Experimental study of the association between sandstone size effect and strain rate effect
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DOI 10.1007/s12206-020-0811-2
Journal of Mechanical Science and Technology 34 (9) 2020 Original Article DOI 10.1007/s12206-020-0811-2 Keywords: · Strain rate effect · Size effect · Sandstone · Split Hopkinson pressure bar (SHPB)
Correspondence to: Siming Kao [email protected]
Citation: Kao, S., Zhao, G., Xu, W., Cheng, X., Dong, C., Zhang, R. (2020). Experimental study of the association between sandstone size effect and strain rate effect. Journal of Mechanical Science and Technology 34 (9) (2020) 3597~3608. http://doi.org/10.1007/s12206-020-0811-2
Received July 15th, 2019 Revised
May 17th, 2020
Accepted July 4th, 2020
Experimental study of the association between sandstone size effect and strain rate effect Siming Kao, Guangming Zhao, Wensong Xu, Xiang Cheng, Chunliang Dong and Ruofei Zhang State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines, Anhui University of Science and Technology, Huainan 232001, China
Abstract
The association between sandstone size effect and strain rate effect were investigated experimentally with a split Hopkinson pressure bar (SHPB) system. The sandstone samples with Φ50 mm and different lengths were loaded under the constant ratio of punch velocity to sample length to study their size effects. Sandstone samples with constant length of 25 mm were taken as the reference to study their strain rate effects. Results indicate that, under the same velocity of the punch, strain rate of each sandstone sample is inversely proportional sample length; dynamic strength of sandstone increases with the strain rate and the length to diameter ratio (L/D), and presents a quadratic curvilinear relation with strain rate while presenting a cubic curvilinear relation with sample L/D; the reasonable L/D of Φ50 mm sandstone samples ranges from 0.5 to 0.8; that dissipated energy can present a fixed proportional relation with punch kinetic energy is unrelated to sample length.
† Recommended by Editor Chongdu Cho
1. Introduction
© The Korean Society of Mechanical Engineers and Springer-Verlag GmbH Germany, part of Springer Nature 2020
As a natural material, rock has microcracks and other defects inevitably. However, samples of certain sizes should be used to get reliable data in the rock mechanics experiment, and sample sizes in the metal material test should not be used any more. According to the rock dynamic test method and related suggestions, diameters of cylindrical rock samples should not be smaller than 50 mm [1]. In the SHPB test system, size effect and strain rate effect of samples have a bearing on material dynamic strength, and usually blended in the test [2, 3]. Many scholars have carried out early-stage studies on material strain rate effect and used technical means like wave shaper [4-7] and special-shaped punch [8-11], which ensure accuracy of test measurement. On cement [12], granite [13, 14], sandstone [10, 15-18] and other materials [19], the law of material strength increasing with the increase of loading strain rate has been obtained, and
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