RU2193772C1 - Procedure predicting residual service life of steel structures - Google Patents

Abstract

FIELD: analysis of state of steel structures of mechanical systems, mining machines, in particular. SUBSTANCE: according to procedure residual service life of steel structures is achieved by determination of spectral density, temporary tensile strength, yield point, relative reduction and elongation, friction angle of structural inhomogeneities of natural roughness. Standardized spectra of resonance are determined in five ranges of response frequencies of acoustoemission radiation: ultrasonic oscillations of subgrain in range 62,7-19.1 kHz, oscillations of shear- detachment in range 2.7-1.9 kHz, modulating relaxation twinning oscillations in range 432-82 Hz, modulating relaxation oscillations of structural hardening in range 50.2- 17.85 Hz and modulating relaxation oscillations of infrafrequency in range 4.6-4.2 Hz. All mentioned physical and mechanical parameters are established for moment of total degradation of metal and for time T_i, of measurement, then residual service life ΔT_п, is found by certain formula that includes recorded time of usage and values of diameters of metal subgrains. EFFECT: prediction of residual service life without any repeated measurements. 2 cl, 1 dwg

Description

 The invention relates to the field of non-destructive testing of steel metal structures by analyzing the responses of acoustic emission of metal from mechanical systems to predict the residual life, including mining machines.

 A known method for predicting the residual life of steel metal structures of mechanical systems, including mining machines, using non-destructive testing of the response of acoustic emission radiation, including determining the spectral density of reference signals compared with the spectral density of signals at the time of measurement (see, for example, RF patent 1237915, cl G 01 N 29/10, publ. 1986).

 The disadvantage of this solution is the need for reference spectra for all available elements of mechanical systems made of different grades of metal, for various welded joints, as well as their degradation spectra, which is almost impossible.

 The closest analogue to the technical solution, the prototype, is a method for predicting the residual life of steel metal structures of mechanical systems by means of non-destructive testing of the response of acoustic emission radiation, including determining the spectral density and reference physical and mechanical parameters of the metal, including the tensile strength, tensile strength, and elongation and narrowing, the angle of friction (see RF patent 2020476, CL G 01 N 29/14, publ. 1994).

 A significant drawback of this known solution is that the forecast analysis requires periodic repeated measurements, for example, after a month, a year, etc., thereby replacing the reference parameters with the current ones determined in the previous measurement. This is due to the peculiarities of the operation of the metal structures of many mechanical systems, for example, mining machines, which, as a rule, are repaired without fixing the time of the start of operation, the repair grade of the metal, the carbon equivalent of the used electrodes and other parameters.

 The objective of the invention is to enable prediction of the residual life without periodically re-measuring parameters, which allows you to pre-schedule the repair or replacement of worn-out equipment and ensure continuous and efficient operation of the facility.

где d*_сз.i - диаметр субзерна на момент замеров;
d*_сз.д - диаметр деградированного субзерна;
d*_сз.э - диаметр эталонного субзерна.The essence of the invention lies in the fact that in the method for predicting the residual life of steel metal structures of mechanical systems, including mining machines, by means of non-destructive testing of the response of acoustic emission radiation, including determining the spectral density and reference physical and mechanical parameters of the metal, including the temporary tensile strength , yield strength, elongation and contraction, friction angle of structural inhomogeneities of natural roughness, is additionally determined The spectra of the following resonances are recorded in five frequency ranges of the response of acoustic emission radiation: ultrasonic vibrations of a subgrain in the range 62.7-19.1 kHz, shear-separation vibrations in the range 2.7-1.9 kHz, modulating relaxation twinning oscillations in the range 434-82 Hz, modulating relaxation vibrations of structural hardening in the range of 50.2-17.85 Hz and modulating relaxation vibrations of infrared frequency in the range of 4.6-4.2 Hz to determine and analyze physicomechanical parameters at the time of operation, the moment of measurement and at the degree of complete degradation of the metal, and the diameter of the degraded grain d * _s.d is determined by the formula
d * _s.d = 6 • d * _s.e ,
where d * _ze - the diameter of the reference grain;
and for a fixed operating time T _{i of the} mechanical system, that is, at the time of measurements, the residual life ΔT _{p is} determined by the formula

where d * _sz.i is the diameter of the subgrain at the time of measurement;
d * _sz.d - diameter of the degraded subgrain;
d * _sz.e - diameter of the reference subgrain.

где ψ_су - относительное сужение;
δ_уд - относительное удлинение;
16^o - угол трения адсорбировавшейся влаги в межзеренных протоках стали при рН 6-8;
диаметр эталонного зерна d*_з.э определяют по формуле

где σ_в - временнoй предел прочности при растяжении;
σ_т - предел текучести,
а диаметр субзерна d*_cз определяют из формулы

где f_узк.-сз - частота излучения ультразвуковой энергии субзерном в диапазоне 62,7-19,1 кГц;
С*_др - скорость дрейфа тепловой энергии.In addition, the friction angle of structural heterogeneities of natural roughness ρ ^* can be determined by the formula

where ψ _sou is a relative narrowing;
δ _beats - elongation;
16 ^o - the angle of friction of adsorbed moisture in the intergranular ducts of steel at pH 6-8;
the diameter of the reference grain d * _ze is determined by the formula

where σ _in - temporary tensile strength;
σ _t - yield strength,
and the diameter of the subgrain d * _cz is determined from the formula

where f _narrow.-sz - the frequency of ultrasonic radiation by a subgrain in the range of 62.7-19.1 kHz;
C * _dr - thermal energy drift velocity.

Кроме того, угол трения структурных неоднородностей естественных шероховатостей ρ^* и диаметр эталонного зерна d*_з.э могут быть определены по формулам

а диаметр субзерна d*_сз может быть определен из формулы

Наличие указанных отличительных признаков подтверждает соответствие предложенного способа критерию "изобретательский уровень".Compared with the prototype (2020476), the invention contains distinctive features, which further determine the spectra of the following resonances at five frequency ranges of the response of acoustic emission: ultrasonic vibrations of the subgrain in the range 62.7-19.1 kHz, shear-separation vibrations in the range 2.7-1.9 kHz, modulating relaxation twinning vibrations in the range 434-82 Hz, modulating relaxation vibrations of structural hardening in the range of 50.2-17.85 Hz and modulating relaxation vibrations of the infrared frequency in in the range of 4.6-4.2 Hz for determining and analyzing the physicomechanical parameters at the time of commencement of operation, the moment of measurement, and at the time of complete degradation of the metal, the diameter of the degraded grain d * _w is determined by the formula
d * _s.d = 6 • d * _s.e ,
and for a fixed operating time T _{i of the} mechanical system, that is, at the time of measurement, determine the residual life ΔT _p by the formula

In addition, the friction angle of structural inhomogeneities of natural roughnesses ρ ^* and the diameter of the reference grain d * _s.e can be determined by the formulas

and the diameter of the subgrain d * _sz can be determined from the formula

The presence of these distinctive features confirms the compliance of the proposed method with the criterion of "inventive step".

The invention is illustrated by the drawing, which shows a graph of the analysis of the displacements of the resonances of the responses of acoustic emission depending on the diameter of the subgrain d * _sz , mm.

In the drawing are indicated:
1 - change in ultrasonic vibrations;
2 - change in shear-separation oscillations;
3 - change in the frequency of modulating relaxation twinning oscillations;
4 - change in the frequency of modulating relaxation vibrations of structural hardening;
5 - change in modulating relaxation infra-frequency;
6 - the moment the product was put into operation, i.e. T ₀ = 0;
7 - a fixed point in time of operation T _i ;
8 - full resource T _r .

For clarity, the dimension of the grain diameter d * _sz on the graph is given in microns (μm).

 The method is carried out in three stages as follows.

 To implement the method, the well-known method of non-destructive testing of the response of acoustic emission radiation due to the artificial excitation of atoms and molecules of the metal structure using known devices, as well as experimental and calculated data, are used.

The first stage is analyzed and determined according to the manufacturer's certificate reference physicomechanical parameters metal steel metallokontsruktsy mechanical systems, including: temporal tensile strength - σ _B, MPa; yield strength - σ _t , MPa; elongation - δ _beats ,%; relative narrowing - ψ _su ,%; bulk density - ρ _op , kg / m ³ and the longitudinal speed of sound - С * _L , m / s.

где 16^o - угол трения адсорбировавшейся влаги в межзеренных протоках стали при рН 6-8 (определен именно для стали в лабораторных условиях).The friction angle of structural inhomogeneities of natural roughness ρ ^* is determined by the formula

where 16 ^o is the angle of friction of adsorbed moisture in the intergranular ducts of steel at pH 6-8 (determined specifically for steel in laboratory conditions).

по О.А. Берман-И.А. Воронцовой.Reference Grain Diameter

by O.A. Berman-I.A. Vorontsova.

The analysis of physical and mechanical parameters makes it possible to determine the frequencies of the spectral density of acoustic emission radiation, which are given in Table. 1, from which it follows that they are interconnected with the diameter of the subgrain d * _sz.e (in calculations, the dimension d * _{sz is} taken in meters).

 Tab. 1 contains the relationships of physicomechanical parameters obtained by experimental and calculation methods based on known dependences during plane deformation with resonant frequencies of the response spectrum of acoustic emission radiation by A. V. Berman and D. V. Berman (see RF patent 2127349, class E 21 C 25/38).

According to the table 1, the following physical and mechanical parameters can be determined (depending on the value of ρ ^* ):
d * _sz is the diameter of the subgrain, the dimension for clarity is given in mm (the subgrain is a combination of a certain number of pairs of plates of cementite and ferrite with a thickness inherent in this structure);
C * _dr - thermal energy drift velocity, m / s;
f _narrow-sz - the frequency of radiation of ultrasonic energy by a subgrain in the range of 62.7-19.1 kHz (ultrasonic vibrations);
f _sd-o - response of the shear-separation frequency in the range of 2.7-1.9 kHz (shear-separation oscillations);
f _Mr - response modulating relaxation frequency of twinning oscillations in the range 434-82 kHz;
f _ms is the response of the modulating relaxation frequency of structural hardening oscillations in the range of 50.2-17.82 Hz;
f _mv - modulating relaxation infra-frequency in the range of 4.6-4.2 Hz;
l _Mon - the perimeter of surface tension during plane deformation, m

Определяют также эталонное значение динамической вязкости μ_эт по формуле
μ_эт = 0,499•l^*•ρ_ОП•C $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ , МПa•c,
где l^* - длина магистральной трещины в конце ее ускоренного развития по Пэрису-Лейбову Б.М. определяется по формуле

где σ $\genfrac{}{}{0ex}{}{\text{*}}{\text{П}}$ - коэффициент Пауссона, который в момент сдвига-отрыва по А.Н. Зеленину равен 0,52 (кн. А.Н. Зеленин "Основы разрушения грунтов механическими способами", М., 1968 г., стр. 375), а по И.А. Биргеру и Я.Г. Пановко "Прочность, устойчивость, колебания". М. 1968 г., больше 0,5.The value of f _narrow-sz can also be determined by the formula

The reference value of the dynamic viscosity μ _{et is} also determined by the formula
μ _et = 0.499 • l ^* • ρ _OD • C $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ , MPa • s,
where l ^* is the length of the main crack at the end of its accelerated development according to Paris-Leibov B.M. determined by the formula

where σ $\genfrac{}{}{0ex}{}{\text{*}}{\text{P}}$ - Pausson coefficient, which at the moment of shear-separation according to A.N. Zelenin is equal to 0.52 (Prince A.N. Zelenin "Fundamentals of soil destruction by mechanical means", Moscow, 1968, p. 375), and according to I.A. Birgeru and Ya.G. Panovko "Strength, stability, vibrations". M. 1968, more than 0.5.

The turbulization coefficient R _p * at α = 90 ^° is 0.5.

 Further, to speed up the calculations, the data are summarized in table. 2 (obtained experimentally and computationally using known dependencies).

The intensity vector of the tensile stress tensor from the intensity ellipsoid, which reflects the combination of the vector of the spherical tensor of the hydrostatistical pressure and the stress deviator vector at an angle between them of 90 ^o and an angle of inclination of the shear-separation elements φ = 90 ^°, denote T * _e-90 .

Далее определяют модуль динамической упругости по В. В. Присташу: E $\genfrac{}{}{0ex}{}{\text{*}}{\text{g}}$ = 1,0555•ρ_ОП•C $\genfrac{}{}{0ex}{}{\text{*2}}{\text{L}}$ , ГПa; спектральную плотность энергии поглощения при накоплении малоцикловой усталости по В.М. Берману: ω_из.э = τ_сд-о.эт•f_сд-о.эт; ГПа/с; энергоемкость разрушения, формируемую релаксационно-модулируюшей инфрачастотой, по Р.М. Штейнцайгу, Г.Я. Воронкову и А.В. Берману:

(журнал "Открытые горные породы", 1999, стр. 65-68); спектральную плотность освобождаемой энергии в устье усталостной трещины по А.А. Гриффиту и Дж. Р. Ирвину, равную интегралу И.Р. Райса, то есть J_1C-f = H_w.мв•l_пн, МДж/м², и эталонную трещиностойкость стали

в момент Т₀=0 установки изделия на эксплуатацию.The coefficient of metomorphism according to T.I. Berman - K * _mm and the strain rate coefficient - dV *, m / s, with a maximum energy angle α ^* = 45 ^* + 0.5ρ ^* according to E.Z. Pozin (EZ Pozin "Coal Resistance to Tool Destruction", Moscow, 1972, p. 450); the width of the plastic zone is dn * in a plane stress state (in meters). These parameters, depending on d * _sz, determine the reference minimum shear-separation stress according to A.V. Berman, i.e.

Next, determine the modulus of dynamic elasticity according to V.V. Pristash: E $\genfrac{}{}{0ex}{}{\text{*}}{\text{g}}$ = 1,0555 • ρ _OD • C $\genfrac{}{}{0ex}{}{\text{* 2}}{\text{L}}$ , GPa; spectral energy density of absorption during the accumulation of low-cycle fatigue according to V.M. Berman: ω _iz = τ _sd-o.et • f _sd-o.et ; GPa / s; fracture energy intensity, formed by relaxation-modulating infra-frequency, according to R.M. Steinzaigu, G.Ya. Voronkov and A.V. Berman:

(magazine "Open rocks", 1999, p. 65-68); spectral density of released energy at the mouth of a fatigue crack according to A.A. Griffith and J.R. Irwin, equal to the integral of I.R. Rice, that is, J _1C-f = H _w.mv • l _mon , MJ / m ² , and the reference crack resistance of steel

at the moment T ₀ = 0 the installation of the product for operation.

At the second stage, after determining the reference parameters, the physicomechanical parameters of the completely degraded metal of steel metal structures are determined using the table. 1 and 2 and the physical dependencies described above, with a sub-grain diameter d * _szd = 0.043295 mm (see table 2), i.e., with a dimensional grain of a degraded structure, according to the formula d * _zd = 6 • d * _s .

а для определения относительного сужения ψ_су-д полностью деградированного металла стали используют зависимость ψ_су-д = ψ_э•K_μ-ψ, где

при этом относительное удлинение δ_уд-д = 0,2867794•ψ_су-д = ψ_су-д/tgρ_о.д.
Резонансы на ультразвуковой частоте и на других частотах, т.е. f_{узк.сз-д}, f_сд-о.д, f_мр.д, f_мс.д и f_мв.д определяют по табл. 2.To determine the yield strength σ _{etc of a} fully degraded steel metal, use the dependence σ _etc = k _t-sd • τ _sd-od , where the transition coefficient

and to determine the relative narrowing ψ _{su-d of a} completely degraded steel metal, use the dependence ψ _su-d = ψ _e • K _μ-ψ , where

in this case, the elongation δ _beats-d = 0.2867794 • ψ _su-d = ψ _su-d / tgρ _od
Resonances at the ultrasonic frequency and at other frequencies, i.e. f _{narrow szd} , f _sd-od , f _md , f _msd and f _{md are} determined from the table. 2.

где μ_д - динамическая вязкость деградированного металла;
ω_{из-д =} - спектральная плотность энергии поглощения, ГПа/с;
l_пн - периметр поверхностного натяжения при плоской деформации, м (табл. 1).The calculation of the coefficient of crack resistance K _{1s-f.d is} performed according to the formula

where μ _d is the dynamic viscosity of the degraded metal;
ω _{of d =} - the spectral density of the absorption energy, GPa / s;
l _Mon - the perimeter of surface tension during plane deformation, m (table. 1).

The above formulas are based on the fact that at the time of complete degradation of the metal, the longitudinal velocity of sound C * _Ld decreases and becomes equal to the transverse velocity of sound C * _s . _{Et of the} reference metal. Therefore, knowing the value of C * _s.et = 0.637 • C * _L according to G.M. Avchyan, it is possible to determine the value of C * _Ld = C * _s . _Et , m / s.

Then, in the third stage, i.e. during the operation of the mechanical system, when reference parameters and parameters at the time of complete metal degradation have already been determined, physicomechanical parameters are determined at a fixed operating time, i.e. at the time of measurements T _i using the formulas of the second stage.

During operation, the following parameters are experimentally determined at the time of measurement:
f _narrow.sz.i - ultrasonic frequency of radiation;
f _sd-o.i is the resonant shear-separation frequency, Hz;
f _Mr.i - relaxation modulating twinning frequency, Hz;
f _mc.i - advertising modulating sliding frequency of screw dislocations, Hz;
f _mv.i - relaxation modulating infra-frequency, Hz.

According to these parameters, that is, with fivefold duplication by the interconnected frequencies, the subgrain value d * _{sz.i is determined} for a fixed moment of operation time T _i (according to Table 1), and from it all the physical and mechanical parameters of the metal according to similar formulas of the second stage of the method (see drawing).

 Thus, the invention contains three stages of analysis of studies and calculations that determine the standard physical and mechanical parameters of the metal, similar parameters at the time of its complete degradation and for a fixed operating time, i.e. at the time of measurements.

где T_i - фиксированное время эксплуатации;
d*_сз.i - диаметр субзерна на момент замеров;
d*_сз.д - диаметр деградированного субзерна;
d*_сз.э - диаметр эталонного субзерна.At the end of these stages of research and calculations, the forecast of residual life is determined by the formula

where T _i - fixed operating time;
d * _sz.i - the diameter of the subgrain at the time of measurement;
d * _sz.d - diameter of the degraded subgrain;
d * _sz.e - diameter of the reference subgrain.

The total resource T _p metal product is
T _p = ΔT _p + T _i .
The value of ΔT _p can be in months, years, cycles, etc. depending on the dimension T _i .

 Below is an example of calculating the forecast of the residual life of low-alloy structural steel grade 16GS for welded metal structures of excavators (type of delivery: rolled sheet with a thickness of 40 mm).

 The calculation is carried out in three stages on the basis of the certificate of the manufacturer and according to the formulas described above.

 The calculation data are summarized in table. 3.

Для измерения различных частот могут быть использованы известные приборы, например "Шумомер-анализатор спектра SVAN-912АЕ" польской фирмы "Свантек", изготавливаемый по японской лицензии. Этот прибор воспринимает амплитуды в динамическом диапазоне 146 децибел конденсаторными микрофонами, например, типа SV-02-1/2 при чувствительности 50 мВ/Па при 200 В поляризационного напряжения, обеспечивая частотный диапазон 2 Гц-20 кГц, что удовлетворяет всем требованиям проведения прецензионных звуковых измерений.Having determined all the necessary parameters, we determine the residual resource by the formula:

Known instruments can be used to measure various frequencies, for example, the SVAN-912AE Sound Level Analyzer Spectrum of the Polish company Svantek, manufactured under a Japanese license. This device perceives amplitudes in the dynamic range of 146 decibels by condenser microphones, for example, of type SV-02-1 / 2 at a sensitivity of 50 mV / Pa at 200 V of polarizing voltage, providing a frequency range of 2 Hz-20 kHz, which meets all the requirements for precision audio measurements.

 It is also possible to use sound level meters and vibration analyzers of the Danish company Bruhl and Kier.

 To more accurately determine the diameter of the subgrain at the time of measurement, depending on the spectrum of the resonant frequencies of the acoustic emission radiation, the graph shown in the drawing can be used.

From the graph it follows that the resonances of the reference spectrum shift in frequency (decrease) at the time of measurement and then shift (decrease) to the value of degradation, which determines the diameter of the degraded subgrain d * _szd .

By identifying the area from the reference frequencies at a zero operating time up to the time T _i (measurement time) with the magnitude of the change in the diameter of the subgrain d * _sz , the predicted residual life time from T _i to T _d (residual life time) is identified with the change from d * _sz.i to d * _sz.d , as a result of which ΔT _{p is} determined, i.e. residual life forecast.

 EFFECT: invention allows to exclude repeated measurements and practically reliably determine the residual resource, which provides, on the one hand, a long-term forecast of the residual resource, on the other hand, timely preparation for repair, repair and replacement of operating equipment, prevents downtime and increases the efficiency of the facility.

Claims (3)

1. A method for predicting the residual life of steel metal structures of mechanical systems, such as mining machines, by non-destructive testing of the response of acoustic emission radiation, including determining the spectral density and reference physical and mechanical parameters of steel, including the temporary tensile strength, tensile strength, yield strength, elongation and narrowing , the friction angle of structural heterogeneities of natural roughness, characterized in that the reference spectra are further determined as follows resonances at five frequency ranges of the response of acoustic emission radiation: ultrasonic vibrations of the subgrain in the range of 62.7-19.1 kHz, shear-separation vibrations in the range of 2.7-1.9 kHz, modulating relaxation twinning oscillations in the range of 432-82 Hz, modulating relaxation vibrations of structural hardening in the range of 50.2-17.85 Hz and modulating relaxation vibrations of infrared frequency in the range of 4.6-4.2 Hz, as well as all the indicated physical and mechanical parameters at the time of complete metal degradation and at the time of measurement T _i and then defined dissolved residual resource ΔT _n in formula

where, d * _sz.i is the diameter of the subgrain at the time of measurement;
d * _sz.d. - diameter of the degraded subgrain;
d * _sz.e. - the diameter of the reference subgrain. 2. The method according to p. 1, characterized in that the diameter of the degraded grain d * _ze is determined by the formula
d * _w = 6 • d * _sz.e. ,
where d * _ze is the diameter of the reference grain. 3. The method according to p. 1 or 2, characterized in that the friction angle of the structural inhomogeneities of the natural roughness ρ ^* is determined by the formula

where ψ _sou is a relative narrowing;
δ _beats - elongation. 16 ^o - the angle of friction of adsorbed moisture in the intergranular ducts of steel at pH 6-8;
diameter of the reference grain d * _ze determined by the formula

where σ _in - temporary tensile strength;
σ _t - yield strength, and the diameter of the subgrain d * _s.z. determined from the formula

where f _UKS.-NW - the frequency of ultrasonic energy emission by a subgrain in the range of 62.7-19.1 kHz;
C * _dr - thermal energy drift velocity.

Images