PSI - Issue 13

Evgeny V. Shilko et al. / Procedia Structural Integrity 13 (2018) 1508–1513 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

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Fig. 3. The dependences of normalized Young’s modulus of the samples of fluid -saturated brittle material on dimensionless parameter R n for 3D cylindrical sample (black points) and 2D rectangular sample (red points). The normalized Young’s modulus is obtained by dividing the effective value E eff by Young’s modulus of the “dry” material E . Dashed lines are approximations by sigmoid function (6).

4. Conclusion

In the paper we showed that the magnitude of the uniaxial compressive strength of fluid-saturated brittle solids is a nonlinear monotonically decreasing function of the dynamic parameter, which characterizes the ratio of the applied strain rate to the effective rate of fluid outflow. The dependence of the strength on the mentioned dynamic parameter is approximated with a good accuracy by the sigmoid curve. The most important result of the study is shown possibility of formulating a unified dependence (function) of the compressive strength of samples of permeable brittle fluid-saturated materials on a combination of parameters that includes the ratio of the strain rate to the fluid redistribution rate and the coefficients of the pore fluid effect on the stress state and strength of the solid-phase skeleton. This sigmoid function should be formulated in terms of normalized strength and a dimensionless combination of parameters of porous material and interstitial fluid, sample dimensions and loading rate. The proposed relationships make it possible to estimate the value of the dynamic compressive strength for various brittle fluid-saturated materials and to determine the unknown values of the fluid effect constants on the basis of bringing the experimental data to a theoretical unified curve.

Acknowledgements

This research was supported by the Russian Science Foundation (Project 17-11-01232).

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