Surface and interior stress intensity factor measurement by a random speckle method

Abstract

An embedded random speckle method is developed to measure the displacement, both on the surface and interior, around a crack tip of a four-point bend specimen made of Plexiglas. From the displacement measurements in different planes across the thickness, stress intensity factors are evaluated assuming either a plane stress or a plane strain condition. The results are compared with theoretical and other experimental values. The variation of SIF across the thickness clearly demonstrates the existence of the effect of free surface.

Studies of the Effect of Microstructure on the Dynamic Behavior of Granular and Particulate Media (First Year Report)

“…Barker and Fourney (1976) showed the successful use of this technique for interior displacement measurements. Of late, speckle photography using ordinary whitelight has been developed by Chiang (1979Chiang ( , 0 1980Chiang ( , 1990 and Asundi (1982Asundi ( , 1983) which has opened a wide range of possibilities for the application of this technique.…”