PSI - Issue 28

J. Xue et al. / Procedia Structural Integrity 28 (2020) 1047–1054 J. Xue, B. Williams, S. Xu and W.R. Tyson/ Structural Integrity Procedia 00 (2019) 000–000

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Fig. 5. Comparison of CTOA predicted by the DWTT bending and tension model

The middle CTOA distribution of the bending model as a function of crack extension measured at different distances behind crack tip is shown in Fig. 6. CTOA shows little change between 0.5 mm and 3 mm, but increases slightly at 7 mm (B/2), which is about half the thickness.

Fig. 6. Comparison of CTOA as a function of crack extension at various distance behind crack tip

For the DWTT tension model, CTOA is almost the same on the surface and in the interior up to 10 mm behind the crack tip, as shown in Fig. 7. At distances larger than 10 mm (0.7B), the CTOA on the surface becomes larger than that in interior. CTOA distribution through the thickness for both DWTT bending and tension models at various crack extensions is shown in Fig. 8. At crack extensions of 30 mm and 40 mm, the CTOA is considered stable. The original thickness of the DWTT sample was 13.5 mm and half-thickness was modelled in FEA. The surface of the deformed model is about 5 mm from the mid-thickness, because of the considerable thinning across the thickness. CTOA for the DWTT tension model shows no obvious variation through the thickness, while the CTOA for the DWTT bending model shows an increase of CTOA from the mid-thickness toward the surface.