The study of crack tip stress and strain field in elasto-plastic materials

Making use of the elastic-plastic finite element program and the small scale yielding crack tip solution, three point bend and compact tension specimens are analysed at various levels of work hardening. Special attention is given to the singular stress distribution at a crack tip, to the fracture behaviour characterized by path independent integral and by crack tip opening displacement. Comparison is made between experimental and theoretical results for a structural low alloy steel. Correlation between the two is satisfactory, the experimental data are bounded by plane strain and plane stress solutions. It is indicated that the uncertainty in the true stress-strain curve in the region of initial yield may strongly influence the theoretical calculations.The authors would like to thank Professor Dr. H.Bethge, director of the Institute of Solid State Physics and Electron Microscopy in Halle (GDR) and Professor Dr. P.Ry, director of the Institute of Physical Metallurgy, Czechoslovak Academy of Sciences in Brno for their support of this cooperative research project.