective contact point, a global displacement ablation phenomenon of hooked staggered porous materials is induced. The macro- and micro-equivalent frictions are introduced to effectively explain the characteristics of the strong energy dissipation in FMP-MR under fretting excitation. A real and effective damping hysteresis constitutive model is then constructed to dynamically capture the mapping relationship between the complex nonlinear topological structure effect of the materials and spatial random contact dry friction in real time. The results indicate that the contact behavior between turns of the FMP-MR wire follows a clear quasi-Gaussian distribution under an external load, forcing the topological results to change. The energy dissipation of the materials revealed peak energy consumption lagging behind the loading limit for a certain distance, which can be determined by the effective contact point and contact dry friction slip. The consistency between the quasi-static compression tests and constitutive curves of the model was quantitatively verified through residual analysis. The data demonstrated the differential behavior of the FMP-MR meso-structure to follow a phased growth law during loading with different action mechanisms in the guiding, main growth, and relaxation stages of the energy consumption displacement curve. In summary, these findings provide an acceptable theoretical basis for the damping energy consumption mechanism and lifetime prediction of FMP-MR.展开更多
为解决传统自复位支撑耗能能力不足而位移放大阻尼器缺少复位能力的问题,基于桥式放大工作机理提出了一种具有位移放大功能的摩擦自复位支撑(self-centering displacement amplification function brace,SC-DAFB)。该文介绍了SC-DAFB基...为解决传统自复位支撑耗能能力不足而位移放大阻尼器缺少复位能力的问题,基于桥式放大工作机理提出了一种具有位移放大功能的摩擦自复位支撑(self-centering displacement amplification function brace,SC-DAFB)。该文介绍了SC-DAFB基本构造、工作机理,阐述了SC-DAFB耗能系统的位移及SC-DAFB受力放大机理,推导出了SC-DAFB各加载阶段的恢复力计算公式,通过对6组不同工况的SC-DAFB进行低周往复加载试验,得到并对比分析了SC-DAFB的承载能力、滞回曲线、耗能性能及残余位移等关键力学性能指标。结果表明:SC-DAFB滞回曲线饱满,具有典型的旗帜型特征,但存在一定程度的非对称特性;减小初始放大角度能够有效提升SC-DAFB的承载能力和耗能性能,当复位比为1.3时,与无位移放大SC-DAFB相比,30°初始放大角度下SC-DAFB屈服荷载和最大荷载分别提高47.6%和29.4%,但SC-DAFB残余变形略有增加;理论计算与试验得到的SC-DAFB滞回曲线对比结果表明,建立的分段式理论恢复力模型与试验结果吻合较好,验证了理论恢复力模型的准确性。展开更多
Based on energy dissipation and structural control principle, a new structural configuration, called the megasub controlled structure （MSCS） with friction damped braces （FDBs）, is first presented. Meanwhile, to ca...Based on energy dissipation and structural control principle, a new structural configuration, called the megasub controlled structure （MSCS） with friction damped braces （FDBs）, is first presented. Meanwhile, to calculate the damping coefficient in the slipping state a new analytical method is proposed. The damping characteristics of one-storey friction damped braced frame （FDBF） are investigated, and the influence of the structural parameters on the energy dissipation and the practical engineering design are discussed. The nonlinear dynamic equations and the analytical model of the MSCS with FDBs are established. Three building structures with different structural configurations, which were designed with reference to the conventional mega-sub structures such as used in Tokyo City Hall, are comparatively investigated. The results illustrate that the structure presented in the paper has excellent dynamic properties and satisfactory control effectiveness.展开更多
文摘The pseudo-viscous frictional energy dissipator（PVFED） is a new energy dissipator. This dissipator can be widely used in engineering for not only the friction is in direct ratio to velocity, but also the problem of viscous energy dissipator mucilage easily leaked has been overcome. The problem of how to get response of the PVFED sys- tem need to be solved before this dissipator can be used widely in engineering. The response calculation methods of the PVFED system on sina load was researched. Wilson-θ,Newmark-β and a precise integration algorithm was used separately to solve the system response and the calculation result in a different time step was compared. It was found from comparison that three calculation results were almost equivalent in a small time step. Calculation precision of Newmark-β and Wilson-θ was reduced and high calculation precision of a precise integration algorithm was kept in a large time step. The results show that it is an effective way to solve the response of a PVFED system by a precise integration method.
基金Supported by Spanish Government,Grant CGL2008-00869/BTE
文摘This paper presents the results from unidirectional shaking table tests of two reduced scale steel models of a building frame, with one and two floors, respectively. These frames incorporate friction dissipators at every floor. The inputs are sine-dwells and artificial and registered earthquakes. This study is part of a larger research project aiming to assess the seismic efficiency of friction dissipators by means of an integrated numerical and experimental approach. Inside this framework, the main objectives of these experiments are to： （i） collect a wide range of results to calibrate a numerical model derived within the project, （ii） clarify some of the most controversial issues about friction dissipators （including behavior for inputs containing pulses, capacity to reduce resonance peaks, introduction of high frequencies in the response, and self- generated eccentricities）, （iii） better understand their dynamic behavior, （iv） provide insight on the feasibility and reliability of using simple friction dissipators for seismic protection of building structures and （v） characterize the hysteretic behavior of these devices. Most of these objectives are satisfactorily reached and relevant conclusions are stated.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.NRF-2021R1F1A1052123).
文摘This study investigates the effect of contact surface curvatures on the friction response under varying tangential loadings using a finite element(FE)model.The results showed that the geometry of the surface influences the contact force at the interface and reduces the friction effect through an unsteady distribution of the contact force.The relationship between the friction effect,excitation,and contact surface shape was also examined,revealing a linear inverse relationship between the friction and curvature.The findings provide a comprehensive understanding of the frictional interactions between elastic bodies and highlight the role of curvature as a design parameter for regulating the friction effect.
基金supported by the National Natural Science Foundation of China(Nos.52075284,52105195,51527901,and 11890672)the Postdoctoral Research Foundation of China(Nos.2020M680528 and BX2021151).
文摘About 30%of the world's primary energy consumption is in friction.The economic losses caused by friction energy dissipation and wear account for about 2%-7%of its gross domestic product(GDP)for different countries every year.The key to reducing energy consumption is to control the way of energy dissipation in the friction process.However,due to many various factors affecting friction and the lack of efficient detection methods,the energy dissipation mechanism in friction is still a challenging problem.Here,we firstly introduce the classical microscopic mechanism of friction energy dissipation,including phonon dissipation,electron dissipation,and non-contact friction energy dissipation.Then,we attempt to summarize the ultrafast friction energy dissipation and introduce the high-resolution friction energy dissipation detection system,since the origin of friction energy dissipation is essentially related to the ultrafast dynamics of excited electrons and phonons.Finally,the application of friction energy dissipation in representative high-end equipment is discussed,and the potential economic saving is predicted.
基金the National Natural Science Foundation of China(Grant Nos.52175162,51805086,and 51975123)the Natural Science Foundation of Fujian Province(Grant No.2019J01210)Health education joint project of Fujian Province(Grant No.2019-WJ-01).
文摘Flexible microporous metal rubber (FMP-MR) is a high-damping material that dissipates energy by dry friction through internal spiral metal wires in contact with each other. However, the FMP-MR energy dissipation mechanism is not fully understood owing to its disordered grid interpenetrating structure. In this work, computer-aided preparation technology is used to accurately reconstruct the complex spiral network structure of FMP-MR multipoint random contact, and a cell group model with an energy dissipation mechanism is proposed to obtain the dynamic energy distribution of the contact friction in both space and time dimensions. By judging the effective contact point, a global displacement ablation phenomenon of hooked staggered porous materials is induced. The macro- and micro-equivalent frictions are introduced to effectively explain the characteristics of the strong energy dissipation in FMP-MR under fretting excitation. A real and effective damping hysteresis constitutive model is then constructed to dynamically capture the mapping relationship between the complex nonlinear topological structure effect of the materials and spatial random contact dry friction in real time. The results indicate that the contact behavior between turns of the FMP-MR wire follows a clear quasi-Gaussian distribution under an external load, forcing the topological results to change. The energy dissipation of the materials revealed peak energy consumption lagging behind the loading limit for a certain distance, which can be determined by the effective contact point and contact dry friction slip. The consistency between the quasi-static compression tests and constitutive curves of the model was quantitatively verified through residual analysis. The data demonstrated the differential behavior of the FMP-MR meso-structure to follow a phased growth law during loading with different action mechanisms in the guiding, main growth, and relaxation stages of the energy consumption displacement curve. In summary, these findings provide an acceptable theoretical basis for the damping energy consumption mechanism and lifetime prediction of FMP-MR.
文摘为解决传统自复位支撑耗能能力不足而位移放大阻尼器缺少复位能力的问题,基于桥式放大工作机理提出了一种具有位移放大功能的摩擦自复位支撑(self-centering displacement amplification function brace,SC-DAFB)。该文介绍了SC-DAFB基本构造、工作机理,阐述了SC-DAFB耗能系统的位移及SC-DAFB受力放大机理,推导出了SC-DAFB各加载阶段的恢复力计算公式,通过对6组不同工况的SC-DAFB进行低周往复加载试验,得到并对比分析了SC-DAFB的承载能力、滞回曲线、耗能性能及残余位移等关键力学性能指标。结果表明:SC-DAFB滞回曲线饱满,具有典型的旗帜型特征,但存在一定程度的非对称特性;减小初始放大角度能够有效提升SC-DAFB的承载能力和耗能性能,当复位比为1.3时,与无位移放大SC-DAFB相比,30°初始放大角度下SC-DAFB屈服荷载和最大荷载分别提高47.6%和29.4%,但SC-DAFB残余变形略有增加;理论计算与试验得到的SC-DAFB滞回曲线对比结果表明,建立的分段式理论恢复力模型与试验结果吻合较好,验证了理论恢复力模型的准确性。
基金Science and Technology Fund of NWPU Under Grant No. M450211 Seed Fund of NWPU Under Grant No. Z200729
文摘Based on energy dissipation and structural control principle, a new structural configuration, called the megasub controlled structure （MSCS） with friction damped braces （FDBs）, is first presented. Meanwhile, to calculate the damping coefficient in the slipping state a new analytical method is proposed. The damping characteristics of one-storey friction damped braced frame （FDBF） are investigated, and the influence of the structural parameters on the energy dissipation and the practical engineering design are discussed. The nonlinear dynamic equations and the analytical model of the MSCS with FDBs are established. Three building structures with different structural configurations, which were designed with reference to the conventional mega-sub structures such as used in Tokyo City Hall, are comparatively investigated. The results illustrate that the structure presented in the paper has excellent dynamic properties and satisfactory control effectiveness.
