When a spring – mass – damper system is subjected to acceleration, the mass is displaced, and this displacement of the mass is proportional to the acceleration. Hence a measure of displacement of the mass becomes a measure of acceleration.
The main parts of a seismic accelerometer are as follows:
- A seismic mass is suspended from the housing of the accelerometer through a spring.
- A damper is connected between the seismic mass and the housing of the accelerometer.
- The seismic mass is connected to an electric displacement transducer.
Note: there are two types of seismic – displacement sensing accelerometers namely.
- Linear seisimic accelerometer.
- Rotational Seismic Accelerometer.
Both of the above mentioned seismic accelerometers work on the same principle and are shown in diagram.
- The accelerometer is fitted on to the structure whose acceleration is to be measured.
- Due the acceleration, the seismic mass experience a displacement and this displacement of the mass is proportional to the acceleration.
- As the mass is connected to an electric displacement transducer, the output of the transducer depends on the extent – to which the mass is displaced.
- Hence the output of the transducer is calibrated to give a direct indication of the acceleration characteristics of the structure.