The structure design for high ratio of carrying capacity to deadweight is one of the challenges for the bionic mechanism,while the problem concerning high carrying capacity has not yet be solved for the existing shoul...The structure design for high ratio of carrying capacity to deadweight is one of the challenges for the bionic mechanism,while the problem concerning high carrying capacity has not yet be solved for the existing shoulder complex.A new type biomimetic shoulder complex,which adopts 3-PSS/S（P for prismatic pair,S for spherical pair） spherical parallel mechanism（SPM）,is proposed.The static equilibrium equations of each component are established by using the vector method and the equations for constrain forces with certain load are solved.Then the constrain force on the middle limb and that on the side limbs are compared in order to verify the unloading performance of the mechanism.In addition,the prototype mechanism of the shoulder complex is developed,and the force feedback experiment is conducted to verify the static analysis,which indicates that the middle limb suffers most of the external force and the effect of mechanics unloading is achieved.The 3-PSS/S spherical parallel mechanism is presented for the shoulder complex,and the realization of mechanics unloading is benefit for the improvement of the carrying capacity of the shoulder complex.展开更多
Kenya seeks to eliminate plastic packaging,an environmental scourge on a national and even continental scaleJOHN Onyango lives in Nairobi,Kenya＇s capital.As he comes out of a downtown supermarket on an afternoon in O...Kenya seeks to eliminate plastic packaging,an environmental scourge on a national and even continental scaleJOHN Onyango lives in Nairobi,Kenya＇s capital.As he comes out of a downtown supermarket on an afternoon in October,the 61-year-old mechanic is carrying fruit in a recyclable cloth bag.展开更多
In this study,a new comprehensive fully coupled elastic–hydrodynamic model is developed for a multi-layer gas foil thrust bearing(GFTB).The interaction effects among the top foil,back board,middle foil,and bottom foi...In this study,a new comprehensive fully coupled elastic–hydrodynamic model is developed for a multi-layer gas foil thrust bearing(GFTB).The interaction effects among the top foil,back board,middle foil,and bottom foil,as well as the Coulomb friction effect,are considered.The stiffness and static characteristics obtained by the experimental and theoretical approaches are in good agreement,which verifies the accuracy of the model.The contribution of each foil layer to the overall stiffness and the load-carrying mechanism are analyzed.Interaction effects of the load,preload,and rotational speed on the static performance are investigated comprehensively.Furthermore,start–stop tests are performed to achieve the lift-off speed,start-up torque,and shut-down torque under various operating conditions.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.51275443)Key Project of Ministry of Education of China(Grant No.212012)+2 种基金Hebei Provincial Natural Science Foundation of China(Grant No.E2012203034)Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20111333120004)Research Fund for Outstanding Youth in Higher Education Institutions of Hebei Province,China(Grant No.Y2011114)
文摘The structure design for high ratio of carrying capacity to deadweight is one of the challenges for the bionic mechanism,while the problem concerning high carrying capacity has not yet be solved for the existing shoulder complex.A new type biomimetic shoulder complex,which adopts 3-PSS/S（P for prismatic pair,S for spherical pair） spherical parallel mechanism（SPM）,is proposed.The static equilibrium equations of each component are established by using the vector method and the equations for constrain forces with certain load are solved.Then the constrain force on the middle limb and that on the side limbs are compared in order to verify the unloading performance of the mechanism.In addition,the prototype mechanism of the shoulder complex is developed,and the force feedback experiment is conducted to verify the static analysis,which indicates that the middle limb suffers most of the external force and the effect of mechanics unloading is achieved.The 3-PSS/S spherical parallel mechanism is presented for the shoulder complex,and the realization of mechanics unloading is benefit for the improvement of the carrying capacity of the shoulder complex.
文摘Kenya seeks to eliminate plastic packaging,an environmental scourge on a national and even continental scaleJOHN Onyango lives in Nairobi,Kenya＇s capital.As he comes out of a downtown supermarket on an afternoon in October,the 61-year-old mechanic is carrying fruit in a recyclable cloth bag.
基金supported by the National Natural Science Foundation of China(Nos.52275204,51905298,and 52075311)the Shanghai Key Laboratory of Intelligent Manufacturing and Robotics.
文摘In this study,a new comprehensive fully coupled elastic–hydrodynamic model is developed for a multi-layer gas foil thrust bearing(GFTB).The interaction effects among the top foil,back board,middle foil,and bottom foil,as well as the Coulomb friction effect,are considered.The stiffness and static characteristics obtained by the experimental and theoretical approaches are in good agreement,which verifies the accuracy of the model.The contribution of each foil layer to the overall stiffness and the load-carrying mechanism are analyzed.Interaction effects of the load,preload,and rotational speed on the static performance are investigated comprehensively.Furthermore,start–stop tests are performed to achieve the lift-off speed,start-up torque,and shut-down torque under various operating conditions.
