Method and device for testing dynamic shear fracture toughness of brittle materials

Abstract

The invention discloses a method for testing the dynamic shear fracture toughness of brittle materials and an implementation device thereof. A cylindrical sample containing a prefabricated annular crack is installed on a Hopkins pressure bar dynamic experiment device, and an impact bullet is used to hit the incident The rod exerts dynamic shear force on both ends of the cylindrical sample with prefabricated cracks between the incident rod and the transmission rod. According to the measured strain value of the strain gauge on the incident rod and the transmission rod, the cross-sectional area of ​​the The modulus of elasticity of the compression bar and the value of the confining pressure of the sample are calculated according to the formula proposed by the present invention to obtain the dynamic shear fracture toughness K of the brittle material IIC and the corresponding load rate By using the method of the invention, the dynamic shear fracture toughness of the quasi-brittle material can be obtained, which fills up the blank in this research field.

Description

technical field [0001] The invention belongs to the field of performance testing of brittle materials, and in particular relates to a method for testing the dynamic shear fracture toughness of brittle materials by using a cylindrical sample designed with prefabricated cracks and an implementing device thereof. technical background [0002] The shear fracture toughness of brittle materials such as rock and concrete is a very important mechanical property of brittle materials. According to the documents retrieved by the inventor, the current measurement of the shear fracture toughness of brittle materials such as rocks and concrete is mostly performed on a material testing machine under static or quasi-static conditions. Tensile shear samples, etc. At the same time, there is an important problem in the above-mentioned shear fracture test, that is, the geometric configuration of the sample and the corresponding experimental loading conditions are difficult to avoid the additio...

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Problems solved by technology

At the same time, there is an important problem in the above-mentioned shear fracture test, that is, the geometric configuration of the sample and the corresponding experimental loading conditions are difficult to avoid the additional tensile stress component at the crack tip in the test. Shear fracture, the result is that the crack deviates from the original crack surface and expands, and the tensile stress has a great influence on the crack initiation

For the dynamic shear fracture toughness of brittle materials under high loading rate, due to the inertia effect caused by the stress wave and the stress singularity at the crack tip superimposed, due to the limitation of the current testing methods and methods, there has been no mature and feasible measurement method

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