3.1 FE Debond Analysis
The creep-fatigue crack growth tests explained in Chapter 2 were simulated using the ABAQUS debond analysis option [43]. Figure 3 shows the FE mesh of the C(T) specimen, consisting of 1 4,964 two-dimensional (2-D) plane strain second-order solid elements with reduced integrations (CPE8R). For loading and unloading, the static structural analysis option, *STATIC, was used and for creep-hold, the quasi-static analysis option, *VISCO, was used with the user-subroutine CREEP. The FE analysis was performed using the large geometry change option (NLGEOM in ABAQUS). To simulate crack growth, the debond option in ABAQUS was used using the *FRACTURE CRITERION, TYPE=CRACK LENGTH keyword option. The debond analysis method is schematically described in Fig. 4, where the experimentally-measured crack extension data were given as a function of time using the crack length criteria. The crack advances according to the crack length input by releasing nodes. Outputs were the load-line displacement, crack tip stress and strain fields.