SU1582066A1 - Method of determining damageability of material - Google Patents

Abstract

The invention relates to a testing technique and makes it possible to determine the accumulation of damage in materials during their testing. The purpose of the invention is to increase the information content by determining additional parameters of the characteristic stages of damage. The indenter is moved along the surface of the sample before loading, and the frequency of change in the force of its movement is recorded, the characteristic size of the structural elements of the material is determined, with account of which the speed and time of movement of the indenter are chosen. Then, in the process of loading the material sample, the indenter is additionally moved along its surface, the frequency of the force change of its movement is recorded, the dispersion of the frequency spectrum is determined, and according to the extreme values, the beginning and the end of the characteristic stages of material damage: formation of microcracks, macrocracks and main cracks are judged him 2 Il.

Description

The invention relates to a testing technique, and specifically to methods for determining damage in materials during their testing.

The purpose of the invention is to increase the information content by determining additional parameters of the characteristic stages of damage.

Fig. 1 shows the tribospectral characteristics of the sample surface of a material when tested by monotonic stretching. Figure 2 - the dependence of the dispersion parameter of the frequency spectrum in figure 1.

The method is carried out as follows. .

An indenter is moved along the surface of the sample material and the frequency of change in the force of its movement, i.e. obtain the tribospectral characteristics of the sample surface of the material prior to its loading. From the resulting frequency spectrum, the characteristic size of the structural elements of the material is determined, taking into account which the speed and time of movement of the indenter on the surface of the loaded material sample are chosen.

Load the sample material, for example, cyclic or monotonic stretching. In the process of loading, using the indenter, similarly to the previous one, tribospectral characteristics of the sample surface of the material are obtained at several levels of its loading, which are shown in Fig. 1, where Sr is the spectral plane value; Ј l macroplastic deformation; f is the frequency.

After stopping the loading of a sample of a material, the dispersion of the frequency spectrum is determined by the tribo-spectral characteristics of its surface, the extreme values of which determine the beginning and end of the characteristic stages of damage and the material that it undergoes during testing. Figure 2 shows the independence of the dispersion parameter Dy of the frequency spectrum from the macroplastic deformation parameter Ј „, .. DisD.

Percy DX, which is determined by the area under the spectral density curve S on Lig 1, is a sensitive parameter of spectral analysis. From a physical point of view, the dispersion IL characterizes inhomogeneous

strength of the strength properties of the surface layer of the sample material. The PL section corresponds to the hardening of the material, the LM section corresponds to the softening (loosening) of the surface5

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five

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A sample of the number of controlled structural elements, for example, 50, and the velocity V and the time t of movement of the indenter were chosen. After that, the tribospectral surface characteristics of the samples were determined at a selected velocity V over a selected time t and the dispersion Dx of the frequency spectrum was found.

The frequency of change of the movement force of the indenters was transformed into electrical signals by a mechatronic converter. The amplified signals are converted by a measuring system of the type 484/2 into machine codes, and spectral analysis was performed on an M4030 computer.

Samples were loaded by monotonic stretching on a VME-UTM installation under the same conditions at a temperature T 273K. Their tribospectral characteristics (figure 1) and dispersion of frequency spectra (figure 2) were determined; the extreme values of which in t. M, N, and K correspond to the initiation of microcracks, macrocracks, and trunk cracks in the material, respectively, and denote various stages of material damage.

Claims (1)

a lot of At the moment of loading, in accordance with the formula of the invention, branching m. M, the formation of microcracks occurs in the material. Section MN corresponds to the accumulation of microcracks in the material. T. N corresponds to the time of the beginning of the union of microcracks and the initiation of macrocracks. The NK region corresponds to the process of formation of macrocracks. T. K corresponds to the moment of the appearance of the main crack, and the section KO corresponds to the development of the main crack. THAT corresponds to the moment of destruction of the material sample. Example. Samples were cut out of the disk of the turbine 45 of the aviation GTE, the material of which is a heat-resistant alloy EI-698VD. Tribospectral surface characteristics of the samples were determined by scanning the surface 50 The method for determining the damageability of a material, which consists in loading a sample of a material, moving an indenter across its surface, and recording the frequency of the change in its movement force, which determines the damageability of the material, characterized in that, in order to increase the informativity, by determining additional parameters damage stages, additionally move the indenter over the sample surface prior to its loading, and record the frequency of the force change, according to the obtained frequency spectrum, The characteristic size of the structural elements of the material is taken into account, taking into account the speed and time of movement of the indenter over the surface of the loaded sample, and after the cessation of loading, the dispersion of the frequency spectrum is determined, the extreme values of which judge the beginning and end of the characteristic stages of material damage. a blunt diamond indenter that was inserted into a material with a strength of 300 N. The indenter moved at a speed of V 2.5 µm / s. The median frequency f of the tribospectral characteristic was determined. The characteristic size of 1 structural elements was calculated by the formula 1 V / 2fc. Statis Formula was invented The method for determining the damageability of a material, which consists in loading a sample of a material, moving an indenter across its surface, and recording the frequency of the change in its movement force, which determines the damageability of the material, characterized in that, in order to increase the informativity, by determining additional parameters damage stages, additionally move the indenter over the sample surface prior to its loading, and record the frequency of the force change, according to the obtained frequency spectrum, The characteristic size of the structural elements of the material is selected, taking into account the speed and time of movement of the indenter over the surface of the loaded sample, and after the termination of loading, the dispersion of the frequency spectrum is determined, the extreme values of which judge the beginning and end of the characteristic stages of material damage. 6 9.5 1.0 15 2.0 /, / & 1 Dx 0.015 2b%