Test data were taken to quantify the repeatability of an underdamped magnetostrictive actuator. The test specimen actuator used a terfenol-d rod of 10mm diameter and 50.8 mm length to vertically accelerate a steel mass of 9.830 kilograms. The test specimen and mass were rigidly fixed to a granite block weighing approximately two tons.

One hundred (100) data samples were recorded. One was discarded, leaving the 99 shown below. The data all show:

• An initial quiescent, non-energized state followed by
  
  
• A non-ringing expansion displacement transient of a first transient period followed by
  
  
• A hold at the expanded state, showing no ringing, followed by
  
  
• A non-ringing contraction displacement transient of a second transient period followed by
  
  
• A second quiescent, non-energized state, showing no ringing, followed by
  
  
• Intentional ringing near the resonant frequency of the system followed by
  
  
• The free response ringdown envelope after the actuator was de-energized.
  

Displacement data were recorded at a rate of 100,000 samples per second. Each separate sample was aligned to a common time zero. The 99 samples were then averaged at each and every data point to produce the upper figure.




The lower figure adds the standard deviation envelope to the averaged data. The standard deviations were calculated at each and every data point.