Vibration Systems for Modal Testing

Modal testing is a form of vibration testing of an object where the fundamental frequency modes of the object under test are determined. Modes are inherent properties of an item and are used to characterize the resonant vibration.

Vibrations are often applied to the body to be tested by way of piano wire (pulling force) or stinger (Pushing force). When the signal is transmitted through the piano wire or the stinger, the object responds by attenuating some frequencies and amplifying others. The amplified frequencies are measured as modal frequencies.

Modal and frequency response information is very important during the product development process. Resonant modes can be very damaging if not accounted for. A mode can be changed by changing the stiffness, damping or mass of the test item. The modes can also be changed by modifying the mounting.