Testing method for dynamic crack arrest toughness of I-type crack under middle-low speed impact load

Abstract

The invention discloses a testing method for dynamic crack arrest toughness of an I-type crack under a middle-low speed impact load, and belongs to the technical field of rock and concrete engineering. A test piece is a V-shaped side open single crack half-bordered test piece designed by an inventor. The test piece has a V-shaped bottom boundary, and generates an oblique-upward compression wave under an impact load, and the horizontal component of the compression wave has a compression effect on an expansion crack, thereby further preventing cracking of the expansion crack. The testing methodadopts a middle-low speed drop hammer impact test device, finite element difference software AUTODYN is used for simulation calculation, and results are basically consistent with test results. An obtained load stress time history curve is inputted into finite element program ABAQUS, and a time-history curve of a dynamic stress intensity factor of the I-type crack is obtained. Finally, the dynamiccrack arrest toughness of a material is determined by the crack arrest time of the crack. The testing method for the dynamic crack arrest toughness of the pure I-type crack under the middle-low speedimpact load has the advantages of simple test piece configuration, easy processing, simple and clear test procedure and convenient operation, and is suitable for the research of crack dynamic expansion behaviors and dynamic fracture toughness tests.

Description

technical field [0001] The invention belongs to the technical field of rock and concrete engineering, and in particular relates to the research on the test method of dynamic arrest toughness of type I cracks under medium and low speed impact loads. Background technique [0002] There are a large number of defects such as joints and cracks in brittle materials such as rocks and concrete, among which cracks are also one of the main defects that most scholars pay attention to. Under the action of impact load, the crack will expand and destroy, and then cause the instability and destruction of the whole structure. Therefore, the propagation behavior of crack propagation speed, propagation distance and propagation direction under dynamic load is one of the important topics that need to be solved urgently in the current rock dynamics research, and it is also a very important basic research. [0003] In terms of experiments, scholars have also adopted various loading methods for d...

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Problems solved by technology

[0004] At present, domestic and foreign research on the dynamic fracture behavior of rocks under impact loading mainly focuses on the crack initiation and expansion stages. Although some progress has been made in the research on the crack arrest stage, it is not yet mature, especially on the dynamic fracture behavior of rocks under medium and low speed loading. Research

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