A new type of linear ultrasonic motor with two degrees of freedom (DOF) motion is presented. The concept of the new typical motor is based on the combination of a longitudinal and two bending modes. The construction a...A new type of linear ultrasonic motor with two degrees of freedom (DOF) motion is presented. The concept of the new typical motor is based on the combination of a longitudinal and two bending modes. The construction and the operational principle of motor are described, and the elliptical motion of the driving point of the actuator is proved. Meanwhile, a prototype linear motor is designed by using the finite element method (FEM) and is constructed for experiments. The vibration modes are tested with the laser doppler vibrometer (PSV-300F), and the experimental results prove that the design requirements on the mode shape of the actuator and nature frequency are satisfied. The test run of the motor indicates that the operational principle of the motor and the design results are correct, and the output properties are also tested.展开更多
With the development of deepwater oil and gas exploration, Steel Catenary Risers(SCRs) become preferred risers for resource production, import and export. Vortex induced vibration(VIV) is the key problem encountered i...With the development of deepwater oil and gas exploration, Steel Catenary Risers(SCRs) become preferred risers for resource production, import and export. Vortex induced vibration(VIV) is the key problem encountered in the design of SCRs. In this study, a new model, the rigid swing model, is proposed based on the consideration of large curvature of SCRs. The sag bend of SCRs is assumed as a rigid swing system around the axis from the hanging point to the touch down point(TDP) in the model. The torque, produced by the lift force and the swing vector, provides the driving torque for the swing system, and the weight of SCRs provides the restoring torque. The simulated response of rigid swing is coupled with bending vibration, and then the coupling VIV model of SCRs is studied in consideration of bending vibration and rigid motion. The calculated results indicate that the rigid swing has a magnitude equal to that of bending vibration, and the rigid motion affects the dynamic response of SCRs and can not be neglected in the VIV analysis.展开更多
The theory of dynamic vibration absorber(DVA)was applied to restrain the vibration of carbody for high-speed electric multiple unit(EMU).The carbody was modeled as an Euler-Bernoulli beam with the equipment mounted on...The theory of dynamic vibration absorber(DVA)was applied to restrain the vibration of carbody for high-speed electric multiple unit(EMU).The carbody was modeled as an Euler-Bernoulli beam with the equipment mounted on the chassis regarded as a DVA.Suspension parameters of the equipment were optimized based on the modal analysis of the beam and parameter optimization of the DVA.Vertical motion equations of the carbody and equipment were derived to study the effect of the suspension parameters on the vibration of carbody,which included the suspension frequency,damping ratio,mounting position and mass.Then a 3D rigid-flexible coupled vehicle system dynamics model was built to simulate the response of carbody and equipment to track excitation.The results show that the equipment mounted on the carbody chassis can be regarded as a DVA to reduce the flexible vibration of carbody,and the optimum suspension frequency can be calculated theoretically with the first-order vertical bending mode of carbody considered.Heavy equipment should be mounted to the carbody center as close as possible to obtain a significant vibration reduction,while light equipment has quite limited contribution to that.Also,a laboratory test was conducted on the full-scale test rig which shows a good agreement with the theoretical analysis and dynamic simulations.The faster the vehicle runs,the more significant are the advantages of the elastic suspension.展开更多
文摘A new type of linear ultrasonic motor with two degrees of freedom (DOF) motion is presented. The concept of the new typical motor is based on the combination of a longitudinal and two bending modes. The construction and the operational principle of motor are described, and the elliptical motion of the driving point of the actuator is proved. Meanwhile, a prototype linear motor is designed by using the finite element method (FEM) and is constructed for experiments. The vibration modes are tested with the laser doppler vibrometer (PSV-300F), and the experimental results prove that the design requirements on the mode shape of the actuator and nature frequency are satisfied. The test run of the motor indicates that the operational principle of the motor and the design results are correct, and the output properties are also tested.
基金funded by the National Natural Science Foundation of China(51079136,51179179,51239008)
文摘With the development of deepwater oil and gas exploration, Steel Catenary Risers(SCRs) become preferred risers for resource production, import and export. Vortex induced vibration(VIV) is the key problem encountered in the design of SCRs. In this study, a new model, the rigid swing model, is proposed based on the consideration of large curvature of SCRs. The sag bend of SCRs is assumed as a rigid swing system around the axis from the hanging point to the touch down point(TDP) in the model. The torque, produced by the lift force and the swing vector, provides the driving torque for the swing system, and the weight of SCRs provides the restoring torque. The simulated response of rigid swing is coupled with bending vibration, and then the coupling VIV model of SCRs is studied in consideration of bending vibration and rigid motion. The calculated results indicate that the rigid swing has a magnitude equal to that of bending vibration, and the rigid motion affects the dynamic response of SCRs and can not be neglected in the VIV analysis.
基金supported by the National Science and Technology Support Program of China(2009BAG12A01-A02)the New Century Excellent Talents of Ministry of Education funded project(NCET-10-0664)+2 种基金the National Natural Science Foundation of China(Grant No.61134002)the National Basic Research Program of China("973"Program)(Grant No.2011CB711106)China Postdoctoral Science Foundation funded project(No:2014M550471)
文摘The theory of dynamic vibration absorber(DVA)was applied to restrain the vibration of carbody for high-speed electric multiple unit(EMU).The carbody was modeled as an Euler-Bernoulli beam with the equipment mounted on the chassis regarded as a DVA.Suspension parameters of the equipment were optimized based on the modal analysis of the beam and parameter optimization of the DVA.Vertical motion equations of the carbody and equipment were derived to study the effect of the suspension parameters on the vibration of carbody,which included the suspension frequency,damping ratio,mounting position and mass.Then a 3D rigid-flexible coupled vehicle system dynamics model was built to simulate the response of carbody and equipment to track excitation.The results show that the equipment mounted on the carbody chassis can be regarded as a DVA to reduce the flexible vibration of carbody,and the optimum suspension frequency can be calculated theoretically with the first-order vertical bending mode of carbody considered.Heavy equipment should be mounted to the carbody center as close as possible to obtain a significant vibration reduction,while light equipment has quite limited contribution to that.Also,a laboratory test was conducted on the full-scale test rig which shows a good agreement with the theoretical analysis and dynamic simulations.The faster the vehicle runs,the more significant are the advantages of the elastic suspension.
