Effect of Constraint and Crack Contact Closure on Fatigue Crack Mechanical Behavior of Specimen under Negative Loading Ratio by Finite Element Method

Mechanical behaviors at fatigue crack tips of cracked specimens under negative loading ratios are studied in detail by the finite element method this paper. Three factors induced specimen type and on field discussed, including constraint, compressive effect (CL effect) contact closure. For mode I ratios, effects CL closure plastic strain accumulations dominant, with constraint being minor. The has monotonous zone, while both have reversed zone (RPZ) residual tensile (RTPZ). That is, higher smaller size zone; greater effect, or degree, larger RPZ RTPZ. II crack, there is only tip without closure, so accumulation much than that when they same level.