Impact dampers are usually used to suppress single mode resonance. The goal of this paper is to clarify the difference when the impact damper suppresses the resonances of different modes. A cantilever beam equipped wi...Impact dampers are usually used to suppress single mode resonance. The goal of this paper is to clarify the difference when the impact damper suppresses the resonances of different modes. A cantilever beam equipped with the impact damper is modeled. The elastic contact of the ball and the cantilever beam is described by using the Hertz contact model. The viscous damper between the ball and the cantilever beam is modeled to consume the vibrational energy of the cantilever beam. A piecewise ordinary differential-partial differential equation of the cantilever beam is established, including equations with and without the impact damper. The vibration responses of the cantilever beam with and without the impact damper are numerically calculated. The effects of the impact absorber parameters on the vibration reduction are examined. The results show that multiple resonance peaks of the cantilever beam can be effectively suppressed by the impact damper. Specifically, all resonance amplitudes can be reduced by a larger weight ball. Moreover, the impacting gap is very effective in suppressing the vibration of the cantilever beam. More importantly, there is an optimal impacting gap for each resonance mode of the cantilever beam, but the optimal gap for each mode is different.展开更多
A good mechanical model of magnetorheological damper (MRD) is essential to predict the shock isolation performance of MRD in numerical simulation. But at present, the mechanical models of MRD were all derived from the...A good mechanical model of magnetorheological damper (MRD) is essential to predict the shock isolation performance of MRD in numerical simulation. But at present, the mechanical models of MRD were all derived from the experiment subjected to harmonic vibration loads. In this paper, a commercial MRD (type RD-1005-3) manufactured by Lord Corporation was studied ex-perimentally in order to investigate its isolation performance under the impact loads. A new me-chanical model of MRD was proposed according to the data obtained by impact test. A good agreement between the numerical results and test data was observed, which showed that the model was good to simulate the dynamic properties of MRD under impact loads. It is also demon-strated that MRD can improve the acceleration and displacement response of the structure obvi-ously under impact loads.展开更多
This paper investigates the characteristics of reduction of the lateral vibration by use of a Tuned Mass Damper(TMD) for offshore jacket platforms under impact loading. Unlike traditional analysis, the present analysi...This paper investigates the characteristics of reduction of the lateral vibration by use of a Tuned Mass Damper(TMD) for offshore jacket platforms under impact loading. Unlike traditional analysis, the present analysis focnses on theenergy concept of TMD/structure systems. In this study, a time domain is taken. The platform is modeled as a simplifiedsingle-degree-of-freedom (SDOF) system by extraction of the first vibration mode of the structure and the excited force isassumed to be impact loading. The energy dissipation and energy transmission of the structure-TMD system are studied.Finally, an optimized TMD design for the modeled platform is demonstrated based on a new type of cost function - maxi-mum dissipated energy by TMD. Results indicate that TMD control is effective in reducing the standard deviation of thedeck motion but less effective in reducing the maximum response under impact loading.展开更多
To mitigate the degree of damage to passengers caused by automobile collisions, a friction damper was built and used in experimental tests to test its effectiveness in impact energy attenuation. The study revealed tha...To mitigate the degree of damage to passengers caused by automobile collisions, a friction damper was built and used in experimental tests to test its effectiveness in impact energy attenuation. The study revealed that energy absorption capacity of a bumper can be improved with the addition of a friction damper. The results revealed that the addition of the friction damper to an automobile bumper to give a bumper-damper system could attenuate about 32.5 % more energy than with the bumper alone. It can be concluded that the effectiveness of automobile bumpers to withstand impact of vehicles by absorbing the kinetic energy from the impact can be improved with the use of a passive friction damper. That is, a passive friction damper system could be used to attenuate more road vehicle impact energy in collisions.展开更多
针对液压阻尼器特性,研制了一种同时满足其动静态性能测试的试验台,解决了该试验台面临的一系列关键技术问题。从节能的角度,采用小泵站大蓄能器组的形式,解决了动静态试验对流量要求差别巨大的矛盾;在回油路上设置蓄能器组解决了大流...针对液压阻尼器特性,研制了一种同时满足其动静态性能测试的试验台,解决了该试验台面临的一系列关键技术问题。从节能的角度,采用小泵站大蓄能器组的形式,解决了动静态试验对流量要求差别巨大的矛盾;在回油路上设置蓄能器组解决了大流量对回油管路和低压元件的冲击问题;采用液压夹紧方式,使得试验空间的调节方便可靠;采用上下位机的控制模式,同时满足了数据采集速度和控制界面友好的要求。该试验台的最大输出动态力为1 000 kN,频率范围为0.01～33 H z。试验表明,该试验台较好地满足了设计要求,完全满足阻尼器的试验需求。展开更多
基金the National Natural Science Foundation of China(No.11772181)the Program of Shanghai Municipal Education Commission(No.2019-01-07-00-09-E0018)the Key Research Projects of Shanghai Science and Technology Commission(No.18010500100)。
文摘Impact dampers are usually used to suppress single mode resonance. The goal of this paper is to clarify the difference when the impact damper suppresses the resonances of different modes. A cantilever beam equipped with the impact damper is modeled. The elastic contact of the ball and the cantilever beam is described by using the Hertz contact model. The viscous damper between the ball and the cantilever beam is modeled to consume the vibrational energy of the cantilever beam. A piecewise ordinary differential-partial differential equation of the cantilever beam is established, including equations with and without the impact damper. The vibration responses of the cantilever beam with and without the impact damper are numerically calculated. The effects of the impact absorber parameters on the vibration reduction are examined. The results show that multiple resonance peaks of the cantilever beam can be effectively suppressed by the impact damper. Specifically, all resonance amplitudes can be reduced by a larger weight ball. Moreover, the impacting gap is very effective in suppressing the vibration of the cantilever beam. More importantly, there is an optimal impacting gap for each resonance mode of the cantilever beam, but the optimal gap for each mode is different.
基金Supported by National Natural Science Foundation of China (No.50638030,50525825)the National Science and Technology SupportProgram (No.2006BAJ13B02)
文摘A good mechanical model of magnetorheological damper (MRD) is essential to predict the shock isolation performance of MRD in numerical simulation. But at present, the mechanical models of MRD were all derived from the experiment subjected to harmonic vibration loads. In this paper, a commercial MRD (type RD-1005-3) manufactured by Lord Corporation was studied ex-perimentally in order to investigate its isolation performance under the impact loads. A new me-chanical model of MRD was proposed according to the data obtained by impact test. A good agreement between the numerical results and test data was observed, which showed that the model was good to simulate the dynamic properties of MRD under impact loads. It is also demon-strated that MRD can improve the acceleration and displacement response of the structure obvi-ously under impact loads.
基金by the National Natural Science Foundation of China(Grant No.50179014)
文摘This paper investigates the characteristics of reduction of the lateral vibration by use of a Tuned Mass Damper(TMD) for offshore jacket platforms under impact loading. Unlike traditional analysis, the present analysis focnses on theenergy concept of TMD/structure systems. In this study, a time domain is taken. The platform is modeled as a simplifiedsingle-degree-of-freedom (SDOF) system by extraction of the first vibration mode of the structure and the excited force isassumed to be impact loading. The energy dissipation and energy transmission of the structure-TMD system are studied.Finally, an optimized TMD design for the modeled platform is demonstrated based on a new type of cost function - maxi-mum dissipated energy by TMD. Results indicate that TMD control is effective in reducing the standard deviation of thedeck motion but less effective in reducing the maximum response under impact loading.
文摘To mitigate the degree of damage to passengers caused by automobile collisions, a friction damper was built and used in experimental tests to test its effectiveness in impact energy attenuation. The study revealed that energy absorption capacity of a bumper can be improved with the addition of a friction damper. The results revealed that the addition of the friction damper to an automobile bumper to give a bumper-damper system could attenuate about 32.5 % more energy than with the bumper alone. It can be concluded that the effectiveness of automobile bumpers to withstand impact of vehicles by absorbing the kinetic energy from the impact can be improved with the use of a passive friction damper. That is, a passive friction damper system could be used to attenuate more road vehicle impact energy in collisions.
文摘针对液压阻尼器特性,研制了一种同时满足其动静态性能测试的试验台,解决了该试验台面临的一系列关键技术问题。从节能的角度,采用小泵站大蓄能器组的形式,解决了动静态试验对流量要求差别巨大的矛盾;在回油路上设置蓄能器组解决了大流量对回油管路和低压元件的冲击问题;采用液压夹紧方式,使得试验空间的调节方便可靠;采用上下位机的控制模式,同时满足了数据采集速度和控制界面友好的要求。该试验台的最大输出动态力为1 000 kN,频率范围为0.01～33 H z。试验表明,该试验台较好地满足了设计要求,完全满足阻尼器的试验需求。
