Multiple Electrodynamic Shakers

Ebook 16 points out that conventional shakers are single-axis, whereas the “real world” is multiaxis. For many years, test personnel have attached their loads to the conventional ED shaker armature with first the load’s X-axis being aligned with the shaker’s motion axis. Then Y. Then Z. Three tests, probably three fixtures.


We see the pioneer US Army multiaxis installation at White Sands Proving Ground.  Here three ED shakers connect to the multiaxis moving platform via spherical hydrostatic bearings that thrust yet protect the individual shakers.  We also see three-shaker “stacks” at the US Army’s Research Lab and at the US Navy facility at Keyport, Washington.  We also see a US Air Force installation in Utah, that is operated by Boeing for commercial multiaxis vibration testing. The eight shakers (four vertical, two N-S and two E-W, each rated at 20,000 pounds force drive a common load, a 40 inch square magnesium weldment, to which test articles are attached.


Such arrangements are difficult and expensive. Now we visit Spectrum Technologies, a commercial test lab at Redford, Michigan, which imported from Japan and uses the IMV 3-ED-shaker system shown. Several Japanese and Chinese firms offer such systems.  Team offers two sizes of 12-ED shaker 6DoF platform shown.


16.1  Multiple shakers, single axis


16.2  Using existing ED shakers for multiaxis testing


16.3  Two-axis ED shaker Systems


16.4  Multishaker, multiaxis systems


16.5  Earthquake simulation


16.6  Tilted fixtures are not multi-axis