The damper is capable of providing a continuously variable dampering force/torque in response to a magnetic field. It consists of an upside cap and an underside cap with a rotor located between them, the magneto-rheol...The damper is capable of providing a continuously variable dampering force/torque in response to a magnetic field. It consists of an upside cap and an underside cap with a rotor located between them, the magneto-rheological （MR） fluid is filled into the gaps between the rotor and the caps. When the viscosity of the MR fluid increases under the influence of the magnetic field, the movement of the rotor will be resisted. The output torque is made up of the torque caused by the magnetic field, the torque caused by the plastic viscosity of the MR fluid, and the torque caused by the coulomb friction. The viscous torque can be calculated by a simple method and the frictional torque can be obtained by experiments. The torque dependent on the magnetic field is obtained by electromagnetic finite dement analysis. Experiments are done on the damper prototype and the validity of the design is verified.展开更多
The effects of partial substitution of Fe element for Ni element on the structure,martensitic transformation and mechanicalproperties of Ni50-xFexMn38Sn12(x=0and3%,molar fraction)ferromagnetic shape memory alloys were...The effects of partial substitution of Fe element for Ni element on the structure,martensitic transformation and mechanicalproperties of Ni50-xFexMn38Sn12(x=0and3%,molar fraction)ferromagnetic shape memory alloys were investigated.Experimentalresults indicate that by substitution of Fe for Ni,the microstructure and crystal structure of the alloys change at room temperature.Compared with Ni50Mn38Sn12alloy,the martensitic transformation starting temperature of Ni47Fe3Mn38Sn12alloy is decreased by32.5K.It is also found that martensitic transformation occurs over a broad temperature window from288.9to352.2K.It is found that themechanical properties of Ni-Mn-Sn alloy can be significantly improved by Fe addition.The Ni47Fe3Mn38Sn12alloy achieves amaximum compressive strength of855MPa with a fracture strain of11%.Moreover,the mechanism of the mechanical propertyimprovement is clarified.Fe doping changes the fracture type from intergranular fracture of Ni50Mn38Sn12alloy to transgranularcleavage fracture of Ni47Fe3Mn38Sn12alloys.展开更多
A good mechanical model of magnetorheological damper (MRD) is essential to predict the shock isolation performance of MRD in numerical simulation. But at present, the mechanical models of MRD were all derived from the...A good mechanical model of magnetorheological damper (MRD) is essential to predict the shock isolation performance of MRD in numerical simulation. But at present, the mechanical models of MRD were all derived from the experiment subjected to harmonic vibration loads. In this paper, a commercial MRD (type RD-1005-3) manufactured by Lord Corporation was studied ex-perimentally in order to investigate its isolation performance under the impact loads. A new me-chanical model of MRD was proposed according to the data obtained by impact test. A good agreement between the numerical results and test data was observed, which showed that the model was good to simulate the dynamic properties of MRD under impact loads. It is also demon-strated that MRD can improve the acceleration and displacement response of the structure obvi-ously under impact loads.展开更多
A new type of linear rotary magnetorheological damper (MRD) is proposed, which consists of a cylinder-type MRD and a screw mechanism to transform a linear motion into revolving motion. It is found that the structure p...A new type of linear rotary magnetorheological damper (MRD) is proposed, which consists of a cylinder-type MRD and a screw mechanism to transform a linear motion into revolving motion. It is found that the structure parameters of MRD have complex relationship with the force of the damper, especially the lead angle, width and radius of the inner rotor. The analyses and simulation calculation of the static magnetic field give some usable data, and experiments of the damping component indicate that the proposed methods is feasible for developing linear rotary MRD.展开更多
Oil immersed power transformer is the main electrical equipment in power system.Its operation reliability has an important impact on the safe operation of power system.In the process of production,installation and ope...Oil immersed power transformer is the main electrical equipment in power system.Its operation reliability has an important impact on the safe operation of power system.In the process of production,installation and operation,its insulation structure may be damaged,resulting in partial discharge and even breakdown inside the transformer.In this paper,S9-M-100/10 oil immersed distribution transformer is taken as the research object,and the distribution laws of electromagnetic field and temperature field in transformer under normal operation,inter turn short circuit and inter layer short circuit are simulated and analyzed.The simulation results show that under normal conditions,the temperatures at the oil gap between the transformer core and the high and low voltage windings and the middle position of the high-voltage winding are high.When there are inter turn and inter layer short circuit faults,the electromagnetic loss of the fault part of the transformer increases,and the temperature rises suddenly.The influence of the two faults on the internal temperature field of the transformer is different,and the influence of the inter turn short circuit fault on the temperature nearby is obvious.The analysis results can provide reference for the thermal fault interpretation and fault classification of transformer.展开更多
The authors offered the new formula of the thermodynamic functions in a magnetic field. The authors have also found that thermodynamic functions of internal energy dUand free energy dF changes in the magnetic field.
This paper compares the estimated electromagnetic forces due to short circuits in power transformers using two computational models. The first model is based on approximate analytical expressions of the electromagneti...This paper compares the estimated electromagnetic forces due to short circuits in power transformers using two computational models. The first model is based on approximate analytical expressions of the electromagnetic lbrces as they have been compiled in earlier versions of the IEC standard 60076-5. The second model is based on a finite element model of the transformer using the software FEMM （Finite Element Method Magnetics）. The paper shows how valid the analytical model is for design purposes. Results have been obtained and compared from both models in a number of actual power distribution transformers. It is possible to conclude that the analytical formulation provides satisfactory results for the design of power transformers compared to detailed finite element models. A tool has been designed for this purpose and the main features of it will be described in the paper.展开更多
基金The National Basic Research Program of China(973Program) (No2002CB312102)the National Natural ScienceFoundation of China (No60675047)
文摘The damper is capable of providing a continuously variable dampering force/torque in response to a magnetic field. It consists of an upside cap and an underside cap with a rotor located between them, the magneto-rheological （MR） fluid is filled into the gaps between the rotor and the caps. When the viscosity of the MR fluid increases under the influence of the magnetic field, the movement of the rotor will be resisted. The output torque is made up of the torque caused by the magnetic field, the torque caused by the plastic viscosity of the MR fluid, and the torque caused by the coulomb friction. The viscous torque can be calculated by a simple method and the frictional torque can be obtained by experiments. The torque dependent on the magnetic field is obtained by electromagnetic finite dement analysis. Experiments are done on the damper prototype and the validity of the design is verified.
基金Projects(51471064,51301054)supported of the National Natural Science Foundation of ChinaProject(1253-NCET-009)supported by the Program for New Century Excellent Talents,China+1 种基金Project(1251G022)supported by Program for Youth Academic Backbone in Heilongjiang Provincial University,ChinaProject(12541138)supported by Scientific Research Fund of Heilongjiang Provincial Education Department,China
文摘The effects of partial substitution of Fe element for Ni element on the structure,martensitic transformation and mechanicalproperties of Ni50-xFexMn38Sn12(x=0and3%,molar fraction)ferromagnetic shape memory alloys were investigated.Experimentalresults indicate that by substitution of Fe for Ni,the microstructure and crystal structure of the alloys change at room temperature.Compared with Ni50Mn38Sn12alloy,the martensitic transformation starting temperature of Ni47Fe3Mn38Sn12alloy is decreased by32.5K.It is also found that martensitic transformation occurs over a broad temperature window from288.9to352.2K.It is found that themechanical properties of Ni-Mn-Sn alloy can be significantly improved by Fe addition.The Ni47Fe3Mn38Sn12alloy achieves amaximum compressive strength of855MPa with a fracture strain of11%.Moreover,the mechanism of the mechanical propertyimprovement is clarified.Fe doping changes the fracture type from intergranular fracture of Ni50Mn38Sn12alloy to transgranularcleavage fracture of Ni47Fe3Mn38Sn12alloys.
基金Supported by National Natural Science Foundation of China (No.50638030,50525825)the National Science and Technology SupportProgram (No.2006BAJ13B02)
文摘A good mechanical model of magnetorheological damper (MRD) is essential to predict the shock isolation performance of MRD in numerical simulation. But at present, the mechanical models of MRD were all derived from the experiment subjected to harmonic vibration loads. In this paper, a commercial MRD (type RD-1005-3) manufactured by Lord Corporation was studied ex-perimentally in order to investigate its isolation performance under the impact loads. A new me-chanical model of MRD was proposed according to the data obtained by impact test. A good agreement between the numerical results and test data was observed, which showed that the model was good to simulate the dynamic properties of MRD under impact loads. It is also demon-strated that MRD can improve the acceleration and displacement response of the structure obvi-ously under impact loads.
文摘A new type of linear rotary magnetorheological damper (MRD) is proposed, which consists of a cylinder-type MRD and a screw mechanism to transform a linear motion into revolving motion. It is found that the structure parameters of MRD have complex relationship with the force of the damper, especially the lead angle, width and radius of the inner rotor. The analyses and simulation calculation of the static magnetic field give some usable data, and experiments of the damping component indicate that the proposed methods is feasible for developing linear rotary MRD.
基金Science and Technology Project of State Grid Gansu Electric Power Company(No.52272219000Q)。
文摘Oil immersed power transformer is the main electrical equipment in power system.Its operation reliability has an important impact on the safe operation of power system.In the process of production,installation and operation,its insulation structure may be damaged,resulting in partial discharge and even breakdown inside the transformer.In this paper,S9-M-100/10 oil immersed distribution transformer is taken as the research object,and the distribution laws of electromagnetic field and temperature field in transformer under normal operation,inter turn short circuit and inter layer short circuit are simulated and analyzed.The simulation results show that under normal conditions,the temperatures at the oil gap between the transformer core and the high and low voltage windings and the middle position of the high-voltage winding are high.When there are inter turn and inter layer short circuit faults,the electromagnetic loss of the fault part of the transformer increases,and the temperature rises suddenly.The influence of the two faults on the internal temperature field of the transformer is different,and the influence of the inter turn short circuit fault on the temperature nearby is obvious.The analysis results can provide reference for the thermal fault interpretation and fault classification of transformer.
文摘The authors offered the new formula of the thermodynamic functions in a magnetic field. The authors have also found that thermodynamic functions of internal energy dUand free energy dF changes in the magnetic field.
文摘This paper compares the estimated electromagnetic forces due to short circuits in power transformers using two computational models. The first model is based on approximate analytical expressions of the electromagnetic lbrces as they have been compiled in earlier versions of the IEC standard 60076-5. The second model is based on a finite element model of the transformer using the software FEMM （Finite Element Method Magnetics）. The paper shows how valid the analytical model is for design purposes. Results have been obtained and compared from both models in a number of actual power distribution transformers. It is possible to conclude that the analytical formulation provides satisfactory results for the design of power transformers compared to detailed finite element models. A tool has been designed for this purpose and the main features of it will be described in the paper.
