THE EFFECT OF TESTING SYSTEM STIFFNESS ON FRACTURE.
Rept. for 1 Apr 63-31 Mar 64,
SYRACUSE UNIV N Y
Pagination or Media Count:
A preliminary study of the influence of testing system stiffness on the fracture of center-cracked sheet specimens of 7075-T6 aluminum indicated a noticeable effect of testing system stiffness on crack propagation in that decreasing the testing system stiffness resulted in the suppression of the slow or intermittent crack growth. A controlled experimental program on titanium RS 140 to study the interplay between specimen length and crack length, the two variables affecting the stiffness of the specimen, showed an effect of testing system stiffness on both crack propagation and fracture strength. Compliance curves, obtained with a specially designed compliance gage, showed a higher strain energy release rate for a given incremental crack growth dc in short specimens. The lower fracture strength observed in short specimens may be explained on this basis. Both energy and stress considerations of the effects of testing system stiffness are presented. An analysis of stiffness effects on crack propagation behavior is attempted. Author