A method for calculating macroscopic fracture toughness of rock based on nanoindentation technology
A nano-indentation and fracture toughness technology, applied in the direction of calculation, computer parts, design optimization/simulation, etc., can solve problems such as inability to meet, discrete rock data, and difficulty of complete rock blocks, and achieve the shape and size of the sample. The effect of low size requirements, low cost and few samples
Active Publication Date: 2022-07-22
CENT SOUTH UNIV
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Problems solved by technology
The above traditional rock macroscopic fracture toughness testing methods have the following drawbacks: (1) there are strict requirements on the shape and size of the sample; Difficulty; (3) The heterogeneity of the rock causes the data to be discrete, and a large number of experiments are required to obtain the average value
However, in some specific projects, such as deep sea mining, deep drilling, and moon mining, on the one hand, it is difficult to take out complete rock blocks, and on the other hand, the cost of sampling is extremely high, and it is difficult to take out samples to meet the current common macroscopic fracture toughness Test Requirements
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[0048] The technical solutions of the present invention will be further described below with reference to specific examples.
[0049] A method for testing the macroscopic fracture toughness of rock based on nanoindentation technology, which specifically includes the following steps:
[0050](1) Combine the lattice method and nanoindentation technology to obtain the P-h curve of each test point inside the rock material, and use the O-P theory to calculate the micromechanical parameters (elastic modulus, stiffness and hardness, etc.) of the test point according to the P-h curve. The schematic diagram of the dot matrix method is as follows figure 1 As shown, the typical P-h curve obtained by nanoindentation is as follows figure 2 shown.
[0051] The basic micromechanical parameters (elastic modulus E, hardness H and stiffness S) of each test point are calculated according to formula (1):
[0052]
[0053] In the formula: P max is the maximum load at the indentation; A is ...
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The invention discloses a method for testing the macroscopic fracture toughness of rock based on the nano-indentation technology. The nano-indentation test has low requirements on the shape and size of the sample, and the micro-mechanical parameters inside the rock are obtained based on the nano-indentation technology. , the first step uses the method of cluster analysis to distinguish the phases with different mechanical properties in the rock; the second step considers the interaction between the particles inside the rock, and uses the Mori-Tanaka theory to upgrade the microscopic elastic modulus to the macroscopic elastic modulus In the third step, the fracture energy release rate of each phase is calculated by the fracture energy area method; in the fourth step, the fracture energy release rate of the weakest phase is regarded as the fracture energy release rate of the fracture surface, and combined with the macroscopic elastic modulus, Grid The Fiss fracture theory calculates the macroscopic fracture toughness of rocks. The invention provides a new test method and calculation method for testing the macroscopic fracture toughness of rock, uses the microscopic test method to measure the relevant parameters of the fracture surface, and then transitions to the macroscopic level through the Griffith fracture theory.
Description
technical field [0001] The invention relates to a method for testing the macroscopic fracture toughness of rock based on nano-indentation technology, and belongs to the technical field of analytical instruments and material performance testing thereof. Background technique [0002] Fracture toughness of rock refers to the ability of rock to resist crack initiation and propagation. In rock engineering applications, such as hydraulic fracturing, the macroscopic fracture toughness of rock, as one of the important mechanical parameters, needs to be accurately determined. [0003] At present, the common rock macroscopic fracture toughness test methods mainly include the following categories: short round bar test, bending test with grooved beam, center grooved disk splitting test, and center grooved half-disk bending test. The above traditional rock macroscopic fracture toughness testing methods have the following disadvantages: (1) There are strict requirements on the shape and ...
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IPC IPC(8): G06F30/20G06K9/62G06F119/14
CPCG06F30/20G06F2119/14G06F18/23213G06F18/24
Inventor 蔡鑫周子龙芮艺超雷博翔赵聪聪张升
Owner CENT SOUTH UNIV