Gage Grid Failure (Open Circuit)

Assuming that the strain gage readings were within the strain range capability of the gage, and that the backing remains bonded, premature grid failures are often the result of high local strains within the area covered by the gage. Since the strain gage is an averaging device, it will indicate average strain along its grid length. Steep strain gradients can cause localized excessive strain damage while the gage may have been indicating a strain that was well within its elongation limits.

Grid failures may also result from strain concentrations caused by inclusions in the adhesive layer (unmixed adhesive particles, dirt, etc.) or by uneven gluelines, often caused by irregular or pitted specimen surfaces or uneven clamping pressures.

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