The dilatometric curves of B1500HS high-strength steel at different heating rates were measured by a Gleeble-3800 thermal simulator and analyzed to investigate the effect of heating rate on *** show that the value of ...
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The dilatometric curves of B1500HS high-strength steel at different heating rates were measured by a Gleeble-3800 thermal simulator and analyzed to investigate the effect of heating rate on *** show that the value of starting temperature and ending temperature of austenite transformation increase with the rise of heating rates,whereas the temperature interval of austenite formation *** kinetic equation of austenite transformation was solved using the Johnson–Mehl–Avrami model,and the related parameters of the equation were analyzed by the Kissinger *** those calculations,the activation energy of austenite transformation is 1.01×10^6 J/mol,and the values of kinetic parameters n and ln k0 are 0.63 and 103.03,*** relationship between the volume fraction of austenite and the heating time at different heating rates could be predicted using the kinetic *** predicted and experimental results were compared to verify the accuracy of the kinetic *** microstructure etched by different corrosive solutions was analyzed,and the reliability of kinetic equation was further verified from the microscopic perspective.
This paper proposes a process-based method for generating virtual test scenarios for near-shore maritime autonomous surface ships (MASS) collision avoidance tests. The method includes a scenario complexity index to pr...
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In recent years, the mid axle train has gradually entered the transportation market because of its large loading capacity and flexible steering. The static simulation of full load bending, full load torsion and full l...
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In this paper, a bionic-based design of a series-parallel hybrid wheel-legged quadruped robot that can realize wheel-foot transformations is presented to achieve footed stable walking, and a method of measuring the st...
A multi-point flexible straightening process characterized by reciprocating bending is ***,the process is analyzed in terms of deformation mechanism and verified by numerical simulations and physical experiments of th...
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A multi-point flexible straightening process characterized by reciprocating bending is ***,the process is analyzed in terms of deformation mechanism and verified by numerical simulations and physical experiments of the straightening of a series of metal profiles with different materials and initial ***,the relationship between the bending radius and the times of reciprocating bending required to unify the curvature is discussed,and the distribution of residual stress after straightening is *** results show that the reciprocating bending process can eliminate the difference of the initial curvature,make the curvature of each section tend to be uniform;the times of reciprocating bending to reach the uniform curvature decreases with the decrease of bending *** straightness of the straightened profile obtained from the experiment and simulation is less than 0.2%,demonstrating a good feasibility of this method.
The hydraulic parallel manipulator combines the high-power density of the hydraulic system and high rigidity of the parallel mechanism with excellent load-carrying ***,the high-precision trajectory tracking control of...
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The hydraulic parallel manipulator combines the high-power density of the hydraulic system and high rigidity of the parallel mechanism with excellent load-carrying ***,the high-precision trajectory tracking control of the hydraulic parallel manipulator is challenged by the coupling dynamics of the parallel mechanism and the high nonlinearities of the hydraulic *** this study,the trajectory control of a 3-DOF symmetric spherical parallel 3UPS/S manipulator is *** on the highly coupling and nonlinear system dynamics,a compound impedance control method for a hydraulic driven parallel manipulator is proposed,which combines impedance control with the spatial motion characteristics of a parallel *** control strategy is divided into the inner and outer *** inner loop controls the impedance of the actuator in the joint space,and the outer loop controls the impedance of the entire platform in the task space to compensate the coupling of the actuators and improve the tracking accuracy of the moving *** impedance control does not require force or pressure sensors and is less dependent on modeling *** experimental results show that the compound impedance control effectively improves the tracking accuracy of the moving *** research proposes a compound impedance control strategy for a 3-DOF hydraulic parallel manipulator,which has high tracking precision with a simple and cheap system configuration.
Space deployable antenna is the key equipment in realizing the communication and data transmission between the spacecraft and the *** order to enrich the configurations of deployable antennas,the type synthesis of dep...
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Space deployable antenna is the key equipment in realizing the communication and data transmission between the spacecraft and the *** order to enrich the configurations of deployable antennas,the type synthesis of deployable mechanisms for ring truss antenna is conducted in this ***,the principle of the constraint-synthesis method based on screw theory is briefly described,the structure of the ring truss deployable antenna and its folding principle are analyzed,and the ring truss mechanism is divided into upper edges,lower edges and ***,based on the constraint-synthesis method,the type synthesis of the basic unit edges is carried out,a series of basic unit mechanisms are obtained from combining the basic unit edge mechanisms,and five mechanism units with fewer joints and simple structures are ***,simulation models of the five ring truss deployable mechanisms are built in Solidworks and Matlab software,and the deploying process is verified by the movement ***,mechanism characteristics of the five mechanisms are analyzed and discussed,and a prototype is manufactured,verifying the analysis in this *** research provides a new way for the type synthesis of spatial deployable mechanisms,and the ring truss deployable mechanisms obtained in this study can be well applied in the field of aerospace.
In recent years, Maritime Autonomous Surface Ship (MASS) has been developed rapidly and has demonstrated many new capabilities, which poses a challenge to the testing methods of autonomous ships. Currently, traditiona...
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In order to solve the problems of excess ovality and cross-section distortion of longitudinally submerged arc welding pipes after forming,a new three-roller continuous setting round process was *** process can be divi...
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In order to solve the problems of excess ovality and cross-section distortion of longitudinally submerged arc welding pipes after forming,a new three-roller continuous setting round process was *** process can be divided into three stages:loading stage,roll bending stage and unloading *** on the discretization idea,the mechanical model of the primary statically indeterminate problem of the longitudinally submerged arc welding pipes at the roll bending stage was established,and the deformation response was *** simulation and theoretical results show that there are three positive bending regions and three reverse bending regions along the circumference of the *** loading force of each roller shows growth,stability and downward trend with *** error between the theoretical fitting curve and the simulated data point is very small,and the simulation results verify the reliability of the theoretical *** experimental results show that the residual ovality decreases with the increase of the reduction,and the reduction of the turning point is the optimum *** addition,the residual ovality of the pipe is less than 0.7%without cross-section distortion,which verifies the feasibility of this process.
A Mg-6.22Gd-3.04Y-0.49Zn-0.41Zr alloy with an exclusive microstructure featuring only an intragranular lamellar long-period stacking ordered (LPSO) phase was developed via specific homogeneous and cooling techniques. ...
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