Unbonding of the Gage

Assuming the proper adhesive has been selected (see reference table ), loss of bond before maximum gage elongation is reached can usually be traced to a contaminated or improperly prepared surface. A visual examination of the bond area will usually detect this. Cured adhesive on the back of the strain gage but not on the specimen generally indicates improper or incomplete surface preparation.

It is important to note that some materials, like polyethylene, are difficult to bond; and it will not be possible to reach maximum gage elongation before bond failure.

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