PSI - Issue 41

92 6 M.R.M. Aliha et al. / Procedia Structural Integrity 41 (2022) 87–93 Aliha et al. / Structural Integrity Procedia 00 (2022) 000 – 000 The variations of BR for the analyzed Bi-ASB specimen are shown in part (d) of Fig. 4. The value of BR is notably negative under dominant mode I loading conditions (i.e. S ′ /L>0.2), indicating that the non-singular stress component plays a considerable role in the process of dominantly pure mode I brittle fracture of the Bi-ASB specimen. However, once the loading condition is changed towards pure mode II, the negative magnitude of Biaxiality ratio decreases, indicating that T-stress has minimal influence on mode II fracture of this specimen. Fig. 4e shows the variations of θ 0 (defined schematically in Fig. 4e) for different mode mixities in the analyzed Bi-ASB specimens. This parameter rises from zero (for the pure mode I condition) to roughly 70 o (for the pure mode II condition). For mode II dominated state, this parameter varies within a small range. The plastic zone region around the crack tip of analyzed Bi-ASB specimen is also shown in Fig. 5 for a/W = 0.5, S/L = 0.7, and three distinct mode mixities (i.e. pure mode I, mixed mode I+II loading, and pure mode II). The plastic zone region is symmetric relative to the crack plane under pure mode I conditions, but its shape becomes asymmetric with regard to the crack plane under mixed-mode I/II loading conditions.

Fig. 4. Variations of mode I geometry factor (Y I ), mode II geometry factor (Y II ), non-dimensional T-stress (T * ), Biaxiality ratio (BR), and fracture initiation angle (θ 0 ) with different loading span ratios (S ′ /L) and adherent material types (a/W = 0.5, S/L = 0.7)

Fig. 5. Crack tip plastic zone of investigated Bi-ASB specimens with a/W = 0.5, S/L = 0.7, and F = 100 N for pure mode I, mixed-mode I+II, and pure mode II loading conditions.