Continent subduction is one of the hot research problems in geoscience. New models presented here have been set up and two-dimensional numerical modeling research on the possibility of continental subduction has been ...Continent subduction is one of the hot research problems in geoscience. New models presented here have been set up and two-dimensional numerical modeling research on the possibility of continental subduction has been made with the finite element software, ANSYS, based on documentary evidence and reasonable assumptions that the subduction of oceanic crust has occurred, the subduction of continental crust can take place and the process can be simplified to a discontinuous plane strain theory model. The modeling results show that it is completely possible for continental crust to be subducted to a depth of 120 km under certain circumstances and conditions. At the same time, the simulations of continental subduction under a single dynamical factor have also been made, including the pull force of the subducted oceanic lithosphere, the drag force connected with mantle convection and the push force of the mid-ocean ridge. These experiments show that the drag force connected with mantle convection is critical for continent subduction.展开更多
The large capacity servo press is traditionally realized by means of redundant actuation, however there exist the over-constraint problem and interference among actuators, which increases the control difficulty and th...The large capacity servo press is traditionally realized by means of redundant actuation, however there exist the over-constraint problem and interference among actuators, which increases the control difficulty and the product cost. A new type of press mechanism with parallel topology is presented to develop the mechanical servo press with high stamping capacity. The dynamic model considering gravity counterbalance is proposed based on the virtual work principle, and then the effect of counterbalance cylinder on the dynamic performance of the servo press is studied. It is found that the motor torque required to operate the press is a lot less than the others when the ratio of the counterbalance force to the gravity of ram is in the vicinity of 1.0. The stamping force of the real press prototype can reach up to 25 MN on the position of 13 mm away from the bottom dead center. The typical deep-drawing process with 1 200 mm stroke at 8 strokes per minute is proposed by means of five order polynomial. On this process condition, the driving torques are calculated based on the above dynamic model and the torque measuring test is also carried out on the prototype. It is shown that the curve trend of calculation torque is consistent to the measured result and that the average error is less than 15%. The parallel mechanism is introduced into the development of large capacity servo press to avoid the over-constraint and interference of traditional redundant actuation, and its dynamic characteristics with gravity counterbalance are presented.展开更多
This paper reviews recent developments of the soft abrasive flow finishing(SAF)method in constraint space.The multiphase fluid dynamics modeling,material removal mechanism,auxiliary strengthening finishing techniques,...This paper reviews recent developments of the soft abrasive flow finishing(SAF)method in constraint space.The multiphase fluid dynamics modeling,material removal mechanism,auxiliary strengthening finishing techniques,and observation of surface impact effects by abrasive particles and cavitation bubbles are presented in brief.Development prospects and challenges are given for four aspects:thin-walled curved surfaces,biomedical functions,electronic information,and precise optical components.展开更多
The object of study is about dynamic modeling and control for a 2degree-of-freedom (DOF) planar parallel mechanism (PM) with flexible links. The kinematic anddynamic equations are established according to the characte...The object of study is about dynamic modeling and control for a 2degree-of-freedom (DOF) planar parallel mechanism (PM) with flexible links. The kinematic anddynamic equations are established according to the characteristics of mixed rigid and flexiblestructure. By using the singular perturbation approach (SPA), the model of the mechanism can beseparated into slow and fast subsystems. Based on the feedback linearization theory and inputshaping technique, the large scale rigid motion controller and the flexible link vibrationcontroller can be designed separately to achieve fast and accurate positioning of the PM.展开更多
针对运营中垃圾填埋场高密度聚乙烯(high density polyethylene,HDPE)膜漏洞修补问题,提出一种将并联机构和热熔焊接加工结合起来的智能焊接机器人系统,围绕机、电、热多能域耦合系统动力学展开研究。利用键合图及旋量键合图理论分别构...针对运营中垃圾填埋场高密度聚乙烯(high density polyethylene,HDPE)膜漏洞修补问题,提出一种将并联机构和热熔焊接加工结合起来的智能焊接机器人系统,围绕机、电、热多能域耦合系统动力学展开研究。利用键合图及旋量键合图理论分别构建了电机驱动子系统、末端热熔焊执行子系统及并联机构机械本体动力学模型,得到机电热多能域系统全解动力学模型。对于给定焊缝实际执行轨迹,通过MATLAB软件状态方程求解、ADAMS软件模型动力学仿真及20-sim键合图仿真综合进行分析验证,验证了该机器人多能域系统动力学全解模型合理性,为其后续动力学参数辨识以及动力学控制研究奠定基础。展开更多
文摘Continent subduction is one of the hot research problems in geoscience. New models presented here have been set up and two-dimensional numerical modeling research on the possibility of continental subduction has been made with the finite element software, ANSYS, based on documentary evidence and reasonable assumptions that the subduction of oceanic crust has occurred, the subduction of continental crust can take place and the process can be simplified to a discontinuous plane strain theory model. The modeling results show that it is completely possible for continental crust to be subducted to a depth of 120 km under certain circumstances and conditions. At the same time, the simulations of continental subduction under a single dynamical factor have also been made, including the pull force of the subducted oceanic lithosphere, the drag force connected with mantle convection and the push force of the mid-ocean ridge. These experiments show that the drag force connected with mantle convection is critical for continent subduction.
基金supported by National Science and Technology Major Project of China(Grant Nos.2010ZX04017-013,2010ZX04004-112)National Natural Science Foundation of China(Grant No.51205248)+1 种基金Shanghai Municipal Natural Science Foundation of China(Grant No.12ZR1445200)Doctoral Programs Foundation of Ministry of Education of China(Grant No.20120073120060)
文摘The large capacity servo press is traditionally realized by means of redundant actuation, however there exist the over-constraint problem and interference among actuators, which increases the control difficulty and the product cost. A new type of press mechanism with parallel topology is presented to develop the mechanical servo press with high stamping capacity. The dynamic model considering gravity counterbalance is proposed based on the virtual work principle, and then the effect of counterbalance cylinder on the dynamic performance of the servo press is studied. It is found that the motor torque required to operate the press is a lot less than the others when the ratio of the counterbalance force to the gravity of ram is in the vicinity of 1.0. The stamping force of the real press prototype can reach up to 25 MN on the position of 13 mm away from the bottom dead center. The typical deep-drawing process with 1 200 mm stroke at 8 strokes per minute is proposed by means of five order polynomial. On this process condition, the driving torques are calculated based on the above dynamic model and the torque measuring test is also carried out on the prototype. It is shown that the curve trend of calculation torque is consistent to the measured result and that the average error is less than 15%. The parallel mechanism is introduced into the development of large capacity servo press to avoid the over-constraint and interference of traditional redundant actuation, and its dynamic characteristics with gravity counterbalance are presented.
基金supported by the National Natural Science Foundation of China(Nos.52175124 and 52305139)the Natural Science Foundation of Zhejiang Province(Nos.LZ21E050003,LY17E050004,and LQ23E050017)+1 种基金the Zhejiang Provincial Postdoctoral Merit-Based Funding Project(No.ZJ2022068)the Open Foundation of the State Key Laboratory of Fluid Power and Mechatronic Systems(No.GZKF-202125),China.
文摘This paper reviews recent developments of the soft abrasive flow finishing(SAF)method in constraint space.The multiphase fluid dynamics modeling,material removal mechanism,auxiliary strengthening finishing techniques,and observation of surface impact effects by abrasive particles and cavitation bubbles are presented in brief.Development prospects and challenges are given for four aspects:thin-walled curved surfaces,biomedical functions,electronic information,and precise optical components.
基金This project is supported by National Natural Science Foundation of China (No.50390064, No.50375099) Doctorate Foundation of Ministry of Education of China(No.20020248048).
文摘The object of study is about dynamic modeling and control for a 2degree-of-freedom (DOF) planar parallel mechanism (PM) with flexible links. The kinematic anddynamic equations are established according to the characteristics of mixed rigid and flexiblestructure. By using the singular perturbation approach (SPA), the model of the mechanism can beseparated into slow and fast subsystems. Based on the feedback linearization theory and inputshaping technique, the large scale rigid motion controller and the flexible link vibrationcontroller can be designed separately to achieve fast and accurate positioning of the PM.
文摘针对运营中垃圾填埋场高密度聚乙烯(high density polyethylene,HDPE)膜漏洞修补问题,提出一种将并联机构和热熔焊接加工结合起来的智能焊接机器人系统,围绕机、电、热多能域耦合系统动力学展开研究。利用键合图及旋量键合图理论分别构建了电机驱动子系统、末端热熔焊执行子系统及并联机构机械本体动力学模型,得到机电热多能域系统全解动力学模型。对于给定焊缝实际执行轨迹,通过MATLAB软件状态方程求解、ADAMS软件模型动力学仿真及20-sim键合图仿真综合进行分析验证,验证了该机器人多能域系统动力学全解模型合理性,为其后续动力学参数辨识以及动力学控制研究奠定基础。
