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Rock macroscopic fracture toughness calculation method based on nanoindentation technology

A nano-indentation and fracture toughness technology, applied in computing, computer parts, design optimization/simulation, etc., can solve problems such as inability to meet, discrete rock data, and difficulty in complete rock blocks, achieving less samples and lower costs. The effect of low cost and low requirements on specimen shape and size

Active Publication Date: 2021-02-12
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

Method used

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  • Rock macroscopic fracture toughness calculation method based on nanoindentation technology
  • Rock macroscopic fracture toughness calculation method based on nanoindentation technology
  • Rock macroscopic fracture toughness calculation method based on nanoindentation technology

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Embodiment Construction

[0048] The technical solutions of the present invention will be further described below in conjunction with specific examples.

[0049] A method for testing the macroscopic fracture toughness of rock based on nanoindentation technology, specifically comprising the following steps:

[0050](1) Combining the dot matrix method with nano-indentation technology to obtain the P-h curve of each test point inside the rock material, according to the P-h curve, use the O-P theory to calculate the micro-mechanical parameters (elastic modulus, stiffness and hardness, etc.) of the test point. The schematic diagram of the dot matrix method is as follows figure 1 As shown, the typical P-h curve obtained by the nanoindentation method 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] Where: P max is the maximum load at the indentation; ...

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Abstract

The invention discloses a method for testing macroscopic fracture toughness of rock based on a nanoindentation technology, which comprises the following steps of: 1, distinguishing phases with different mechanical properties in the rock by using a clustering analysis method after acquiring micromechanical parameters inside the rock based on the nanoindentation technology by using the characteristic that the nanoindentation test has low requirements on the shape and the size of a sample; 2, after the interaction among the particles in the rock is considered, upgrading the microscopic elastic modulus into the macroscopic elastic modulus by utilizing the Mori-Tanaka theory; 3, calculating the fracture energy release rate of each phase by using a fracture energy area method; and 4, regarding the fracture energy release rate of the weakest phase as the fracture energy release rate of the fracture surface, and calculating the macroscopic fracture toughness of the rock by combining the macroscopic elastic modulus and adopting the Griffith fracture theory. The invention provides a new test method and a new calculation method for testing the macroscopic fracture toughness of the rock, the related parameters of the fracture surface are measured by using a microcosmic test means, and then the fracture surface is transited 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 rocks based on nano-indentation technology, and belongs to the technical field of analytical instruments and material performance testing thereof. Background technique [0002] The 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 is one of the important mechanical parameters, which needs to be accurately measured. [0003] At present, the common test methods for macroscopic fracture toughness of rock mainly include the following categories: short round bar test, bending test with notched beam, central notched disc splitting test, and central notched semi-disc bending test. The above traditional rock macroscopic fracture toughness testing methods have the following disadvantages: (1) there are strict requirements ...

Claims

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Application Information

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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
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