PSI - Issue 20

S.V. Suknev / Procedia Structural Integrity 20 (2019) 30–36 S.V. Suknev / Structural Integrity Procedia 00 (2019) 000 – 000

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4. Experimental Verification The applicability of the quasi-brittle fracture criteria can be verified on experimental data on the fracture of plates with a hole in tension and compression. 4.1. Fracture in tension Test results for the tensile fracture of plates made of graphite/epoxy laminate with quasi-isotropic packaging of layers with circular and elliptical holes are given in the work by Tan (1987). Figure 1 illustrates experimental data (points) on the value of a fracture load as a function of the diameter of a circular hole and calculation results for the critical stress according to the ASC on the basis of Eq. (4) for 0   (curve 1) and 0.2   (curve 2). The size of 0 d is 2.1 mm in the first case and 2.0 mm in the second one. The solid straight line shows the asymptotic value of curve 2, and the dashed straight line is calculated according to the conventional approach.

Fig. 1. Critical stress versus the hole diameter. The calculation is based on the ASC.

The results of the ASC based calculations for 0.2   somewhat better describe the experimental data than for 0   , but this difference is insignificant. The FPZ size is mainly determined by 0 d , and the influence of inelastic deformations may be ignored. The same experimental data (points) and the results of the calculation of the critical stress according to the PSC with the help of Eq. (7) for 0   (curve 1) and 0.22   (curve 2) are shown in Fig. 2. The size of 0 d is 0.7 mm in the first case and 0.5 mm in the second one. The solid straight line denotes the asymptotic value of curve 2, and the dashed straight line is calculated according to the conventional approach. Note that the results of the PSC based calculation for 0.22   describe the experimental data noticeably better than for 0   .

Fig. 2. Critical stress versus the hole diameter. The calculation is based on the PSC.