Abstract：In view of the inconsistent dimension problem in current load separation theory, a nodimensional load separation method according to similarity principle was proposed. The universality of the nondimensional load separation properties corresponding to CT and SEB specimens has been successfully certificated by elastic plastic finite element analyses. On the basis of the new nodimensional load separation principle, improvement on the separation parameter Spb method has been conducted. The effect of the selection of reference blunt cracked specimen and calibration points on the instantaneous crack length determination for sharp cracked specimen has been eliminated by the modified Spb method. And the feasibility of this method is confirmed on comparison of unloading compliance method. By use of the modified Spb method, an assessment on the crack tip opening displacement of certain welded ball valve has been carried out.
2013, Vol. 34 
