Force measurement

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force measurement


As we know force is a product of mass and acceleration. so, once we know the acceleration we can calculate the force by knowing the mass  of the body.

There is a so many method to measure to force given below.

  1. Strain gauge load cell
  2. Proving ring
  3. Hydraulic load cell
  4. Pneumatic load cell
  5. Reluctance load cell
  6. Inductive load cell
  7. Magneto elastic load cell
  8. Piezoelectric load cell
  9. Fibre optic load cell
  10. Resonant wire load cell

Strain gauge load cell

This is a most common type of load cell. Strain gauge load cell is Electrical type force measurement device.



As shown in the figure(b) four strain gauges are mounted on the load sensing number. Strain gauge 1 and 3 are opposite to each other and strain gauges 2 and 4 are opposite to each other.

Strain gauge 1 and 3 are at 90° as compared to strain gauge 2 and 4 as shown in the figure. strain gauges 1 and 3 measure the direct stress while strain gauges 2 and 4 measure  transverse stress.

This type of mounting of the strain gauges are called poisson arrangement.

The figure (c) show the wheatstone bridge arrangement. The four strain gauges which are mounted on the load sensing member is connected to the wheatstone bridge.

So as the force is applied on a load cell the length and diameter  of the strain gauge wire is also change according to the force applied on a load cell.

due to change in length of the strain gauge wire the resistance of the wire is also changed so the bridge becomes unbalance.

By measuring the output voltage of bridge we can calibrate the output voltage in terms of applied force on a load cell.

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