The strain gauge accelerometer uses the same load cell principle as the detection principle, i.e. the change in resistance of a strain gauge as its length changes. In these devices, a mass is suspended from a cantilever (attached to the instrument housing) to which strain gauges are attached as a Wheatstone bridge.
When accelerated, the mass moves, bending the cantilever and causing the strain gauges to strain. Damping is provided by a viscous fluid filled inside the housing. Using a voltmeter, it is possible to read an unbalance voltage of the Wheatstone bridge, which is proportional to the acceleration.
Strain Gauge Accelerometer Operation: The accelerometer is mounted on the structure whose acceleration is to be measured.
- Due to the vibration, the mass is vibrated and the cantilever is strained.
- As a result, the strain gages attached to the cantilever are also strained and their resistance changes.
- Therefore, a measure of this change in resistance of the strain gauge becomes a measure of the amount of strain in the cantilever.
- However, the resulting strain of the cantilever is proportional to the vibration/acceleration, so a measure of the resistance change of the strain gauges becomes a measure of the vibration/acceleration.
- The strain gauge leads are connected to a wheatstone bridge whose output is calibrated in terms of vibration/acceleration.