THE EFFECT OF TESTING SYSTEM CHARACTERISTICS ON FRACTURE BEHAVIOR.
Final rept. 1 Apr 64-31 Mar 65,
SYRACUSE UNIV NY
Pagination or Media Count:
In order to investigate the stiffness effects under very stiff conditions, a stiff tensile testing machine has been constructed. This machine is screw driven, has a solid-state strain gage load cell and its stiffness value is estimated at 1.0 X 10 to the 7th power lbs.in. To understnad stiffness effects due to specimen geometry changes, a photoelastic investigation of the associated changes in stress distribution and stress concentration was conducted on 8in. and 1 in. gage length CR-39 specimens, under uniform displacement boundary conditions. Analysis of isochromatics revealed considerably lower shear stresses in the shorter specimen. Examination of stress trajectories revealed that stress distribution in the vicinity of the notch was significantly different in the long and the short specimens. Stress along the length of the notch was found to be compressive in the long specimen and tensile in the short specimen. To supplement the photoelastic study of stress concentration as a function of specimen length, notch tension tests were made on center- and edge-notch specimens of different lengths under uniform displacement boundary conditions. Author