This paper presents two numerical realization of Preisach model by Density Function Method (DFM) and F Function Method (FFM) for a giant magnetostrictive actuator (GMA). Experiment and simulation showed that FFM is be...This paper presents two numerical realization of Preisach model by Density Function Method (DFM) and F Function Method (FFM) for a giant magnetostrictive actuator (GMA). Experiment and simulation showed that FFM is better than DFM for predicting precision of hysteresis loops. Lagrange bilinear interpolation algorithm is used in Preisach numerical realization to enhance prediction performance. A set of hysteresis loops and higher order reversal curves are predicted and experimentally verified. The good agreement between the measured and predicted curves shows that the classical Preisach model is effective for modelling the quasi-static hysteresis of the GMA.展开更多
Using an infrared thermographic technique, the temperature field during laser welding of TA15 is quantitatively measured and investigated. The ilffluenee of two welding parameters on the weld temperature distribution ...Using an infrared thermographic technique, the temperature field during laser welding of TA15 is quantitatively measured and investigated. The ilffluenee of two welding parameters on the weld temperature distribution is analyzed and the meehanisnl is discussed. New conclusions are drawn that are different from conventional weld temperature distributions. For the face of the weld, changes in welding speed induce changes in the temperature distribution because of different heat inputs and the cooling effect. Sinfilar temperature features in the welds are observed for all speeds, which exhibit a relatively low temperature area below 1 500 ℃ between the high temperature area in the position of laser incidence and the sub-high temperature area at the end of the molten pool. For the ilffluenee of laser power on the face of the weld, the temperature on the weld is higher for P = 2.8 kW compared to P = 2.0 kW, especially the temperature in the sub-high temperature area. However, for the temperature field of the back of the weld, the ilffluenee of welding speeds is quite different compared to the results for the face of the weld. The highest temperature does not locate in the keyhole area, but instead in the middle of the molten pool. And there are different temperature features at different speeds. When v = 6 m/min, the temperature field is like a uniform color belt and the temperature along the center of the weld fluctuates between 300 and 450 ℃. When v = 4 m/rain, the transient temperature distribution is not uniform and is unstable at different times. However, for v = 2.4 m/rain and lower speeds, the temperature field becomes stable. The ilffluenee of laser power on the back of the weld temperature field is more complex. The measured temperature does not increase with increasing laser power, which seems to eolffliet with the conventional thermal conduction theory-. This may be related with the characteristics of the keyhole area.展开更多
Whether the Terfenol-D rod should be laminated is of concern at the beginning of designing a magnetostrictive actuator for dynamic applications. Lamination can reduce the eddy current loss, but also decrease the stiff...Whether the Terfenol-D rod should be laminated is of concern at the beginning of designing a magnetostrictive actuator for dynamic applications. Lamination can reduce the eddy current loss, but also decrease the stiffness of the GMM rod. The conventional way by is complicated FEM （Finite-Element Method） or one＇s experience. In this article an analytical approach of magnetic field distribution in the cross-section of the rod was described, and it was introduced as a reference method to judge if the Terfenol-D rod should be laminated. Numerical evaluation and experimental results proved the rationality and availability of the approach.展开更多
Giant magnetostrictive actuators (GMAs) often work in a close-loop feedback system. This system needs independent sensors which may be difficult to be fixed, besides, excessive sensors may cause more unpredicted probl...Giant magnetostrictive actuators (GMAs) often work in a close-loop feedback system. This system needs independent sensors which may be difficult to be fixed, besides, excessive sensors may cause more unpredicted problems in a large system. This paper aims to develop a self-sensing GMA. An observer based on piezomagnetic equations is constructed to estimate the stress and strain of the magnetostrictive material. The observer based self-sensing approach depends on the facts that the magnetic field is controllable and that the magnetic induction is measurable. Aiming at the nonlinear hysteresis in magnetization, a hys- teresis compensation observer based on Preisach model is developed. Experiment verified the availability of the observer approach, and the hysteresis compensation observer has higher tracking precision than linear observer for dynamic force sensing.展开更多
The kinematic accuracy is a key factor in the design of parallel or hybrid machine tools. This analysis improved the accuracy of a 4-DOF (degree of freedom) gantry hybrid machine tool based on a 3-DOF planar parallel...The kinematic accuracy is a key factor in the design of parallel or hybrid machine tools. This analysis improved the accuracy of a 4-DOF (degree of freedom) gantry hybrid machine tool based on a 3-DOF planar parallel manipulator by compensating for various positioning errors. The machine tool architecture was described with the inverse kinematic solution. The control parameter error model was used to analyze the accuracy of the 3-DOF planar parallel manipulator and to develop a kinematic calibration method. The experimental results prove that the calibration method reduces the cutter nose errors from ±0.50 mm to ±0.03 mm for a horizontal movement of 600 mm by compensating for errors in the slider home position, the guide way distance and the extensible strut home position. The calibration method will be useful for similar types of parallel kinematic machines.展开更多
A new method of absolute phase evaluation for three-dimensional （3D） profilc measurement using fringe projection is presented, which combines the gray code and the phase shift technique. Two kinds of fringe patterns...A new method of absolute phase evaluation for three-dimensional （3D） profilc measurement using fringe projection is presented, which combines the gray code and the phase shift technique. Two kinds of fringe patterns are projected onto the object surface respectively, one is sinusoidal intensity distribution used for phase demodulation and the other is gray code fringe pattern for unwrapping. These images are acquired by camera and stored into computer. The absolute phase is obtained by analyzing these images. The validity of this method is verified experimentally. The method is superior to other phase unwrapping methods.展开更多
This study presents a new method to solve the difficult problem of precise machining a non-cylinder pinhole of a piston using embedded giant magnetostrictive material (GMM) in the component. We propose the finite elem...This study presents a new method to solve the difficult problem of precise machining a non-cylinder pinhole of a piston using embedded giant magnetostrictive material (GMM) in the component. We propose the finite element model of GMM smart component in electric, magnetic, and mechanical fields by step computation to optimize the design of GMM smart com-ponent. The proposed model is implemented by using COMSOL multi-physics V3.2a. The effects of the smart component on the deformation and the system resonance frequencies are studied. The results calculated by the model are in excellent agreement (relative errors are below 10%) with the experimental values.展开更多
To obtain the influence of fluid pressure and temperature on warm hydroforming of 5A06-O aluminum alloy sheet, the unified mechanics equilibrium equations, which take through- thickness normal stress and friction into...To obtain the influence of fluid pressure and temperature on warm hydroforming of 5A06-O aluminum alloy sheet, the unified mechanics equilibrium equations, which take through- thickness normal stress and friction into account, were established in spherical coordinate system. The distribution of through-thickness normal stress in the thickness direction was determined. The relation between through-thickness normal stress and fluid pressure was also analyzed in different regions of cylindrical cup. Based on the method of subtracting one increasing function from another, the constitutive equation of 5A06-O applied to warm hydroforming was established and in a good agreement with uniaxial tensile data. Based on whether the thickness variation was taken into account, two mechanic models were established to do the comparative study. The results for the studied case show that the calculated stress values are pretty close according to the two models and consistent with results of finite element analysis; the thickness distribution in flange computed by the second model conforms to the experimental data. Finally, the influences of fluid pressure on the flange thickness and radial stress were analyzed.展开更多
Parallel manipulators for the machine tool industry have been studied extensively for various industrial applications. However, limited useful workspace areas, the poor mobility, and design difficulties of more compl...Parallel manipulators for the machine tool industry have been studied extensively for various industrial applications. However, limited useful workspace areas, the poor mobility, and design difficulties of more complex parallel manipulators have led to more interest in parallel manipulators with less than six degrees of freedom (DoFs). Several parallel mechanisms with various numbers and types of degrees of freedom are described in this paper, which can be used in parallel kinematics machines, motion simulators, and industrial robots.展开更多
基金Project supported by the National Natural Science Foundation of China (No. 50105019)China Postdoctoral Science Foundation (No. 20060390337)
文摘This paper presents two numerical realization of Preisach model by Density Function Method (DFM) and F Function Method (FFM) for a giant magnetostrictive actuator (GMA). Experiment and simulation showed that FFM is better than DFM for predicting precision of hysteresis loops. Lagrange bilinear interpolation algorithm is used in Preisach numerical realization to enhance prediction performance. A set of hysteresis loops and higher order reversal curves are predicted and experimentally verified. The good agreement between the measured and predicted curves shows that the classical Preisach model is effective for modelling the quasi-static hysteresis of the GMA.
文摘Using an infrared thermographic technique, the temperature field during laser welding of TA15 is quantitatively measured and investigated. The ilffluenee of two welding parameters on the weld temperature distribution is analyzed and the meehanisnl is discussed. New conclusions are drawn that are different from conventional weld temperature distributions. For the face of the weld, changes in welding speed induce changes in the temperature distribution because of different heat inputs and the cooling effect. Sinfilar temperature features in the welds are observed for all speeds, which exhibit a relatively low temperature area below 1 500 ℃ between the high temperature area in the position of laser incidence and the sub-high temperature area at the end of the molten pool. For the ilffluenee of laser power on the face of the weld, the temperature on the weld is higher for P = 2.8 kW compared to P = 2.0 kW, especially the temperature in the sub-high temperature area. However, for the temperature field of the back of the weld, the ilffluenee of welding speeds is quite different compared to the results for the face of the weld. The highest temperature does not locate in the keyhole area, but instead in the middle of the molten pool. And there are different temperature features at different speeds. When v = 6 m/min, the temperature field is like a uniform color belt and the temperature along the center of the weld fluctuates between 300 and 450 ℃. When v = 4 m/rain, the transient temperature distribution is not uniform and is unstable at different times. However, for v = 2.4 m/rain and lower speeds, the temperature field becomes stable. The ilffluenee of laser power on the back of the weld temperature field is more complex. The measured temperature does not increase with increasing laser power, which seems to eolffliet with the conventional thermal conduction theory-. This may be related with the characteristics of the keyhole area.
基金supported by the National Natural Science Foundation of China (60801011)
文摘Whether the Terfenol-D rod should be laminated is of concern at the beginning of designing a magnetostrictive actuator for dynamic applications. Lamination can reduce the eddy current loss, but also decrease the stiffness of the GMM rod. The conventional way by is complicated FEM （Finite-Element Method） or one＇s experience. In this article an analytical approach of magnetic field distribution in the cross-section of the rod was described, and it was introduced as a reference method to judge if the Terfenol-D rod should be laminated. Numerical evaluation and experimental results proved the rationality and availability of the approach.
基金Project supported by the National Natural Science Foundation ofChina (No. 50105019)the China Postdoctoral Science Foundation (No. 20060390337)
文摘Giant magnetostrictive actuators (GMAs) often work in a close-loop feedback system. This system needs independent sensors which may be difficult to be fixed, besides, excessive sensors may cause more unpredicted problems in a large system. This paper aims to develop a self-sensing GMA. An observer based on piezomagnetic equations is constructed to estimate the stress and strain of the magnetostrictive material. The observer based self-sensing approach depends on the facts that the magnetic field is controllable and that the magnetic induction is measurable. Aiming at the nonlinear hysteresis in magnetization, a hys- teresis compensation observer based on Preisach model is developed. Experiment verified the availability of the observer approach, and the hysteresis compensation observer has higher tracking precision than linear observer for dynamic force sensing.
基金the National High- Tech Research andDevelopm ent Program of China (No.2 0 0 2 AA4 2 1180 )and the Knowledge Innovation Program of ChineseAcademy of Sciences (No.KJCX1- X- 0 1)
文摘The kinematic accuracy is a key factor in the design of parallel or hybrid machine tools. This analysis improved the accuracy of a 4-DOF (degree of freedom) gantry hybrid machine tool based on a 3-DOF planar parallel manipulator by compensating for various positioning errors. The machine tool architecture was described with the inverse kinematic solution. The control parameter error model was used to analyze the accuracy of the 3-DOF planar parallel manipulator and to develop a kinematic calibration method. The experimental results prove that the calibration method reduces the cutter nose errors from ±0.50 mm to ±0.03 mm for a horizontal movement of 600 mm by compensating for errors in the slider home position, the guide way distance and the extensible strut home position. The calibration method will be useful for similar types of parallel kinematic machines.
基金This work was supported by the National Natural Science Foundation of China under Grant No. 50535030 and 50275120.
文摘A new method of absolute phase evaluation for three-dimensional （3D） profilc measurement using fringe projection is presented, which combines the gray code and the phase shift technique. Two kinds of fringe patterns are projected onto the object surface respectively, one is sinusoidal intensity distribution used for phase demodulation and the other is gray code fringe pattern for unwrapping. These images are acquired by camera and stored into computer. The absolute phase is obtained by analyzing these images. The validity of this method is verified experimentally. The method is superior to other phase unwrapping methods.
基金supported by the National Natural Science Foundation of China (No. 50575205)the Hi-Tech Research and Development (863) Program of China (Nos. 2006AA04Z233 and 2007AA04Z101)+1 种基金the Doctoral Foundation of Ministry of Education of China (No. 20070335204)the Zhejiang Provincial Natural Science Foundation of China (No. Z1080537)
文摘This study presents a new method to solve the difficult problem of precise machining a non-cylinder pinhole of a piston using embedded giant magnetostrictive material (GMM) in the component. We propose the finite element model of GMM smart component in electric, magnetic, and mechanical fields by step computation to optimize the design of GMM smart com-ponent. The proposed model is implemented by using COMSOL multi-physics V3.2a. The effects of the smart component on the deformation and the system resonance frequencies are studied. The results calculated by the model are in excellent agreement (relative errors are below 10%) with the experimental values.
基金co-supported by the International Cooperation of RFBR-NSFC (No. 51111120088)the financial support from the National Natural Science Foundation of China (No. 50975014)
文摘To obtain the influence of fluid pressure and temperature on warm hydroforming of 5A06-O aluminum alloy sheet, the unified mechanics equilibrium equations, which take through- thickness normal stress and friction into account, were established in spherical coordinate system. The distribution of through-thickness normal stress in the thickness direction was determined. The relation between through-thickness normal stress and fluid pressure was also analyzed in different regions of cylindrical cup. Based on the method of subtracting one increasing function from another, the constitutive equation of 5A06-O applied to warm hydroforming was established and in a good agreement with uniaxial tensile data. Based on whether the thickness variation was taken into account, two mechanic models were established to do the comparative study. The results for the studied case show that the calculated stress values are pretty close according to the two models and consistent with results of finite element analysis; the thickness distribution in flange computed by the second model conforms to the experimental data. Finally, the influences of fluid pressure on the flange thickness and radial stress were analyzed.
基金Supported by the National "973" Program of China( No.G19980 30 6 0 7
文摘Parallel manipulators for the machine tool industry have been studied extensively for various industrial applications. However, limited useful workspace areas, the poor mobility, and design difficulties of more complex parallel manipulators have led to more interest in parallel manipulators with less than six degrees of freedom (DoFs). Several parallel mechanisms with various numbers and types of degrees of freedom are described in this paper, which can be used in parallel kinematics machines, motion simulators, and industrial robots.
