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Gage Length

Gage length is the strain sensitive length of the strain gage, as illustrated on the left.

Gage length ranges from 0.2 mm to 100 mm (0.008 in - 4 in), but a length of 3 mm to 6 mm (0.125 in - 0.25 in) is generally recommended for the common applications.

  • Select a shorter gage (3mm; 0.125 in), if
  - Very little space is available for mounting the gage.
  - A localized strain gradient needs to be measured. For example,if the strain that needs to be measured is close to or on a fillet, hole, or notch with a small diameter (< 25 mm; 1 in).
  - Accuracy is not critical.
  • Select a longer gage (6mm; 0.25 in), if
  - Installation speed is important. Longer gages are easier to handle and install.
  - Heat dissipation is an issue (usually on non-metallic materials), such as in a high temperature environment or under cycling stresses. A longer gage is less sensitive to the effects of heat.
  - The object to be measured has non-homogeneous material properties, such as concrete. A gage with a length two times or more than the non-homogeneities is needed to avoid local fluctuation.
  - Cost is an issue. Gages with length of 5.0 - 12.5 mm (0.2 - 0.5 in) are usually less expensive than other lengths.