available for use In transducer construction,, Various alloys 

 proved to have properties especially useful In transducers 

 operating without benefit of an external source of magnetic 

 polarization,. 



Bell Telephone Laboratory studies indicated that no single 

 material is universally "best" for the construction of magneto- 

 striction transducers o The requirements for such an ideal 

 material are inherently contradictory,, High reversible per- 

 meability and high coercive force are both desirable, but they 

 usually increase and decrease in opposite directions, as the 

 composition and treatment of the material are varied. Fortu- 

 nately, it was found that useful compromise values could be 

 obtained. 



The third major phase of fundamental research In magneto- 

 striction transducer design concerned the analysis of the com- 

 plex vibrating system by which magnetostrictive strains are 

 converted into the vibration of a radiating surface in contact 

 with the water medium. Both the New London Laboratory and 

 HUSL conducted active programs of transducer design In which 

 various configurations of the magnetostrictive material were 

 employed in the attempt to secure desirable performance in 

 the final transducer „ 



Eddy currents constitute one of the most serious sources 

 of internal dissipation in magnetostriction transducers. In 

 units employing radial or longitudinal vibration of nickel 

 tubes, this effect is especially prominent, and led to many 

 schemes, some practical and some impractical, for reducing the 

 eddy currents by lamination. Considerable success was rea- 

 lized in minimizing the eddy currents by using stacks of flat 

 laminations 



The principal types of magnetostriction transducers made 

 available by this research program may be classified as fol- 

 lows ; 



(1) Radially vibrating tubes 



(2) Asymmetrical Laminated stacks 



(3) Laminated ring stacks 



(4) Tube and plate transducers 



(5) Miscellaneous forms 



38 - 



