SU587362A1 - Method of determining fracture toughness of construction materials - Google Patents

Description

The invention relates to mechanical testing of structural materials, and specifically to methods for testing the fracture toughness during crack propagation.

There is a known method for determining the sensitivity of high-strength materials to cracking under stretching, in which a sample with symmetrically arranged cracks is loaded until destruction jl.

The disadvantage of this method is its 10 low accuracy due to the different sizes of cracks on the opposite faces of the sample.

There is also a known method for determining in h. bone fracture of structural materials, which is that an eccentric tensile stress is applied to a flat 15 sample with a one-sided notch through a pair of holes symmetrically relative to the notch, and by the magnitude of the force corresponding to; 20 t viscosity of fracture 12

The disadvantage of this method is arising. when testing sheet materials of deplanation of a sample in the compression zone, n6 is yushi-25

with an eccentric extension, which leads to a distortion of the trajectory of the burrs and a decrease in the accuracy of the tests.

The purpose of the invention is to improve the accuracy of the method by eliminating the transfer of sheet samples.

The difference between the proposed method and the known one lies in the fact that in the compression zone of the specimen of breaking load an additional tensile load is applied through the second pair of holes symmetrically relative to the notch line.

The drawing shows the test scheme proposed by the method. , Sample 1 and 3 and 4 are attached to sample 1 on both sides of the notch line 2, to which forces from are applied. loading device. The force P is the main breaking force, and the force R. creates an additional tensile load in the compression zone from the breaking load,

Both rods 3 and 4 on one side of the sample can be fixed on one of the grips of the loading device, and the other two rods on the other side can be attached to a rim. In this case, the ratio of the main load and the additional remains constant during the test.

When a sample is loaded, the force that corresponds to the moment of crack propagation is judged on the viscosity of the material fracture.

Formula of invention

A method for determining the fracture toughness of structural materials, which consists in applying an eccentric tensile load to a flat specimen with an external neurez through a pair of holes, –– symmetrically relative to the notch, and

The strength of the force corresponding to the moment of crack propagation is judged by the fracture toughness, characterized in that, in order to increase the accuracy of the method by eliminating the deplanation of sheet specimens, an additional tensile load is applied in the compression zone of the specimen from the fracture load through the second pair of holes located symmetrically with respect to the notch line.

Sources of information taken into account in the examination;

1. Bel S, E, Method of determining the sensitivity of high-strength materials to

cracking upon stretching - Factory Lab, 1963, No. 9, p.1119-112

2, Brown, W., J. Strowley. Testing high-strength metallic materials for fracture toughness under plane strain. M ,, the World, .1972, p. 154-172.

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