Tracking and Measuring Vibration
Page 43
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ASIMPLE form of instrument for locating and recording the intensity of vibration in a structure, is that known as a reed vibrometer. Equipment of this type is produced by the General . Electric Co.. Ltd., Magnet House, Kingsway, W,C.2.,
The instrument has a reed in the form of a steel strip, the effective length of which can be varied by turning a knob on the side of the vihrometer. The reed is adjusted until its natural frequency coincides with the frequency of the disturbing force, when it will vibrate most vigorously and can thus be easily observed. A scale on the vibrometer gives the fundamental frequency of the vibration, and by varying the position of the instrument, both vertically and horizontally, on the structure under test, not only can the natural frequency and mode of vibration be observed, but the direction in which the maximum disturbance is acting canreadily be determined.
A useful feature of the G.E.C. reed vibrometer is that it incorporates an electro-magnetic pick-up, so that it can be used in conjunction with a cathoderay tube for recording Measurement or for other purposes.