A GENERAL MODEL TO PREDICT THE ELASTIC - PLASTIC STRESS DISTRIBUTION AND FRACTURE STRENGTH OF NOTCHED BARS IN PLANE STRAIN BENDING.
STANFORD UNIV CA DEPT OF MATERIALS SCIENCE AND ENGINEERING
Pagination or Media Count:
A theoretical model for predicting elastic-plastic, plane strain stress distributions in notched bars under bend loading has been developed by combining the elastic solutions of Neuber with the slip-line field solutions of Hill. The model is used to calculate the plastic zone size as a function of the externally applied load moment, the yield stress Y, and geometrical parameters such as root radius, notch depth, and ligament depth. The theoretical predictions are found to be in very good agreement with experimentally measured values of the plastic zone size in notched bars of high nitrogen steel. The fracture strength of notched bars of the same material was measured at cryogenic temperatures and the value of K sub IC was determined. It is shown that the values are consistent with a fracture criterion based on the attainment of a critical tensile stress f over a small volume in front of the notch. Unstable fracture occurs when the plastic zones have spread to a critical distance such that the maximum tensile stress level in the plastic zone is raised from Y up to f. The model therefore related the notch strength of bars containing various notches to the materials intrinsic fracture characteristics. Author
- Structural Engineering and Building Technology