Rockets are powerful stuff, and satellites and astronauts experience tremendous G-forces pushing down on them during launch. For picosatellite work, it is necessary that your design be able to withstand forces equivalent to perhaps 10 times Earth gravity-- 10Gs. To test this, the easiest way is to build a centrifuge.
Think of the spinning bucket gimmick. If you tie a bucket to a rope and fill it with water, you can make the bucket swing in a loop-the-loop over your head and not spill, as long as it is spinning fast enough. You need enough spin to counteract the 1G of the Earth's pull, so you need a spinning centrifuge of at least >1G.