Change in fracture toughness of rocks under moderate thermal effect

The article describes the laboratory-scale test data on fracture toughness of different genotype rocks under moderate thermal effect (to 100 °С). Samples of granite, limestone and marble with different size grains were tested. The samples were manufactured as beams with a length of 90 mm (L), width of 20 mm (b) and thickness of 10 mm (t); the parallel misalignment of the faces of the samples was not higher than 0.5% of the fitting linear size of a sample; the samples had a saw cut with a depth of 7 mm (h) and width not more than 1.2 mm (e) to simulate an edge crack in the middle of a sample. After all preparation stages, the samples were examined using ultrasonic defectoscopy to detect internal defects. The purpose-designed plant allowed heating of the test samples during three-point flexural tests. At the temperature from 20 to 80 °С, it was traced how the critical stress intensity factor (fracture toughness)–the characteristic of the fracture strength of materials–changed. The studies neglected the test results if the plane of the main crack in the samples deviated from the plane of the saw cut by 2 mm and more. For another thing, the results deviated from the arithmetic average by 30% were discarded as well. The investigation of the thermal field influence on the ability of samples to resist crack growth exhibited the decrease in this ability with the increasing temperature in all samples of all test types of rocks.

Keywords: strength characteristics, fracture, fracture toughness, normal tension crack, fracture toughness coefficient, moderate thermal effect, bending, three-point flexure, rocks.
For citation:

Vinnikov V. A., Pavlov I. A. Change in fracture toughness of rocks under moderate thermal effect. MIAB. Mining Inf. Anal. Bull. 2024;(3):5-16. [In Russ]. DOI: 10.25018/ 0236_1493_2024_3_0_5.

Acknowledgements:
Issue number: 3
Year: 2024
Page number: 5-16
ISBN: 0236-1493
UDK: 622.023.23+620.174.25+539.421.5
DOI: 10.25018/0236_1493_2024_3_0_5
Article receipt date: 18.12.2023
Date of review receipt: 27.01.2024
Date of the editorial board′s decision on the article′s publishing: 10.02.2024
About authors:

V.A. Vinnikov1, Dr. Sci. (Phys. Mathem.), Assistant Professor, Head of Chair, e-mail: evgeny.vinnikov@gmail.com, ORCID ID: 0000-0002-3011-053X,
I.A. Pavlov1, Graduate Student, e-mail: 3.14alekseevich@gmail.com, ORCID ID: 0009-0005-1011-9819,
1 University of Science and Technology MISIS, 119049, Moscow, Russia.

 

For contacts:

I.A. Pavlov, e-mail: 3.14alekseevich@gmail.com.

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