Recordings

Performance depends on the proper natural frequency, proper damping, hysteresis and the accuracy of the restraining springs.

Recordings

An instrument that has a weight (the movement of which is restrained by a spring) will record acceleration, velocity or displacement. Its performance depends on the proper natural frequency, proper damping, hysteresis and the accuracy of the restraining springs.

Acceleration

An accelerometer that accurately measures acceleration must have a natural frequency sufficiently greater than that of the acceleration to be measured. In addition, an accelerometer must be properly damped.

For the reasons given above, it's necessary that all instruments be engineered for their proper application. A misapplied recorder could show displacement or velocity when it was intended to record acceleration.

Velocity

A recorder that measures velocity presents a more difficult problem since the ratio of the impressed frequency to the natural frequency of the recorder must be within the ratios of that of a displacement recorder as well as an accelerometer. Therefore, the range of this recorder must be carefully selected and extensively tested in the actual condition it's to be used in order to accurately interpret these records.

Displacement

These recorders will register displacement if the natural frequency of the instrument is sufficiently less than that of the impressed frequency.

Frequency

The frequency of any recorder having a weight restrained by a spring is dependent upon one fact-the amount the weight must move per G.

The frequency formula is an inverse square function. For example, a recorder having a natural frequency of 20 hertz has a displacement of .0245 inches per G. If the recorder frequency is increased to 40 hertz, then either the weight or spring must be changed so movement under a 1 G load is reduced to 1/4 of .0245 inches, or .0061 inches. It's this inherent factor that makes it necessary to produce instruments with precision and extremely close tolerances. It can be readily seen that it would be impractical to read a chart where 1 G would be equal to .0061 inches. To make a satisfactory, moderately high frequency instrument, there must be multiplication between the movement of the weight and the recording stylus to produce a record that can be read with reasonable accuracy. Our recorders have been produced with multiplication ratios of as high as approximately 30 to 1

Recordings

Recordings

Acceleration

Velocity

Displacement

Frequency

PRODUCTS