Magnetostrictive Torque Motor

Project Description

The team is challenged with designing an actuator that exploits the magnetostrictive properties of the material Terfenol-D. Our client, Honeywell Incorporated, wishes to incorporate this technology into the valve systems in commercial aircraft.


Terfenol-D was developed in the seventies by the U.S. Naval Ordnance Laboratory. The material is an alloy of terbium, iron, and dysprosium. Terfenol-D has the largest magnetostriction of any known material, on the order of 100 times greater than other magnetostrictive materials. This means it converts magnetic energy into mechanical energy most efficiently. Currently, Terfenol-D is primarily used for ultrasonic sonar transducers for the U.S. Navy.

What is Magnetostriction?

Magnetostriction is a characteristic of ferromagnetic materials that allows them to change their shape or dimensions during exposure to a magnetic field. Essentially, regions of magnetic polarity within the material change their orientation to line up with the external field. This process causes a change in the overall length of the material.

Project Need

Currently, there are no feasible actuators for aircraft valve systems using the magnetostrictive material Terfenol-D.


Project Goal

Develop a viable actuator that utilizes the magnetostrictive properties of Terfenol-D.


Along with the objectives and features that the design will include, our team was also given a list of criteria that the design must follow

  • At least 25lb of force exerted
  • Need at least 0.03in stroke (based off of 3in length rod)
  • Must cost less than $5000
  • Must be smaller than 3 x 5 x 12in
  • Coefficients of thermal expansion must be balanced throughout device
  • System must be cooler than 500°F
  • Greater than 1:10 ratio of input to output distances