Design And Research On A Cylindrical Giant Magnetostrictive Actuator

Giant Magnetostrictive Material(GMM)is a new functional material which has excellent characteristics such as high energy density,fast response speed,and large magnetostrictive coefficient.Giant Magnetostrictive Actuator(GMA)based on GMM has been wildly used in high precision machining,aerospace and military industry for its excellent performance.In order to automatically adjust the preload force of high precision ball screw in real-time,a cylindrical GMA,which is used as a preload force output device,is proposed in this paper.By calculating the output force and displacement,and considering both the performance and cost,Terfenol-D is chosen as the cylindrical GMM.Size of the cylindrical GMM is determined.Since the permeability of Terfenol-D is rather low,a magnetic circuit is developed and the magnetic field intensity is calculated.The influence of each part of the magnetic circuit is studied by simulation.Results show that length of the GMM has the biggest influence on the magnetic field intensity in it,and the relationship between them is negative,while size of other parts have little influence.Permeability of the object through the cylindrical GMA has the biggest influence on the uniformity of magnetic field in the GMM,the relationship of which is negative.Based on the simulation a magnetic circuit structure is designed and optimized considering the whole size of the cylindrical GMA.The performance of GMM depends greatly on the temperature.In order to ensure the cylindrical GMA working in its best temperature range,an oil cooling structure is designed.In this structure,the main heating source--driving coil,is soaked in the cooling oil and the cooling efficiency is studied by simulation.Results show that the oil cooling structure can provide cool and uniform temperature field.Influences of the thermal-mechanical coupling field to the output force and displacement are quantitatively studied.Results show that fine cooling can reduce the heat expanding displacement from 15μm to 2μm,and heat expanding force from 1218N to 181N.A disc spring preload structure is designed and the mechanical structure of the cylindrical GMA is checked.Results show that the maximum stress in the cylindrical GMA under 10000N load is much smaller than the permissible stress,and the maximum deformation displacement is acceptable.Performance of the cylindrical GMA is tested and results show that the output force and displacement can reach 8400N and 50μm at DC 5A,that means the cylindrical GMA design is successful.