The flattened Brazilian disc specimen used for testing elastic modulus, tensile strength and fracture toughness of brittle rocks; analytical and numerical results
The flattened Brazilian disc specimen used for testing elastic modulus, tensile strength and fracture toughness of brittle rocks; analytical and numerical results
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DOI：
10.1016/s1365-1609(03)00093-5
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发表时间：
2004-02
影响因子：
7.2
通讯作者：
Q.Z Wang;X.M Jia;S. Kou;Z.X Zhang;P. Lindqvist
中科院分区：
文献类型：
--
作者：
Q.Z Wang;X.M Jia;S. Kou;Z.X Zhang;P. Lindqvist
本文提出了用巴西圆盘试样一次测定脆性岩石的弹性模量E、抗拉强度σ t和张开型断裂韧度KIC的方法。本文对这些公式进行了理论分析，并给出了解析和数值结果。根据应力分析结果和Griffith强度准则，为了保证试样中心处裂纹萌生（这对试验的有效性至关重要），对应于平端宽度的加载角必须大于一个临界值（2α <$20 °）。分析表明，根据所记录的试件完整的载荷-位移曲线（曲线应包括最大载荷后的“波动”段），E可由最大载荷前的截面斜率确定，σ t由最大载荷确定，KIC由紧接在最大载荷后的局部最小载荷确定。导出了E、σt、KIC的计算公式，并对公式中的关键系数进行了有限元分析标定。此外，还给出了基于弹性力学的近似闭合公式，并与有限元结果进行了比较，结果表明其精度是足够的。
The flattened Brazilian disc specimen is proposed for determination of the elastic modulus E, tensile strength σtand opening mode fracture toughness KICfor brittle rocks in just one test. This paper is concerned with the theoretical analysis as well as analytical and numerical results for the formulas. According to the results of stress analysis and Griffith's strength criteria, in order to guarantee crack initiation at the centre of the specimen, which is considered to be crucial for the test validity, the loading angle corresponding to the flat end width must be greater than a critical value (2α⩾20°). The analysis shows that, based on the recorded complete load–displacement curve of the specimen (the curve should include the ‘fluctuation’ section after the maximum load), E can be determined by the slope of the section before the maximum load, σtby the maximum load, and KICby the local minimum load immediately subsequent to the maximum load. The relevant formulas for the calculation of E, σt, KICare obtained, and the key coefficients in these formulas are calibrated by finite-element analysis. In addition, some approximate closed-form formulas based on elasticity are provided, and their accuracy is shown to be adequate by comparison with the finite-element results.