Theoretical Modeling And Experimental Research Of Galfenol Force Sensing Based On Magnetic Field And Stress

Galfenol alloy,consisting of iron and gallium,is a class of smart materials which can be used to force sensor after piezoelectric material and Giant magnetostrictive material(GMM,Terfenol-D).Compared with piezoelectric material and Giant magnetostrictive material,Galfenol alloy have small brittleness and high tensile strength.And it can be machined,like cutting,screw and welding.What's more,magnetic propreties of it will be change when stress is applied to it.The applied stress can be knew through the measurement of the flux density.Large and alternating loads can be continuously measured by Galfenol alloy depending on above properties.A sealed force sensor is presented,in which the Galfenol alloy is taken as the sensing element.A series of researches have been done for force sensing:1?A force sensor based on Galfenol alloy is proposed,and the parametric design has been done for it.Working principle of force sensor is theoretical analyzed;Magnetic flux density of Galfenol will be change when the width and height of excitation coil varies depending on finite element method.The size of excitation coil is optimally designed;Properties of proposed seneor is compared with open flux path.Results show that magnetic flux density of force sensor is more uniform.Energy efficiency analysis shows that the energy efficiency of the proposed sensor can be increased more than 5 times that of the open structure;What's more,the distribution of flux density is learned when force sensor is exposed to alternating magnetic field.2?Global and local free energy formulations are built from different energy formulations and magnetic orientations of domain is calculated.The local free energy formulations are chosen by the comparison of above two free energy formulations.Magnetization model of Galfenol alloy is established.The experimental result and the calculated result of model are compared.Comparison shows that the magnetization model can make an accuracy prediction of magnetic properties when stress varies.3?Magneto-mechanical coupling model of force sensor are established upon the 3-D strong form.The weak form is more easily derived from strong form using Einstein's indicial notation and method of weighted residuals.Finite element method is taken to disperse the above equation and virtual work equation of integral form is built;the magneto-mechanical coupling model is derived using a series of definitions;Comparison of simulation result and experimental result show that magnetization model have a good match with the mechanical properties and magnetic properties of force sensor.4?The properties of Galfenol alloy under constant load and alternating load have been done.A testing system is developed to measure the magnetic properties of Galfenol alloy.The prototype of open flux path is machined and testing platform is constructed to study the magnetic properties of Galfenol when magnetic field varies and stress is constant;Experimental platform of force sensor is built using the testing machine.Stress dependent properties are researched when stress changes and magnetic field keeps.And above researches lay the experimental foundation for the application of Galfenol alloy on force sensors.