A STUDY OF THE NOTCHED-BAR CREEP-RUPTURE TEST.
CALIFORNIA UNIV BERKELEY
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The uncertainty about the use of the Odqvist equations for strain predictions under biaxial tension with constant principal stress ratios and principal stress directions held fixed was resolved. Tests were run with varying stress ratios but no general conclusions were reached. Attempts to obtain a better understanding of creep-rupture by separating the initiation and propagation phases of fracture led to very encouraging results. Although the model used may turn out to be too simplified it appears to explain a number of features of creep-rupture in smooth and notched bars. Analytical studies on notched members were only partially successful. The study of the two-dimensional case of a flat strip with notches was completed, but the three-dimensional case of a rod with a circumferential notch was abandoned. Numerical solution of three-dimensional elastic-plastic or elastic-creep problems turned out generally to be more difficult than anticipated. This is unfortunate for experiments on notched strips cannot simulate the constraint present in the case of circumferentially notched rods.
- Test Facilities, Equipment and Methods