PSI - Issue 20

S.V. Suknev / Procedia Structural Integrity 20 (2019) 30–36

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S.V. Suknev / Structural Integrity Procedia 00 (2019) 000 – 000

4.2. Fracture in compression The samples manufactured from a gypsum material with a hemihydrate plaster content of 60 – 70% are tested in compression. The specific features of manufacturing of these samples and the experimental procedure are described in the work by Suknev (2008). The initiation and propagation of cracks on the boundary of the hole with a large diameter (10 mm and longer) occur gradually, which is typical for ductile fracture. Figure 3 illustrates the experimental data (points) on the value of load at the instance of the nucleation of tensile cracks on the boundary of the hole as a function of its diameter and the results of the calculation of the critical pressure using Eq. (6) on the basis of common (curve 1) and modified (curve 2) ASC. In the latter case, 2.5   . The size of 0 d is 4.5 mm in the first case and 2.0 mm in the second one. The asymptotic value of the critical pressure is equal to 0  in the first case (dashed straight line) and 0 2.7  in the second one (solid straight line). The experimental data are well described by the modified ASC.

Fig. 3. Critical pressure versus the hole diameter. The calculation is based on the ASC.

The same experimental data (points) and calculation results of the critical pressure using Eq. (8) on the basis of common (curve 1) and modified (curve 2) PSC are given in Fig. 4. In the latter case, 1   . The size of 0 d is 2.25 mm in the first case and 0.6 mm in the second one. The asymptotic value of the critical pressure in the first case is equal to 0  in the first case (dashed straight line) and 0 2.7  in the second one (solid straight line). The experimental data are also well described by the modified PSC.

Fig. 4. Critical pressure versus the hole diameter. The calculation is based on the PSC.