Crack Paths 2009

In parallel with the experiments, the finite element method, ABAQUS/CAEw,as used to

find the stress intensity factors and T-stress. In order to check the accuracy of the numerical

analysis, a uniaxial tensile model was generated for a centre-cracked large plate with

a/w=0.08 and w/h=1, in which a is the crack length, w is width of specimen and h is height

of specimen. The T-stress was determined for a range of loads and compared to an analysis

published by Fett [12]. The results showed only 0.6% difference when compared to the

published data. A double-edge-cracked rectangular plate (a/w=0.4 and h/w>1.5) was also

modelled using FE. In this case T-stress results were about 2 % different from those in

reference [12]. Therefore it was considered that the FE method could be used as a

comparison for the experiments.

In numerical simulation of the problem, an elastic model as shown in Figure 4 was used

in A B A Q U S Q.uarter point singular elements used to model the elastic singularity ahead of

the crack tip and the stress intensity factors were determined using the J integral method.

The T-stress was also determined using an interaction integral technique.

Figure 4: FE model created in A B A Q U S

Experimentally determined mode I stress intensity factors are in good agreement with

the numerically simulated cases, see Figure 5(a). The average differences were 12.6% (with

standard deviation of 8.8%) using 3 terms solution and 12.9% (with standard deviation of

11.5%) using converged term solution.

Almost the same trend as the mode I stress intensity factors is observed (Figure 5 (b))

for the experimentally determined T-stress when compared to the FE results. The average

differences of 24.9% (with standard deviation of 2.2%) and 35.4% (with standard deviation

of 14.9%) were found using 3 terms and converged term solutions, respectively. The

agreement between the numerical and experimental results obtained for the T-stress is not

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