Glossary

  • A

    • Acceleration

      Acceleration is the change of velocity over a period of time, Newtons second law stated that Force was the product of mass and acceleration or put another way Acceleration = Mass/Force.

    • Accelerometer

      Is a specific type of vibration transducer which converts mechanical vibration into electrical signals using a piezoelectric crystal. There are a number of different accelerometer designs each with their own characteristics, advantages and disadvantages.

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    • Amplitude

      Is a measurement of the magnitude, intensity or size of vibration and may be measured in displacement, velocity or acceleration.

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    B

    • Band Pass Filter

      A band pass filter defines a range of vibration frequencies – the filter bandwidth - within which all frequencies are allowed to pass, thus rejecting or attenuating all frequencies above and below the band.

    • Beat Frequency

      A beat frequency will occur when two very close frequencies combine together at a particular location to form a single frequency. The amplitude will vary from a maximum to a minimum over a period of time – the beat frequency – which is related to their closeness. The closer the original frequencies are together the lower the beat frequency. It may be observed on a turboprop aircraft when the speeds of the two engines are not perfectly matched and will detected as ‘vibration/noise’ which rises and falls over a period of a few seconds.

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