Measurement And Study Of Strain Under Pulsed Magnetic Field

In this paper,basing on the background of popular extreme conditions and the actual situation of the laboratory,a new measurementdevice that can measurestrain of aluminum alloy tubeand magnetostriction,magnetization and pulsed magnetic field of Fe₈₃Ga₁₇ monocrystalline materialshas been designed and built.This measurement system successfully eliminates complex electromagnetic interference under pulsed magnetic field condition.Fortunately,the relationship between the stress-strain of aluminum alloy has been measuredunder pulsed magnetic field for the first time.The magnetostriction,magnetization and pulsed magnetic field of Fe₈₃Ga₁₇ have also been measured under both pulsed magnetic field and stresscondition at the same time for the first time.And through the comparison with the experimental results of steady-state field,to explore the difference experimental results of pulse magnetic field measurementThis paper has mainly three parts: the first part is to design and build the measurement system.The second part is to measure the stress-strain curve of the aluminum alloy tube under pulsed magnetic field in the process of electromagnetic forming,and explore the relationship between the forming limit and the loading rate.The third part is to achieve the simultaneous measurement of the pulsed magnetic field,magnetostriction and magnetization under the pressure condition by designing the experimental data acquisition system,and compared with the results measured by the steady-state field.Part one: electromagnetic forming technology is a kind of advanced method of metal pressure processing under the condition of pulsed strong magnetic field.In recent years,it has developed into an advanced high energy manufacturing method.On the one hand,the measurements of strain under this technical conditionsfocus on cutting-edge basic research,on the other hand,focus on the practical application of the quality control under the conditions of the process.The new phenomenon and new effect may occur underextreme experimental conditions,whichattractus deeply.Although there are many kinds of measurement methods,we finally chose the cheap,simple,convenient,faster frequency response strain gauge method when consider the existing experimental conditions.However,manyinvestigationshave reported that this method had a fatal drawback which is unable to get rid ofcomplicated electromagnetic interference.Facing the opportunities and the challenges at the same time,we are not afraid of difficulties,and ultimately design and build a set of measurement system which can resist to complex electromagnetic interference in the simple laboratory.The designed instrument consist threemain parts: electromagnetic force generating system;strain gauge sensor and an AC resistance bridge;experimental data acquisition system: mainly have a lock-in amplifier,preamplifier,Oscilloscope and other components.Finally,in order to verify the reliability of the experimental measurement system,we compared the equipment with a precision grating optical fiber to measure the strain under the same conditions.The experimental results show that the strain curves of the aluminum alloy tube are basically the same in the two test systems.Part two:we have measured the stress-strain curve and strain of the aluminum alloy tube in the process of electromagnetic forming used by self-build experimental system.Later on,we explore the relationship between the forming limit and the loading rate.The experimental results show that the stress-strain curve relationship of the aluminum alloy tube under fast pulsed magnetic field is successfully measured for the first time and that the increase of the loading rate can increase the forming limit.Part three: the magnetostrictive materials have a wide range of applications,recent years,FeGa systemmagnetostrictive materials has been favored by a large number of researchers with high magnetostriction,low saturation field,easy processing and so on.However,there are few researchesabout pulsed magnetic field conditions.Therefore,we have great interest in studying the magnetostriction and magnetization of Fe₈₃Ga₁₇ single crystal under pulsed magnetic field.The experimental results show that the simultaneous measurement of the pulsed magnetic field,the magnetization and the magnetostriction are carried out under the pressure condition,and the comparison between the measured results in the pulsed field and the steady state are discussed,which playsan important role in understanding the performance of materials under different conditions.