Effect of Crack Deformation Behavior under Mixed-mode Conditions Due to Crack-surface Contact

摘要

For slant cracks making under mode I condition, it is considered that the shape of the crack surface will be different if the stress ratio is changed (from R=0 to R=-1).Using the slant fatigue cracks with slant angle of ?=45 and 60 deg. Which was defined as between crack and loading directions, the effect on mode Ⅰ and mode Ⅱstress intensity factors (KⅠ)mes, (KⅡ)mes due to the compressive residual stress and the crack surface contact was discussed.As a result, for the cracks with slant angle of ?=45 deg.,(KⅠ)mes and (KⅡ)mes calculated from the fatigue cracks of R=-1 and R=0 decreased than values from the annealed cracks individually. If to compare the fatigue cracks of R=-1 and R=0, (KⅠ)mes from R=-1 is bigger than R=0, and in reverse (KⅡ)mes from R=-1 is smaller than R=0. Second,for the cracks with slant angle of ?=60 deg., (KⅠ)mes from fatigue cracks of R=-1 and R=0 decreased than values from the annealed cracks individually. This is the same with the crack of ?=45 deg.. But (KⅡ)mes for both cracks of R=-1 and R=0 did not change practically and the values are almost the same to the annealed cracks'ones.