Electrodynamic Shakers

<p>Are you involved with the reliability testing of aerospace and other electronics? Then you need to know about electrodynamic (ED) – sometimes wrongly called electromagnetic – shakers. In general, their frequency range is 5 or 10 to 2,000 Hz. </p>

<p>Among their advantages is the fact that (assuming little or no power amplifier distortion) ED shakers deliver the purest sinusoidal vibration and (for reproducing complex and/or random waveforms) do so with the greatest fidelity. </p>

<p>A disadvantage is cost (including the power amplifier) per pound of force. Another is short stroke, for many years 1 inch (25 mm). As of 2011, most are 2 inches (50 mm) and a few 3 inches (75 mm). Some older shakers are being reworked for greater stroke. Section 16.5 shows ED shakers used for seismic testing, with 500 mm stroke.</p>

15.1. ED shakers – theory, history and uses

  15.2. Construction details

  15.3. Degaussing or demagnetizing coil

  15.4. Wanted and unwanted armature motions

  15.5. Guidance

  15.6. Spare armature

  15.7. Isolating the shaker

  15.8. Long-stroke shakers

  15.9. Single-turn driver coil

  15.10. Cooling of shaker

  15.11. Quieting the cooling blower

  15.12. Electrodynamic shaker system

  15.13. Stroke, force and velocity limits

  15.14. Worker safety

  15.15. Capabilities chart

  15.16. Narrow-band random de-rating

  15.17. Remote control of shaker

  15.18. Combined environmental testing

  15.19. Torsional shakers

15.20. Piezoelectric shakers