Strain Gauge | Advantages and Disadvantages , Application

What is Strain Gauge

A strain gauge is an example of passive transducer that converts a mechanical displacement into a change of resistance. It is a thin, wafer-like device which can be attached to a variety of materials by a suitable adhesive to measure the applied strain. As the structure is stressed, the resulting strain deforms the strain gauge attached with the structure. It causes an increase in the resistivity of the gauge which produces an electrical signal proportional to the deformation. The strain gauge displacement sensor consists of a structure attached with the strain gauge that elastically deforms when subjected to a displacement shown in Figure 1.32(a).

Read more : What is Strain Gauge -Types Of Strain Gauges

strain gauge with wheatstone bridge
strain gauge with wheatstone bridge

The change of resistance is very small and it is usually measured using a Wheatstone bridge circuit where a strain gauge is connected into the circuit with a combination of four active gauges for full bridge, two gauges for half bridge or a single gauge for quarter bridge. In half and quarter circuits, the bridge is completed with precision resistors.

Types of stain gauges

Based on principle of working, strain gauges are classified into

  • Mechanical
  • Electrical
  • Piezoelectric

Based on mounting, they are classified into

  1. Bonded strain gauge
  2. Unbounded strain gauge

Based on construction, they are classified into

  1. Foil strain gauge
  2. Semiconductor strain gauge
  3. Photoelectric Strain gauge

Applications of Strain Gauge : 

(i) Strain measurement
(ii) Residual stress measurement
(iii) Vibration measurement
(iv) Torque measurement
(v) Bending and deflection measurement
(vi) Compression and tension measurement

Advantages of Strain Gauge : 

(i) There is no moving part and hence no wear
(ii) Strain gauges are very precise
(iii) It is small and inexpensive
(iv) It has a high frequency bandwidth.

Disadvantages of Strain Gauge :

(i) It is non-linear
(ii) It is very sensitive to temperature.
(iii) It needs to be calibrated regularly
(iv) Strain gauges have to be applied manually. Putting them in their place consuming and costly. It is one of their biggest disadvantages

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