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A Study on Subcritical Crack Growth Parameters in Rock-like Material under Monotonic and Cyclic Loading

단조 및 반복하중 하에서의 모사 암석 시료의 임계하 균열성장 지수에 관한 연구

  • Received : 2019.04.22
  • Accepted : 2019.04.26
  • Published : 2019.04.30

Abstract

Subcritical crack growth in rock material can occur under monotonic and cyclic loading. Subcritical crack growth plays an important role in evaluating the long-term stability of structures in rocks. This paper presents the results of studies conducted to determine subcritical crack growth parameters under monotonic and cyclic loading in rock-like material. The constant stress rate method was employed for monotonic loading. The subcritical crack growth parameter of n under cyclic loading was determined by the relation between the rate of crack growth per cycle and stress intensity factor range. The specimens contained pre-existing flaws with 45 and 60 degrees of inclination angle and flaws spacing and continuity were varied to arrange crack growth in shear or tensile manner. The results show that the parameter of n is almost constant regardless of the applied load conditions such as monotonic and cyclic or shear and tension.

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Fig. 1. Schematic configuration of specimen geometry

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Fig. 2. Specimen geometry

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Fig. 3. Specimen geometry after crack growth

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Fig. 4. Schematic illustration of the crack model: (a) shear crack model; (b) sliding crack model

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Fig. 5. Results of constant stress rate tests under monotonic loading

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Fig. 6. Variation of the crack growth da/dN as a function of the stress intensity factor range ΔK

Table 1. Specimen geometry used in this study

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Table 2. Experiment results

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