SEPARATION OF PRINCIPAL STRAINS IN PHOTOELASTIC COATINGS BY THE SLITTING METHOD

• Published in: Experimental techniques (Westport, Conn.) Conn.), 1987-05, Vol.11 (5), p.29-33
• Main Author: Redner, A. S.
• Format: Article
• Language: English
• ISSN: 0732-8818; 1747-1567
• DOI: 10.1111/j.1747-1567.1987.tb00411.x

There are several approaches for measuring individual strains using photoelastic coatings, of which a slitting method was discussed. In the slitting method a cut producing a stress-free edge was introduced along the direction of maximum strain on continuous flat- and curved-photoelastic coating on Al. The single or double grooved cut was evaluated using fringe value, wavelength, coating thickness, strain-optic material constant, and lateral sensitivity. The uniaxial strain measured with the slitting procedure agreed within 2% of that measured using electrical-resistance strain gages. This slitting method had advantages over other methods, including no additional instrumentation required, flat and curved surfaces can be evaluated, and it can be used statically or dynamically with a strobe. The main limitation discovered was the requirement of cutting the coating surface, which necessitated further measurements and skills to produce stress-free cuts. 7 ref.--A.R.(US).