Font Size: 

The influence of T-stress on creep crack tip stress field is studied based on finite element method in this paper. The modified boundary layer (MBL) formulation is introduced and used for the power-law creeping solids. The influences of T-stress on the creep zone and creeping fracture parameters are presented with MBL formulation and the T-stress affected creep crack tip field is also compared with the elastic field. Under the MBL formulation, the stress field for creep crack tip is investigated under different levels of T-stress. It can be found that lower negative T-stress violate the HRR singularity and elastic field greatly in creep crack tip field. The near crack tip stress field under large positive T-stress still obeys HRR singularity, while the far field is not the accurate elastic field any more. The creep zone size is also influenced by T-stress, and the small negative T-stress has the larger creep zone than that of larger T-stress at the same creep time. A novel parameter is proposed to characterize the creep zone considering the influence of T-stress on C(t) or C*-integral. For the same stress intensity factor with different T-stress levels, the constraint parameter Q under small scale creep is demonstrated to be described by a three order polynomial function of T/s₀. The research shows that the constraint parameter Q of creep crack for specimens is also verified to rely on T-stress level.

T-stress; Creep crack; Constraint effect; Creep zone size; Modified boundary layer formulation;