Dash-Zero Suspension Device
Finally. A simple, reliable, affordable, easy-to-use device for producing free-free boundary conditions in dynamic testing of structures. Every modal test engineer faces the problem of how to support a test article without corrupting test results with uncertainties in support conditions. How to make it "float" as if there were no gravity? Bungee cords, coil springs, or other home-grown solutions may be marginally adequate for structures with first frequencies of 30 Hz or higher but even then, expensive test data can be corrupted by suspension stiffness, mass, modes, and worst of all, friction. Tests of low frequency modes or rigid-body (zero frequency) modes demand a much better zero-g simulation.
Derived from research for NASA and the Air Force, the Dash-Zero suspension device uses a unique frictionless air spring to produce plunge frequencies below 0.2 Hz for payloads from less than 50 lb to 350 lb per device. Its simple construction and light weight make it easy to install, operate, and maintain. Best of all, the cost is much lower than the 60350-DA active-passive device from which it is derived.
Pneumatic-Magnetic Suspension Device
Modal or other ground vibration testing of space structures often requires a suspension system that can accurately simulate the unconstrained (free-free) boundary conditions of orbit. Obtaining high fidelity in tests involving rigid-body modes or flexural modes below a few Hz imposes extreme demands on the suspension system. Moog CSA has developed a practical solution for this classic problem.