1, How do you attach the hardware you’re testing to your shaker?
By means of a fixture, usually aluminum or magnesium for lightness
coupled with rigidity. They can be cast, or smaller fixtures
machined from solid stock. Most fixtures are welded.
2, How do you control shakers?
If we’re looking for resonances in the product we’re testing, we
command the shaker to shake the product at one frequency at a time
but to vary that test frequency, to sweep it over a range of
frequencies.But more realistically, we command the shaker to
vibrate randomly and to excite all the resonances
simultaneously.Control commands go into the keyboard of a
3, What are those resonances?Are they bad?
Have you ever noticed the steering wheel moving with rather large
displacement amplitude, larger than the input to the column? That
magnification is called resonance. Possibly it annoys you. There’s
a slight chance that in a few years that whipping of the steering
column might cause bending fatigue failure.When we shake an
automotive or ship or land vehicle instrument, we're looking for,
for example, portions of printed wiring boards (PWBs) responding
with greater motion than we're inputting. That flexing may damage
PWB wiring, it may damage the attached components, and it will
damage the soldered connections between components and the PWB.