An Experimental Method for Measuring Q

Q의 실험적 측정법

  • 김동학 (전남대학교 대학원 기계공학과) ;
  • 이정현 (전남대학교 대학원 기계공학과) ;
  • 강기주 (전남대학교 기계시스템공학부)
  • Published : 2003.09.01


An experimental method to measure Q-parameter in-situ is described. The basic idea comes from the fact that the side necking near a crack tip indicates the loss of stress triaxiality, which can be scaled by Q. From the out-of-plane displacement and the in-plane strain near the surface of side necking, stress field averaged through the thickness is calculated and then Q is determined from the difference between the stress field and the HRR field corresponding to the identical J-integral. To prove the validity, three-dimensional finite element analysis has been performed for a CT configuration with side-groove. Q-value which was calculated directly from the near-tip stress field is compared with that determined by simulating the experimental procedure according to the proposed method, that is, the Q-value determined from the lateral displacement and the in-plane strain. In addition, the effect of location where the displacement and strain are measured is explored.


J-Q Theory;Side Necking;CT Speciment;Finite Element;Method


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