Numerical investigation of crack tip strain localization under cyclic loading in FCC single crystals

Localized strain evolution and accumulation at the notch tip of an aluminum single crystal under cyclic loading

“…Again, the results along the dominant forward band supported the previous observation on the effect of radial distance on progressive strain accumulation. Similar trends were previously shown through MBL analysis on aluminum single crystal under cyclic loading 13 …”

“…These slip‐plane traces around the kink shear band indicates that in Al single crystal, dislocation density is sufficiently high to favor the formation of this band. So these results offer conclusive evidence of the formation of kink shear band near the notch tip even on the free surface (close to plane stress condition) in a geometry with as predicted by Rice 14 and crystal plasticity finite element (CPFE) analysis by Deka and Jonnalagadda 13 and Patil et al 36 A closer inspection of these trace lines in Figure 4 also revealed that there were some narrow regions where triple slip activity was noticed as marked with circles. Earlier, for relatively higher hardening crystals like Cu and Cu‐Be, 16 regions of triple slip were observed.…”

“…As mentioned earlier, TPB sample with the a=W and L=W ratios as employed in the experiment exhibits a low positive constraint. Earlier, the plane strain MBL analysis on aluminum single crystal as discussed in Deka and Jonnalagadda 13 predicted significant progressive strain accumulation along the forward band for all the constraint levels. The current experiments also revealed that the dominant progressive strain accumulation is along the forward band.…”

“…Similar trends were previously shown through MBL analysis on aluminum single crystal under cyclic loading. 13…”

“…Hence, the results were limited to a particular constraint level in the vicinity of the crack tip. In this context, a modified boundary layer (MBL) study by Deka and Jonnalagadda, 13 incorporating the constraint effect on ratcheting, showed that the accumulation of strain is limited to certain deformation bands in aluminum single crystal under cyclic load for the crack orientation commonly used for FCC metals 14 . The focus of that study was to investigate the effect of crack tip constraint level on strain ratcheting along the shear localization bands, which was found to be dominant along the forward slip shear band.…”