Principles of Strain Gages

Principles of Strain Gages

If external tensile force or compressive force increases or decreases, the resistance proportionally increases or decreases. Suppose that original resistance R changes by ΔR because of strain ε: the following equation is set up.

Where, Ks is a gage factor, expressing the sensitivity coefficient of strain gages. General-purpose strain gages use copper-nickel or nickel-chrome alloy for the resistive elements, and the gage factor provided by these alloys is approximately 2.

Types of Strain Gages

Types of strain gages are classified into foil strain gages, wire strain gages, and semiconductor strain gages, etc.

Structure of a Strain Gage

The foil strain gage has metal foil on the electric insulator of the thin resin, and gage leads attached, as shown in Fig. 1 below.

The strain gage is bonded to the measuring object with a dedicated adhesive. Strain occurring on the measuring site is transferred to the strain sensing element via adhesive and the resin base. For accurate measurement, the strain gage and adhesive should be compatible with the measuring material and operating conditions such as temperature, etc.

Strain Gages
Transducers

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Please feel free to contact us if you have any problems with measurements or if you have questions about our products.

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Products

Here are products that support all measurement scenarios, such as strain gages, sensors, and measuring instruments.

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