Elastic Support of Test Stands and Testing Equipment

Test stands and other testing equipment are being used worldwide to study dynamic behaviors. Tests are performed with periodic excitations, as well as with shock and random excitations. Because test stands are usually located near sensitive measuring and analyzing equipment, vibration isolation is extremely important.

A typical example of such a test stand is a shaking table, which is used for earthquake simulations that can emulate both horizontal and vertical ground motions. These tables are also used to test nuclear reactor components and models to verify the functional safety of their designs under seismic and similar loads. Other types of test stands used for testing axles, motors hydraulic systems, etc. can also be elastically supported.

The type of vibration excitation is the basic factor for the design of the elastic support system. The use of GERB elements, which isolate both structure-borne noise and vibrations, permits accurate calculations of horizontal and vertical natural frequencies of the test stand or equipment. Vertical natural frequencies as low as 1 Hz can be achieved, with the horizontal and rocking frequencies even lower.

GERB spring units are often combined with Viscodampers to quickly reduce shock excited amplitudes and to avoid major amplification of periodic excitations when operating near the resonance frequencies. GERB Viscodampers are Visco-elastic dampers, which are extremely effective in all degrees of freedom with damping forces nearly proportional to the vibration velocity.

Prestressable spring units allow for readjustments of the test stand for special test conditions or if loads are significantly altered. GERB spring units are typically secured in place with GERB adhesive pads, which eliminates the need for anchor bolts.

The most important advantages of elastic support systems for test stands and other testing equipment are:

Little or no transmission of vibration and structure-borne noise into the surroundings,

Protection of operators and other personnel from vibrations,

Optimal balance between vibration excitations and test stand capabilities,

Simple installation of both the GERB elements and the test stand,

Easy alignment and adjustment of the test stand, and

Foundation costs are reduced, e.g. elements may be installed below a mounting plate.

GERB Vibration Control Systems, Inc., 1950 Ohio Street, Lisle, IL 60532. Tel: 630-724-1660; Fax: 630-724-1664.