AN APPLICATION OF COMPUTER IMAGE-PROCESSING AND FILM REPLICA TECHNIQUE TO A NICKEL FOIL STRAIN-GAUGE

The elastic stress of a specimen subjected to repeated loads is measur ed by a microscopic observation of slip-bands in nickel foil bonded to the surface of the specimen. The relation between the stress amplitud e and the density of slip-bands in the foil is examined at various tem peratures. An image-processing system using a personal computer is app lied for an automatic measurement of the density of slip-bands in the bonded foil. The density of slip-bands replicated in a plastic film is also measured by the image-processing system, and it is in good agree ment with the density of the original slip-bands, The peak stresses in grooved shafts under bending are measured using the nickel foil gage and the image-processing system. It is found that the results are sati sfactorily accurate.