STRAIN GAGE CLAMPING TECHNIQUES - PRESSURE PADS (G-14)
There is a strong element of craftsmanship involved in making consistently successful strain gage installations. As for any other field, this craft has its own special tools and working materials—found by seasoned professionals to be most effective for achieving the desired results. All organic strain gage adhesives require that some form of clamping pressure be applied and maintained throughout the curing stage.
The mechanical arrangement used to obtain a steady, nonshifting clamping force obviously depends on the nature of the test object and the gage installation. Sometimes a simple spring clamp will suffice. In other cases, it may be necessary to devise a more elaborate clamping fixture.
A resilient rubber pressure pad is used to provide a uniform clamping pressure over the gage area. It should be soft enough to conform to slightly irregular surfaces but not so soft as to extrude from under the clamping plate.
Silicone gum or silicone rubber are preferred because of their high-temperature capability.
A metal clamping plate serves to distribute the clamping force over the entire area of the pressure pad. It should be formed to match the contour of the pressure pad or test part and should have sufficient thickness to prevent deformation under normal clamping force.
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