Building a Shaker for Fatigue Testing of Electrical Components

Thanks for the help--that is a handy chart. For some reason I was thinking it had to be harder than F=ma but I guess that's all there is to it. Yes I think sinusoidal will be okay (unless you have a better suggestion for finding broken wires, loose components, etc.)

I found an electric motor driven eccentric mass shaker that claims 0-4000rpm and variable force up to 1000lbs. I'm kind of leaning toward just building a clamp right onto the tube and hanging the whole thing horizontally (rope--maybe springs if we need them). I'm guessing that the force decreases with frequency for that shaker--and if it's fairly linear then we could probably get 5g on each 32lb module at about 10Hz. That's the simplest thing--do you think an eccentric motor like that will give that kind of displacement?

Ok if I went with a table--I'd probably get a frame welded with some steel angle iron and then mount the moving cradle on springs. Is the best way to go to set up a motor with a chain sprocket gearset as your speed reducer? Then the output gear would be attached to a wheel with adjustable offset stops to set the displacement. I could switch the pinion size to change the output frequency. Ok I figure for 10g at 5Hz for the full 68lb module (ignoring table mass for now) that'd be 182 ft-lb at 300rpm--about a 10hp motor. Probably double that with the cradle included. Can you just bolt something like this to the floor? Does this become a giant jackhammer?

I'm starting to think this project is going to be more involved than I anticipated.

piuscompleo,

Hanging sounds like a cheap way to get there but it won't work. You depending on gravity to to do some of the work but gravity tops out at 1g so 5-10g requires you to impart forces in both directions. You need a solid link and constraint system for straight line of motion. Hanging will bounce it around and get you a looping random vibration profile that you will not be sure what your getting. It could become much more vibration than you think because of line snap reactions and bouncing.

If the slide table is separately mounted. The floor doesn't need any springs under the cradle because the only force it will see is the friction in the slide bearings. The motor WILL be a giant jack hammer. BUT if you setup the shaker to be secured to the floor for lateral forces you will be using concrete in its strongest direction. If the motor is on springs you will have to be sure it can only bounce up and down. If you setup the forces to slide the test specimen laterally, you can't allow it to split the reaction forces from your required displacement and put part of it into moving the motor side to side instead of the part you are testing. If your motor bounces side to side at all it will rob displacement and force from your test specimen.