Issue 48

R. Nikhil et alii, Frattura ed Integrità Strutturale, 48 (2019) 523-529; DOI: 10.3221/IGF-ESIS.48.50 526 Figure 6(a) : AC yield plot for a /W=0.5, h /W=0.08 and M =1.6 Figure 6(b) : AC yield plot for a /W=0.7, h /W=0.32 and M =2.2 Figure 7(a) : P L vs A for h /W=0.08 and M =1.6 Figure 7(b) : P L vs A for h /W=0.32 and M =2.2 FEM ANALYSIS D FE analysis for standard C(T) geometry with base and base-weld metal configuration consisting of h/ W ratio (0.08, 0.16, 024 and 0.32), a/ W (0.45, 0.5, 0.55, 0.6, 0.65 and 0.7) and M (1.2, 1.4, 1.6, 1.8, 2 and 2.2) has been carried out using ABAQUS. Loading pins of the specimen are modeled as rigid bodies and loaded by applying displacement while all other motions of the pins are restrained. Surface-to-surface contact with a finite-sliding formulation is defined between the pins and the specimen hole. A typical C(T) geometry mesh model with constraints highlighted is shown in Fig. 2. As per ASTM E1820, high stress triaxiality at crack tip is ensured in C(T) specimens by side grooving. Hence in the present study the analysis is restricted plane strain (CPE4) condition. Elastic-perfect plastic simulations have been carried out to evaluate limit load for homogeneous C(T) specimens with a/ W ratios (0.45, 0.5, 0.55, 0.6, 0.65 and 0.7). Flow stress of 410 MPa has been input for analysis. The limit load obtained using analytical formula, Twice Elastic Slope (TES) and FE based Yield Contour (FYC) approaches are compared. FYC is obtained using AC Yield parameter in ABAQUS which provides the extent of yielding of various elements. The P L values are shown in Fig. 3. It is observed that the P L values based FYC are in good agreement with those obtained from TES and analytical solutions. Therefore, the FEM procedure adopted to evaluate the limit load could be extended to the heterogeneous C(T)specimens. Towards this, Elastic-plastic simulations have been carried out for C(T)specimens with weld width as shown in Fig. 4. The yield stress, UTS and % elongation obtained from all weld tensile test is 462 MPa, 658 MPa and 28% elongation respectively. Based on these values a bi-linear true stress-plastic strain data generated considering identical hardening behaviour for all M values as shown in Fig. 5 is used as material model input. A typical FYC corresponding to the limit load obtained for weld specimen with h/ W = 0.08, a/ W = 0.5, M = 1.6 is shown in Fig. 6(a) and for h/ W = 0.32, a/ W = 0.7, M = 2.2 is shown in Fig. 6(b). For a given load line displacement, the spread of yield contour is attributed to M and h , in case of specimen with 2