Wire wound strain gauge

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Wirewound strain gauge

There are two types of wirewound strain gauge  bonded and unbonded.

Bonded strain gauge



It consists of specimen surface  Gauge is directly bonded with the surface of the specimen  surface being tested.


The thin layer of adhesive cement is also there this cement is  not only serve to transmit the strain from the specimen to the gauge wire but also act as an insulator.

Depending upon the application the bonded strain gauge have various structure so we can use this structure as our application.


Unbonded strain gauge

These strain gauges are not directly bonded onto the surface of the structure under study. Hence they are termed as unbounded strain gauges.

Description of the Unbonded Strain gauges:

The arrangement of an unbonded strain gauges consists of the following. Two frames P and Q carrying rigidly fixed insulated pins as shown in diagram. these two frames can move relative with respect to each other and they are held together by a spring loaded mechanism. A fine wire resistance strain gauge is stretched around the insulated pins. The strain gauge is connected to a wheat stone bridge.


Operation of Unbonded strain gauges:

When a force is applied on the structure under study (frames P & Q), frames P moves relative to frame Q, and due to this strain gauge will change in length and cross section. That is, the strain gauge is strained.

This strain changes the resistance of the strain gauge and this change in resistance of the strain gauge is measured using a wheat stone bridge. This change in resistance when calibrated becomes a measure of the applied force and change in dimensions of the structure under study.







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