This paper investigated the static and fatigue behaviors of steel and composite multi-leaf spring using the ANSYS V I 2 software. The dimensions of an existing conventional leaf spring of a light commercial vehicle we...This paper investigated the static and fatigue behaviors of steel and composite multi-leaf spring using the ANSYS V I 2 software. The dimensions of an existing conventional leaf spring of a light commercial vehicle were used. The same dimensions were used to design composite multi-leaf spring for the two materials, E-glass fiber/epoxy and E-glass fiber/vinyl ester, which are of great interest to the transportation industry. Main consideration was given to the effects of material composition and its fiber orientation on the static and fatigue behaviors of leaf spring. The design constraints were bending stresses, deflection and fatigue life. Compared to the steel leaf spring, the designed composite spring has much lower bending stresses and deflections and higher fatigue life cycles.展开更多
Although the shell mould casting process has a wide range of application in many fields,the prediction of casting defects is still a problem.In the present work,a typical leaf spring bracket casting of ZG310-570 was f...Although the shell mould casting process has a wide range of application in many fields,the prediction of casting defects is still a problem.In the present work,a typical leaf spring bracket casting of ZG310-570 was fabricated by shell mold casting.The finite element model and ProCAST software were utilized for simulating the filling and solidification processes of the casting;and the formation mechanism of the gas pore,and shrinkage porosity defects were analyzed.The results indicate that the gas pore and shrinkage porosity defects are formed due to air entrapment,insufficient feeding and non-sequential solidification.Subsequently,through changing the position of risers,adding a connecting channel between the risers,and setting blind risers at the U-shaped brackets,an optimized gating and feeding system was established to improve the quality of the casting.After optimization,the gas pore and shrinkage porosity defects of the leaf spring bracket casting are effectively eliminated.The experiment results with the optimized casting process are in good agreement with the numerical simulation,which verifies the validity of the finite element model in the shell mould casting.展开更多
An adaptive dynamic vibration absorber(ADVA)is designed for lowfrequency vibration suppression.The leaf springs are applied as the tuning stiffness elements.The principle of variable stiffness is analyzed to obtain th...An adaptive dynamic vibration absorber(ADVA)is designed for lowfrequency vibration suppression.The leaf springs are applied as the tuning stiffness elements.The principle of variable stiffness is analyzed to obtain the effective range of the first natural frequency variation.A classic simply supported manipulator is selected as the controlled system.The coupled dynamic model of the manipulator-ADVA system is built to obtain the maximum damping efficiency and the vibration absorption capacity of the designed ADVA.An experimental platform is set up to verify the theoretical results.It is revealed that the ADVA can adjust the first natural frequency on a large scale by changing the curvature of the leaf springs.The amplitude of the manipulator is reduced obviously with the installation of the designed ADVA.Finally,based on the short-time Fourier transformation(STFT),a stepwise optimization algorithm is proposed to achieve a quick tuning of the natural frequency of the ADVA so that it can always coincide with the frequency of the prime structure.Through the above steps,the intelligent frequency tuning of the ADVA is realized with high vibration absorption performance in a wide frequency range.展开更多
An eight-node solid-beam element based on absolute nodal coordinate formulation(ANCF)which uses cubic interpolation at the longitudinal direction and linear at the transverse direction is proposed.The element can accu...An eight-node solid-beam element based on absolute nodal coordinate formulation(ANCF)which uses cubic interpolation at the longitudinal direction and linear at the transverse direction is proposed.The element can accurately discretize the geometry represented by the Bézier volume with the same basis function order.The continuity property of the proposed beam element is verified.Advantages of the proposed element can be found in the application of leaf spring modeling.The parabolically varying thickness of the leaf can be accurately described.Components in leaf spring such as the spring eye and the rubber bushing can be assembled efficiently since the proposed element can be connected at any direction.The ANCF reference node is used to represent the rigid components and the revolute joints in the vehicle suspension system.Static I-shaped cross-section cantilever beam and flexible pendulum model are used to test the accuracy and dynamic performance of the proposed solid-beam element.The leaf spring model shows the flexibility of the element in modeling the complex mechanical system and the balance between the accuracy and the efficiency.展开更多
A group of leaf springs which provides the flexible support of stator is designed to satisfy the requirement of low vibration motor at megawatt （MW） level. Spring steel 65Mn is chosen as the material of the leaf spr...A group of leaf springs which provides the flexible support of stator is designed to satisfy the requirement of low vibration motor at megawatt （MW） level. Spring steel 65Mn is chosen as the material of the leaf spring. The size of the leaf spring is obtained by calculation and load analysis according to a deflection formula. The deflection and stiffness of the single leaf spring is calculated with both theoretical method and finite element analysis （FEA）. A deflection test platform is established based on actual force and boundary condition to verify the deflection and stiffness of the leaf spring. The results show that the maximal deflection of the three pieces of 1.2 mm leaf spring group is 0.71 mm and the stiffness of the leaf spring group is 364 N/mm, which satisfies the requirements of the motor. The design method is also applicable for other MW power level motors.展开更多
Variable Stiffness Actuator(VSA)is the core mechanism to achieve physical human–robot interaction,which is an inevitable development trend in robotic.The existing variable stiffness actuators are basically single deg...Variable Stiffness Actuator(VSA)is the core mechanism to achieve physical human–robot interaction,which is an inevitable development trend in robotic.The existing variable stiffness actuators are basically single degree-of-freedom(DOF)rotating joints,which are achieving multi-DOF motion by cascades and resulting in complex robot body structures.In this paper,an integrated 2-DOF actuator with variable stiffness is proposed,which could be used for bionic wrist joints or shoulder joints.The 2-DOF motion is coupling in one universal joint,which is different from the way of single DOF actuators cascade.Based on the 2-DOF orthogonal motion generated by the spherical wrist parallel mechanism,the stiffness could be adjusted by varying the effective length of the springs,which is uniformly distributed in the variable stiffness unit.The variable stiffness principle,the model design,and theoretical analysis of the VSA are discussed in this work.The independence of adjusting the equilibrium position and stiffness of the actuator is validated by experiments.The results show that the measured actuator characteristics are sufficiently matched the theoretical values.In the future,VSA could be used in biped robot or robotic arm,ensuring the safety of human–robot interaction.展开更多
common maize synthetic rate（ Photosynthetic characteristics were probed by sweet maize, waxy maize, high starch maize and The results revealed that leaf area index （LAI）, chlorophyll a content, chlorophyll b cont...common maize synthetic rate（ Photosynthetic characteristics were probed by sweet maize, waxy maize, high starch maize and The results revealed that leaf area index （LAI）, chlorophyll a content, chlorophyll b content,photo-PR） showed single peak curve at the whole growth stage. The stages of peak were different according to different varieties. NEAUS4 had the lowest peak and while SIDAN 19 had the highest among all stages. Ratio of chlorophyll a to b was low at seedling stage, reached the peak atjointing stage and then declined. SIDAN 19 had the lower level at the last stages.展开更多
文摘This paper investigated the static and fatigue behaviors of steel and composite multi-leaf spring using the ANSYS V I 2 software. The dimensions of an existing conventional leaf spring of a light commercial vehicle were used. The same dimensions were used to design composite multi-leaf spring for the two materials, E-glass fiber/epoxy and E-glass fiber/vinyl ester, which are of great interest to the transportation industry. Main consideration was given to the effects of material composition and its fiber orientation on the static and fatigue behaviors of leaf spring. The design constraints were bending stresses, deflection and fatigue life. Compared to the steel leaf spring, the designed composite spring has much lower bending stresses and deflections and higher fatigue life cycles.
基金financially supported by the Major Science and Technology Projects in Anhui Province (No. 18030901097)the Natural Science Foundation of Anhui Province (No.1908085QE197)the Fundamental Research Funds for the Central Universities (JZ2018HGBZ0133, JZ2019HGTA0043)
文摘Although the shell mould casting process has a wide range of application in many fields,the prediction of casting defects is still a problem.In the present work,a typical leaf spring bracket casting of ZG310-570 was fabricated by shell mold casting.The finite element model and ProCAST software were utilized for simulating the filling and solidification processes of the casting;and the formation mechanism of the gas pore,and shrinkage porosity defects were analyzed.The results indicate that the gas pore and shrinkage porosity defects are formed due to air entrapment,insufficient feeding and non-sequential solidification.Subsequently,through changing the position of risers,adding a connecting channel between the risers,and setting blind risers at the U-shaped brackets,an optimized gating and feeding system was established to improve the quality of the casting.After optimization,the gas pore and shrinkage porosity defects of the leaf spring bracket casting are effectively eliminated.The experiment results with the optimized casting process are in good agreement with the numerical simulation,which verifies the validity of the finite element model in the shell mould casting.
基金supported by the National Natural Science Foundation of China(Nos.11772010 and 11832002)the State Key Laboratory of Mechanical System and Vibration of China(No.MSV202004)。
文摘An adaptive dynamic vibration absorber(ADVA)is designed for lowfrequency vibration suppression.The leaf springs are applied as the tuning stiffness elements.The principle of variable stiffness is analyzed to obtain the effective range of the first natural frequency variation.A classic simply supported manipulator is selected as the controlled system.The coupled dynamic model of the manipulator-ADVA system is built to obtain the maximum damping efficiency and the vibration absorption capacity of the designed ADVA.An experimental platform is set up to verify the theoretical results.It is revealed that the ADVA can adjust the first natural frequency on a large scale by changing the curvature of the leaf springs.The amplitude of the manipulator is reduced obviously with the installation of the designed ADVA.Finally,based on the short-time Fourier transformation(STFT),a stepwise optimization algorithm is proposed to achieve a quick tuning of the natural frequency of the ADVA so that it can always coincide with the frequency of the prime structure.Through the above steps,the intelligent frequency tuning of the ADVA is realized with high vibration absorption performance in a wide frequency range.
基金supported by the National Natural Science Foundation of China(Grant No.11802072)Key Project of Science and Technology of Hu'nan Province(Grant No.2018GK1040).
文摘An eight-node solid-beam element based on absolute nodal coordinate formulation(ANCF)which uses cubic interpolation at the longitudinal direction and linear at the transverse direction is proposed.The element can accurately discretize the geometry represented by the Bézier volume with the same basis function order.The continuity property of the proposed beam element is verified.Advantages of the proposed element can be found in the application of leaf spring modeling.The parabolically varying thickness of the leaf can be accurately described.Components in leaf spring such as the spring eye and the rubber bushing can be assembled efficiently since the proposed element can be connected at any direction.The ANCF reference node is used to represent the rigid components and the revolute joints in the vehicle suspension system.Static I-shaped cross-section cantilever beam and flexible pendulum model are used to test the accuracy and dynamic performance of the proposed solid-beam element.The leaf spring model shows the flexibility of the element in modeling the complex mechanical system and the balance between the accuracy and the efficiency.
基金Supported by the Development and Application Research of Marine Electric Propulsion System of the Ministry of Science and Technology(2012BAG03B01)the National Natural Science Foundation of China(51205292)
文摘A group of leaf springs which provides the flexible support of stator is designed to satisfy the requirement of low vibration motor at megawatt （MW） level. Spring steel 65Mn is chosen as the material of the leaf spring. The size of the leaf spring is obtained by calculation and load analysis according to a deflection formula. The deflection and stiffness of the single leaf spring is calculated with both theoretical method and finite element analysis （FEA）. A deflection test platform is established based on actual force and boundary condition to verify the deflection and stiffness of the leaf spring. The results show that the maximal deflection of the three pieces of 1.2 mm leaf spring group is 0.71 mm and the stiffness of the leaf spring group is 364 N/mm, which satisfies the requirements of the motor. The design method is also applicable for other MW power level motors.
基金This work was supported by the National Key R&D Program of China(2018YFB1304600)National Natural Science Foundation of China(51605474,61821005)+1 种基金Key Research Program of Frontier Sciences,CAS,Grantno.ZDBS-LY-JSCollLiaoning RevitalizationTalents Program(XLYC1807090).
文摘Variable Stiffness Actuator(VSA)is the core mechanism to achieve physical human–robot interaction,which is an inevitable development trend in robotic.The existing variable stiffness actuators are basically single degree-of-freedom(DOF)rotating joints,which are achieving multi-DOF motion by cascades and resulting in complex robot body structures.In this paper,an integrated 2-DOF actuator with variable stiffness is proposed,which could be used for bionic wrist joints or shoulder joints.The 2-DOF motion is coupling in one universal joint,which is different from the way of single DOF actuators cascade.Based on the 2-DOF orthogonal motion generated by the spherical wrist parallel mechanism,the stiffness could be adjusted by varying the effective length of the springs,which is uniformly distributed in the variable stiffness unit.The variable stiffness principle,the model design,and theoretical analysis of the VSA are discussed in this work.The independence of adjusting the equilibrium position and stiffness of the actuator is validated by experiments.The results show that the measured actuator characteristics are sufficiently matched the theoretical values.In the future,VSA could be used in biped robot or robotic arm,ensuring the safety of human–robot interaction.
文摘common maize synthetic rate（ Photosynthetic characteristics were probed by sweet maize, waxy maize, high starch maize and The results revealed that leaf area index （LAI）, chlorophyll a content, chlorophyll b content,photo-PR） showed single peak curve at the whole growth stage. The stages of peak were different according to different varieties. NEAUS4 had the lowest peak and while SIDAN 19 had the highest among all stages. Ratio of chlorophyll a to b was low at seedling stage, reached the peak atjointing stage and then declined. SIDAN 19 had the lower level at the last stages.
