The stretch bending of L-section variable-curvature SUS301L stainless-steel roof bending beams for metro vehicles was numerically simulated.The causes of defects such as wrinkling,section distortion,and poor contour a...The stretch bending of L-section variable-curvature SUS301L stainless-steel roof bending beams for metro vehicles was numerically simulated.The causes of defects such as wrinkling,section distortion,and poor contour accuracy were analysed,and the corresponding control methods were proposed.The simulation results demonstrated that wrinkling in the small-arc segment could be eliminated by setting the die clearance and adjusting the elongation reasonably.Owing to the sidewall shrinkage of the profile in the process of stretch bending,the die groove depth was correspondingly reduced.Each section of the profile was effectively supported by the bottom of the die groove,and the section distortion could be controlled.Springback was the main reason for the poor contour accuracy,which could be compensated by modifying the die surface based on the springback value.Using the above defect control methods,forming experiments were performed on a new type of stretch bending die with variable die clearance and groove depth developed in this work.Finally,high-quality components were obtained,which verified the efficacy of the defect control methods.展开更多
The inherent compliance of continuum robots holds great promise in the fields of soft manipulation and safe human–robot interaction.This compliance reduces the risk of damage to the manipulated object and its surroun...The inherent compliance of continuum robots holds great promise in the fields of soft manipulation and safe human–robot interaction.This compliance reduces the risk of damage to the manipulated object and its surroundings.However,continuum robots possess theoretically infinite degrees of freedom,and this high flexibility usually leads to complex deformations when subjected to external forces and positional constraints.Describing these complex deformations is the main challenge in modeling continuum robots.In this study,we investigated a novel variable curvature modeling method for continuum robots,considering external forces and positional constraints.The robot configuration curve is described using the developed mechanical model,and then the robot is fitted to the curve.A ten-section continuum robot prototype with a length of 1 m was developed in order to validate the model.The feasibility and accuracy of the model were verified by the ability of the robot to reach target points and track complex trajectories with a load.This work was able to serve as a new perspective for the design analysis and motion control of continuum robots.展开更多
The two coupled governing differential equations for the out-of-plane vibrations of non-uniform beams with variable curvature are derived via the Hamilton’s principle.These equations are expressed in terms of flexura...The two coupled governing differential equations for the out-of-plane vibrations of non-uniform beams with variable curvature are derived via the Hamilton’s principle.These equations are expressed in terms of flexural and torsional displacements simultaneously.In this study,the analytical method is proposed.Firstly,two physical parameters are introduced to simplify the analysis.One derives the explicit relations between the flexural and the torsional displacements which can also be used to reduce the difficulty in experimental measurements.Based on the relation,the two governing characteristic differential equations with variable coefficients can be uncoupled into a sixth-order ordinary differential equation in terms of the flexural displacement only.When the material and geometric properties of the beam are in arbitrary polynomial forms,the exact solutions with regard to the outof-plane vibrations of non-uniform beams with variable curvature can be obtained by the recurrence formula.In addition,the mode transition mechanism is revealed and the influence of several parameters on the vibration of the non-uniform beam with variable curvature is explored.展开更多
Optimizing the geometric configuration of the tool cutting surface,reducing the resistance in the cutting process and energy consumption,are always a concern.Through the method of bionic design,the directrix function ...Optimizing the geometric configuration of the tool cutting surface,reducing the resistance in the cutting process and energy consumption,are always a concern.Through the method of bionic design,the directrix function of the longitudinal section of the beaver tooth rake face is extracted,and its variable curvature characteristics are analyzed.Based on this,a turning tool with variable curvature directrix configuration rake face is designed.The cutting force experiment and machining surface quality analysis experiment were carried out with the designed tool and the linear directrix configuration rake face tool respectively.The measured data of the variable curvature directrix configuration rake face tool is better than the linear directrix configuration rake face tool and its drag reduction performance of the tool is verified by experiments.Through the analysis of the working rake angle and shear angle of the tool with variable curvature directrix configuration rake face,the relationship between the parameters of the variable curvature directrix function and the working rake angle,and shear angle has been obtained.By the method of finite element simulation analysis,the stress field in the cutting zone of two different configuration tools has been analyzed.It has been found that the tool with variable curvature directrix rake face has a‘bending moment'effect on the tool-chip interface due to its curved surface configuration,and a‘prying'effect at the tool tip.These two effects promote the separation of chips from the workpiece and make the cutting process more forcesaving.The research of this paper will have reference significance for the design and application of the curved surface configuration rake face tool.展开更多
To achieve full-surface strain measurement of variable curvature objects,a 360°3D digital image correlation(DIC)system is proposed.The measurement system consists of four double-camera systems,which capture the o...To achieve full-surface strain measurement of variable curvature objects,a 360°3D digital image correlation(DIC)system is proposed.The measurement system consists of four double-camera systems,which capture the object’s entire surface from multiple angles,enabling comprehensive full-surface measurement.To increase the stitching quality,a hierarchical coordinate matching method is proposed.Initially,a 3D rigid body calibration auxiliary block is employed to track motion trajectory,which enables preliminary matching of four 3D-DIC sub-systems.Subsequently,secondary precise matching is performed based on feature points on the test specimen’s surface.Through the hierarchical coordinate matching method,the local 3D coordinate systems of each double-camera system are unified into a global coordinate system,achieving 3D surface reconstruction of the variable curvature cylindrical shell,and error analysis is conducted on the results.Furthermore,axial compression buckling experiment is conducted to measure the displacement and strain fields on the cylindrical shell’s surface.The experimental results are compared with the finite element analysis,validating the accuracy and effectiveness of the proposed multi-camera 3D-DIC measuring system.展开更多
In this paper, a new complex variable defined as “precursive time” able to correlate general relativity (GR) and quantum field theory (QFT) in a single principle was characterized. The thesis was elaborated accordin...In this paper, a new complex variable defined as “precursive time” able to correlate general relativity (GR) and quantum field theory (QFT) in a single principle was characterized. The thesis was elaborated according to a hypothesis coherent with the “Einstein’s General Theory of Relativity”, making use of a new mathematical-topological variety called “time-space” developed on the properties of the hypersphere and explained mathematically through the quaternion of Hurwitz-Lipschitz algebra. In this publication we pay attention to the interaction between the weak nuclear force theory (EWT) and the nuclear mass of the Standard Model.展开更多
Robots are used to conduct non-destructive defect detection on wind turbine blades(WTBs)and to monitor their integrity over time.However,current inspection robots are often bulky and heavy,and struggle to detect defec...Robots are used to conduct non-destructive defect detection on wind turbine blades(WTBs)and to monitor their integrity over time.However,current inspection robots are often bulky and heavy,and struggle to detect defects in the blade's main beam,thus presenting difficulties in portability and effectiveness.To address these issues,we designed a wheel-wing composite robot equipped with a curved surface-adaptive phased array ultrasonic detection device for the detection of defects in the WTB's main beam.We determined the pose equation under different section characteristics and identified the robot's stable range of motion,thus developing a model of its kinematics.A detection device adapted for variable curvature surfaces was designed to ensure tight coupling between the robot's probe and the blade.Additionally,element differential and least-square ellipse-fitting methods were employed to analyze blades with irregular sections.The simulation results demonstrated that the prototype can stably traverse an area with a vertical angle of±14.06°at a speed of 0.25 m/s,fully covering the main beam area of the blade during walking operations.Moreover,the robot can scan the main beam area at a speed of 0.10 m/s,enabling the accurate detection of defects.展开更多
基金the National Natural Science Foundation of China(51101072)Technology Development Program of Jilin Province(20150307015GX and 20160204058GX).
文摘The stretch bending of L-section variable-curvature SUS301L stainless-steel roof bending beams for metro vehicles was numerically simulated.The causes of defects such as wrinkling,section distortion,and poor contour accuracy were analysed,and the corresponding control methods were proposed.The simulation results demonstrated that wrinkling in the small-arc segment could be eliminated by setting the die clearance and adjusting the elongation reasonably.Owing to the sidewall shrinkage of the profile in the process of stretch bending,the die groove depth was correspondingly reduced.Each section of the profile was effectively supported by the bottom of the die groove,and the section distortion could be controlled.Springback was the main reason for the poor contour accuracy,which could be compensated by modifying the die surface based on the springback value.Using the above defect control methods,forming experiments were performed on a new type of stretch bending die with variable die clearance and groove depth developed in this work.Finally,high-quality components were obtained,which verified the efficacy of the defect control methods.
基金Supported by National Natural Science Foundation of China(Grant Nos.51975566,61821005,U1908214)Key Research Program of Frontier Sciences,CAS,China(Grant No.ZDBS-LY-JSC011).
文摘The inherent compliance of continuum robots holds great promise in the fields of soft manipulation and safe human–robot interaction.This compliance reduces the risk of damage to the manipulated object and its surroundings.However,continuum robots possess theoretically infinite degrees of freedom,and this high flexibility usually leads to complex deformations when subjected to external forces and positional constraints.Describing these complex deformations is the main challenge in modeling continuum robots.In this study,we investigated a novel variable curvature modeling method for continuum robots,considering external forces and positional constraints.The robot configuration curve is described using the developed mechanical model,and then the robot is fitted to the curve.A ten-section continuum robot prototype with a length of 1 m was developed in order to validate the model.The feasibility and accuracy of the model were verified by the ability of the robot to reach target points and track complex trajectories with a load.This work was able to serve as a new perspective for the design analysis and motion control of continuum robots.
文摘The two coupled governing differential equations for the out-of-plane vibrations of non-uniform beams with variable curvature are derived via the Hamilton’s principle.These equations are expressed in terms of flexural and torsional displacements simultaneously.In this study,the analytical method is proposed.Firstly,two physical parameters are introduced to simplify the analysis.One derives the explicit relations between the flexural and the torsional displacements which can also be used to reduce the difficulty in experimental measurements.Based on the relation,the two governing characteristic differential equations with variable coefficients can be uncoupled into a sixth-order ordinary differential equation in terms of the flexural displacement only.When the material and geometric properties of the beam are in arbitrary polynomial forms,the exact solutions with regard to the outof-plane vibrations of non-uniform beams with variable curvature can be obtained by the recurrence formula.In addition,the mode transition mechanism is revealed and the influence of several parameters on the vibration of the non-uniform beam with variable curvature is explored.
基金Supported by National Natural Science Foundation of China(Grant No.51975003)。
文摘Optimizing the geometric configuration of the tool cutting surface,reducing the resistance in the cutting process and energy consumption,are always a concern.Through the method of bionic design,the directrix function of the longitudinal section of the beaver tooth rake face is extracted,and its variable curvature characteristics are analyzed.Based on this,a turning tool with variable curvature directrix configuration rake face is designed.The cutting force experiment and machining surface quality analysis experiment were carried out with the designed tool and the linear directrix configuration rake face tool respectively.The measured data of the variable curvature directrix configuration rake face tool is better than the linear directrix configuration rake face tool and its drag reduction performance of the tool is verified by experiments.Through the analysis of the working rake angle and shear angle of the tool with variable curvature directrix configuration rake face,the relationship between the parameters of the variable curvature directrix function and the working rake angle,and shear angle has been obtained.By the method of finite element simulation analysis,the stress field in the cutting zone of two different configuration tools has been analyzed.It has been found that the tool with variable curvature directrix rake face has a‘bending moment'effect on the tool-chip interface due to its curved surface configuration,and a‘prying'effect at the tool tip.These two effects promote the separation of chips from the workpiece and make the cutting process more forcesaving.The research of this paper will have reference significance for the design and application of the curved surface configuration rake face tool.
基金funded by the National Natural Science Foundations of China(Nos.12272176,U2037603).
文摘To achieve full-surface strain measurement of variable curvature objects,a 360°3D digital image correlation(DIC)system is proposed.The measurement system consists of four double-camera systems,which capture the object’s entire surface from multiple angles,enabling comprehensive full-surface measurement.To increase the stitching quality,a hierarchical coordinate matching method is proposed.Initially,a 3D rigid body calibration auxiliary block is employed to track motion trajectory,which enables preliminary matching of four 3D-DIC sub-systems.Subsequently,secondary precise matching is performed based on feature points on the test specimen’s surface.Through the hierarchical coordinate matching method,the local 3D coordinate systems of each double-camera system are unified into a global coordinate system,achieving 3D surface reconstruction of the variable curvature cylindrical shell,and error analysis is conducted on the results.Furthermore,axial compression buckling experiment is conducted to measure the displacement and strain fields on the cylindrical shell’s surface.The experimental results are compared with the finite element analysis,validating the accuracy and effectiveness of the proposed multi-camera 3D-DIC measuring system.
文摘In this paper, a new complex variable defined as “precursive time” able to correlate general relativity (GR) and quantum field theory (QFT) in a single principle was characterized. The thesis was elaborated according to a hypothesis coherent with the “Einstein’s General Theory of Relativity”, making use of a new mathematical-topological variety called “time-space” developed on the properties of the hypersphere and explained mathematically through the quaternion of Hurwitz-Lipschitz algebra. In this publication we pay attention to the interaction between the weak nuclear force theory (EWT) and the nuclear mass of the Standard Model.
基金supported by the Zhejiang Lab Open Research Project(No.121001-AB2212)the Zhejiang Provincial Key Research and Development Program(No.2023C03186),China。
文摘Robots are used to conduct non-destructive defect detection on wind turbine blades(WTBs)and to monitor their integrity over time.However,current inspection robots are often bulky and heavy,and struggle to detect defects in the blade's main beam,thus presenting difficulties in portability and effectiveness.To address these issues,we designed a wheel-wing composite robot equipped with a curved surface-adaptive phased array ultrasonic detection device for the detection of defects in the WTB's main beam.We determined the pose equation under different section characteristics and identified the robot's stable range of motion,thus developing a model of its kinematics.A detection device adapted for variable curvature surfaces was designed to ensure tight coupling between the robot's probe and the blade.Additionally,element differential and least-square ellipse-fitting methods were employed to analyze blades with irregular sections.The simulation results demonstrated that the prototype can stably traverse an area with a vertical angle of±14.06°at a speed of 0.25 m/s,fully covering the main beam area of the blade during walking operations.Moreover,the robot can scan the main beam area at a speed of 0.10 m/s,enabling the accurate detection of defects.
