Permeability of a housing material is one of the significant factors affecting the performance of Tb0.3Dy0.7Fe1.95 based magnetostrictive actuator. According to Lenz’s law the rate of flux transfer depends on permeability of housing material surrounding the terfenol-D. In this paper the co-axial coils in a free air are analysed under direct current excitation and the results are found to agree well with both analytical and Maxwell simulation. Also, the comparison of flux density distribution in co-axial coils placed inside different housing materials of magnetostrictive actuator is found by solving magnetostatic equations using Ansoft Maxwell 2D solver. The axial distribution of magnetic flux density, radial distribution of magnetic flux de...