GOST R 56664-2015

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  ГОСТ Р 56664-2015

GOST R 56664−2015 nondestructive testing. Determination of the stress state of material of engineering products of customroot methods. General requirements

GOST R 56664−2015
Group Т59

NATIONAL STANDARD OF THE RUSSIAN FEDERATION

Nondestructive testing

DETERMINATION OF THE STRESS STATE OF MATERIAL OF ENGINEERING PRODUCTS OF METHODS CUSTOMROOT

General requirements

Non-destructive testing. Evaluation of stress state material engineering products by acoustoelastic methods. General requirements

OKS 77.040.10

Date of introduction 2016−07−01

Preface

1 DEVELOPED by the Open joint-stock company «Scientific-research center of control and diagnostics of technical systems» (JSC «NIC KD») with the participation of Nizhny Novgorod state technical University n.a.R.E.Alekseev (NSTU them.R.E.Alekseeva)

2 SUBMITTED by the Technical Committee for standardization TC 132 «Technical diagnostics"

3 APPROVED AND put INTO EFFECT by the Federal Agency for technical regulation and Metrology, dated 22 Oct 2015 N 1615-St

4 INTRODUCED FOR THE FIRST TIME

Application rules of this standard are established in GOST R 1.0−2012 (section 8). Information about the changes to this standard is published in the annual (as of January 1 of the current year) reference index «National standards» and the official text changes and amendments — in monthly information index «National standards» In case of revision (replacement) or cancellation of this standard a notification will be published in the upcoming issue of the monthly information index «National standards». Relevant information, notification and lyrics are also posted in the information system of General use — on the official website of the Federal Agency for technical regulation and Metrology on the Internet (www.gost.ru)

Introduction

An objective assessment of the health and safety of operating responsible of technical objects is impossible without the assessment of the stress state, which is their material.

In a huge number of practically important cases, estimation of the stress state of a technical object is possible only at the stage of starting operation, immediately after manufacture. To evaluate the stress state of the material of the object during its operation is usually possible only by the method of lines (and in most cases destructive) measurements.

One of the most promising methods for measuring mechanical stresses in the material without its destruction is an acoustic method based on provocations effect — the linear dependence of the velocity of propagation of elastic waves from stresses reliable experimental determination which ensured thanks to modern measurement technology.

Existing national standards governing the use of acoustic method in problems of control of the stress state on the General requirements to measurement and the procedures for the preparation and measurements contained in them is incomplete.

This standard was developed in order to provide methodological basis for wide application of the acoustoelasticity method for determining one — and biaxial stress state of the material responsible of the technical facilities in the process of their manufacture and testing and in actual operation.

1 Scope

This standard applies to the acoustic method of determining the stress state of material of engineering products with the use of the acoustoelasticity method.

This standard specifies the basic requirements for the procedure of determining the one — and biaxial stress state of the material technical objects, having two plane-parallel surfaces in the measurement area, with the use of bulk longitudinal and transverse waves propagating normal to the surface of a technical object.

Established by this standard method can be applied both in laboratory research and bench and full-scale conditions control the stress state of the material of a wide class of technical objects.

2 Normative references

This standard uses the regulatory references to the following standards:

GOST 7.32−2001 System of standards on information, librarianship and publishing. The report on research work. The structure and rules of registration

GOST 12.1.001−89 System safety standards. Ultrasound. General safety requirements

GOST 12.1.004−91 System safety standards. Fire safety. General requirements

GOST 12.1.038−82 standards System of labor safety. Electrical safety. The maximum permissible values of the touch voltage and currents

GOST 12.2.003−91 System safety standards. Equipment production. General safety requirements

GOST 12.2.013.0−91 System safety standards. Machines manual electric. General safety requirements and test methods

GOST 12.3.002−75 System safety standards. The process of production. General safety requirements

GOST 1497−84 (ISO 6892−84) Metals. Test methods tensile

GOST 2768−84 Acetone. Specifications

GOST 2789−73 surface Roughness. Parameters and characteristics

GOST 6616−94 thermoelectric Converters. General specifications

GOST 10587−84 epoxy-Dianova uncured. Specifications

GOST 17299−78 ethyl Alcohol technical. Specifications

GOST 28840−90 Machine for testing materials in tension, compression and bending. General technical requirements

GOST R 8.563−2009 State system for ensuring the uniformity of measurements. Techniques (methods) of measurements

GOST R 12.1.019−2009 System of standards of occupational safety. Electrical safety. General requirements and nomenclature of types of protection

GOST R 52731−2007 nondestructive testing. Acoustic method of control of mechanical stresses. General requirements

GOST R 55043−2012 nondestructive testing. Determination of the coefficients of elastic-acoustic coupling. General requirements

GOST R 55725−2013 nondestructive testing. Piezoelectric ultrasonic transducers. General technical requirements

GOST R ISO 5725−2-2002 Accuracy (trueness and precision) of methods and measurement results. Part 2. The basic method for the determination of repeatability and reproducibility of a standard measurement method

Note — When using this standard appropriate to test the effect of reference standards in the information system of General use — on the official website of the Federal Agency for technical regulation and Metrology on the Internet or in the annual information index «National standards» published as on January 1 of the current year, and the editions of the monthly information index «National standards» for the current year. If replaced with a reference standard, which was given an undated reference, then it is recommended to use the current version of this standard, taking into account all enabled in this version modifications. If replaced with a reference standard, which is given a dated reference, it is recommended to use the version of this standard referred to above by year of approval (acceptance). If after approval of this standard in the reference standard, which is given a dated reference, a change affecting a provision to which reference, the provision is recommended to be applied without taking into account this change. If the reference standard is cancelled without replacement, the position in which reference is made to him, recommended to be used in part not affecting this link.

3 Symbols and abbreviations

3.1 this standard applies the following conventions:

h — thickness of the material of the test object, mm;

V — velocity of propagation of an elastic wave with wave vector in the idirection with polarization vector directed to the direction (the values i=Kcorrespond to longitudinal waves, the values of the cross), m/s;

t — pulse delay of the elastic wave propagating with the velocity V, NS;

 — customplugin the rate coefficients, 1/MPa;

 — customplugin coefficients of delay, 1/MPa;

 — effective frequency of the ultrasonic pulses, MHz;

 — yield strength of the object material, MPa;

,  — the principal stresses acting in the object material, MPa;

T — temperature of the test object in the measurement area in the absence of stress, °C;

T — temperature of the test object in the measurement area by the action of stress, °C;

V — the speed of propagation of longitudinal elastic waves in the object material, m/s;

V — velocity of propagation of elastic shear waves in the object material, m/s;

m — the number of the reflected pulse transverse elastic waves, polarized in the direction of the texture material;

m — the number of the reflected pulse transverse elastic waves, polarized in the direction perpendicular to the texture material;

t — the number of the reflected pulse of longitudinal elastic waves;

n — the number of repetitions in determining the pulse delay of the elastic transverse waves, polarized in the direction of the texture of the material, under the action of stress;

n — the number of repetitions in determining the pulse delay of the elastic transverse waves, polarized in the direction perpendicular to the texture of the material, under the action of stress;

n — the number of repetitions in determining the pulse delay of the elastic longitudinal waves under the action of stress;

T (m) — the duration of the sweep that renders mthe reflected pulses of transverse elastic waves, polarized in the direction of the texture of the material, ISS;

T (m) — the duration of the sweep that renders mthe reflected pulses of transverse elastic waves, polarized in the direction perpendicular to the texture of the material, ISS;

T(m) — the duration of the sweep that renders m the reflected pulses of longitudinal elastic waves, MS;

 — maximum permissible absolute error of measurement of time intervals of the used measuring instruments NS;

 — maximum permissible relative error of measurement of time intervals of the used measuring instruments;

 — delays of the reflected pulses transverse wave numbers of the MTrelative to the first reflected pulse when the polarization of the wave in the direction of texture of the material in the absence of voltage after nrepeated measurements, HC, i=1… n;

t — average delay of the reflected pulse transverse wave number mrelative to the first reflected pulse when the polarization of the wave in the direction of texture of the material in the absence of stress, NS;

the variation coefficient values ;

 — delays of the reflected pulses of shear waves with numbers mwith respect to the first reflected pulse when the polarization direction of the texture of the material under the action of stresses after nrepeated measurements, HC, i=1… n;

t — average delay of the reflected pulse transverse wave number mrelative to the first reflected pulse when the polarization of the wave in the direction of texture of the material under the action of stresses, NS;

the variation coefficient values ;

 — the value of the delay t, normalized to 20 °C, NS;

 — the value of the delay t, normalized to 20 °C, NS;

 — delays of the reflected pulses of shear waves with numbers mwith respect to the first reflected pulse when the polarization of the wave in the direction perpendicular to the texture of the material, after nrepeated measurements, HC, i=1… n;

t — average delay of the reflected pulse transverse wave number mrelative to the first reflected pulse when the polarization of the wave in the direction perpendicular to the texture of the material, in the absence of voltage after nrepeated measurements, NS;

the variation coefficient values ;

 — delays of the reflected pulses of shear waves with numbers mwith respect to the first reflected pulse when the polarization of the wave in the direction perpendicular to the texture of the material, under the action of stresses after nrepeated measurements, HC, i=1… n ;

t — the average value of the reflected pulse transverse wave number mrelative to the first reflected pulse when the polarization of the wave in the direction perpendicular to the texture of the material, under the action of stresses, NS;

the variation coefficient values ;

 — the value of the delay t, normalized to 20 °C, NS;

 — the value of the delay t, normalized to 20 °C, NS;

 — delays of the reflected pulses of longitudinal waves with numbers mwith respect to the first reflected pulse in the absence of voltage after nrepeated measurements, HC, i=1… n;

t — the average value of the reflected pulse of longitudinal wave number mrelative to the first reflected pulse in the absence of stress, NS;

the variation coefficient values ;

 — delays of the reflected pulses of longitudinal waves c rooms m relative to the first reflected pulse by the action of stresses after nrepeated measurements, HC,i=1… n;

t — average delay of the reflected pulse of longitudinal wave number mrelative to the first reflected pulse by the action of stress, NS;

the variation coefficient values ;

 — the value of the delay t, normalized to 20 °C, NS;

 — the value of the delay t, normalized to 20 °C, NS;

, , ,  — customplugin coefficients, 1/MPa;

k, k, k, k — provocations (strain) coefficients, MPa;

k, k  — thermo-acoustic coefficients, 1/deg:

kis the relative change in the velocity of longitudinal elastic waves when the temperature changes by 1 degree;

k — the same as for transverse waves.

3.2 this standard applies the following abbreviations:

OK — the object of control;

NA — stress state;

SI — measurement means;

Wee — ultrasonic pulse;

EAP — electro-acoustic transducer;

PEP — piezoelectric Converter;

EMAT — electromagnetoelasticity Converter;

COIS — coefficients provocational connection.

4 General provisions

4.1 Measuring voltage at the control performed using customroot in accordance with the General requirements of GOST R 52731.

4.2 the Direction of wave propagation perpendicular to the plane of action of the measured voltages.

4.3 sounding Scheme of the material corresponds to the echo method of ultrasonic testing. Method of excitation of elastic vibrations — with or without contact depending on the EAP. The recommended form of the radiated signal is «pulse» with a high-frequency (ultrasonic) filling the envelope smooth and effective duration (at the level of 0.6 of the maximum amplitude) 2 to 4 periods of the fundamental frequency.

4.4 Radiation and reception of acoustic signals is carried out using a transceiver (combined) EAP longitudinal and transverse waves.

Note — as EAP can be used in probes according to GOST R 55725 or specially designed EMAT.

4.5 Measured strains are the volume average of the ultrasonic beam, determined by the transverse dimensions of the EAP and the thickness of the material. As a rule, the principal stresses in the plane perpendicular to the direction of wave propagation. The stress values are those values which correspond to the initial values of acoustic parameters measured before the onset of stress.

4.6 the present approaches to the control of mechanical stresses in the material by the acoustic method are usually based on common ratios of customproperty [1]-[3].

The relevant equations relating velocity and time of propagation of elastic body waves with different polarizations with the existing stresses within the matrix theory of customroot in the absence of external heat and electromagnetic radiation have the usual linear relations of the form:

, (1)

, (2)

where , is the stress tensor at the time of measurement and the tensor of initial stresses, respectively;

, is the relative speed change and the time of propagation of elastic waves:

, (3)

, (4)

where V and tcorrespond to voltage , and starting voltage .

In the absence of initial stress of equation (1), (2) take the form:

, (5)

.(6)

4.7 Engineering methods of control of stress using the most popular acoustic echo-pulse method are usually based on measurements of time intervals between the repeatedly reflected pulses of elastic waves of different polarization. In this regard, customplugin the ratio of type (6) are more preferred.

4.8 the Most rigorous approach to building engineering correlations customroot based on the measurement of time intervals is proposed in [4], where the basic equations (5) for the case of plane, the national Assembly of the principal stresses , in the plane perpendicular to the direction of propagation of elastic waves, the expressions connecting stress with delays of pulses of elastic waves of two types: longitudinal and transverse polarized along the principal stresses.

4.9 Material of the majority of engineering products can be considered as orthotropic. If the axis of anisotropy of the material considered directed along the axes of Cartesian coordinates x and u, respectively, the wave vector for the bulk waves will be in the direction to coincide with the z-axis. The main stress — longitudinal and transverse  — lie in the plane z=0 and directed along the axes x and u, respectively.

4.10 Formula to calculate and are of the form:

,(7)

,(8)

where , , , , , .

Strain [3] or provocations [4] the coefficients are calculated by the formulas:

, (9)

, (10)

, (11)

. (12)

Included in the formulas (9)-(12) the parameters , , , are expressed through customplugin coefficients as follows:

, (13)

, (14)

, (15)

, (16)

4.11 In the case when the material is OK in accordance with GOST R 52731 is acoustically isotropic for customplugin of the coefficients of the equalities:

, (17)

. (18)

4.12 Strain gauge (provocations) coefficients for acoustically isotropic material are calculated by the formulas:

, (19)

, (20)

4.13 Strain coefficients (COIS) used to calculate stresses from the measured acoustic delays must be defined with a maximum relative error of ±10%. Experimental determination of CWAS carried out in accordance with the requirements of GOST 55043 and Annex A of this standard.

4.14 Formula to calculate and in the case of an acoustically isotropic material take the form:

,(21)

.(22)

4.15 the Effect of temperature on the measurement results of the biaxial stresses into account by using thermo-acoustic coefficients, the procedure for determining which is given in Appendix B.

4.16 Recommended in this standard method can serve as the basis for the drafting of methods of measurements GOST R 8.563.

4.17 In the development of techniques of measurements must be verified on the basis of the representative database tested OK.

5 safety Requirements

5.1 measurements of the national Assembly allow operators with skills of equipment operation ultrasonic inspection, able to use national and industry normative and technical documents on the acoustic control techniques, trained to work with used C and are certified for knowledge of safety regulations in the relevant sector of industry.

5.2 in determining HC, the operator should be guided by GOST 12.1.001, GOST 12.2.003, GOST 12.3.002 and rules of technical safety for operation of electrical consumers according to GOST R 12.1.019 and GOST 12.1.038.

5.3 Measurement is carried out in accordance with the safety requirements specified in the operating instructions of the equipment, part of the used SI.

5.4 Facilities for measurements shall meet the requirements [5] and [6].

5.5 In the organization of work definition NA OK must be met fire safety requirements according to GOST 12.1.004.

6 Requirements for measuring instruments

6.1 as SI can be used installing collected from production equipment, and specialized instruments to determine time intervals between the repeatedly reflected UI, propagating in the material is OK, certified and verified in the prescribed manner.

6.2 SI needs to provide the measurement of the echo method using the UI with a smooth envelope.

6.3 SI needs to provide the possibility of radiation and reception of UI with an effective rate of 2.5 to 10 MHz.

6.4 In the set SI must enter direct combined or separated-combined EAP, which provides radiation and reception of pulses of longitudinal and transverse elastic waves propagating normal to the surface OK.

Note — as a direct probe of the combined shear waves can be used converters Panametrics (USA).

6.5 Documentation the SI shall contain the measurement procedure and the documents that establish:

— the purpose and scope SI;

— the composition and main characteristics of the hardware and software, including error of measurement of the parameters of the UI;

— methods and means of achieving the compatibility of SI, including data, electrical, energy, software, development, and operational.

6.6 description of the functionality of SI in the operational, engineering and programme documents should reflect the specifications of the hardware and software.

6.7 Operational characteristics of the SI must conform to the requirements of the specifications and of this standard.

6.8 Requirements for software of measuring instruments

6.8.1 Software SI shall provide the possibility of selecting any of the reflected UI and search for the required sampling points of the profile of pulses.

6.8.2 Software must consider the conditions of carrying out acoustic measurements on «OK», in particular temperature.

6.8.3 Primary acoustic information for each point of measurement should always be stored on external media, protected from unauthorized access.

6.9 Ancillary devices and materials

6.9.1 the Thermocouple surface type TPP TPP 10 or 13 according to GOST 6616 for measuring the surface temperature TD.

6.9.2 When using probes needed:

grinding tool for surface preparation according to GOST 12.2.013.3;

— degreasing liquid (alcohol according to GOST 17299 or acetone GOST 2768) for surface preparation;

— contact liquid.

7 Requirements for building control

7.1 the Thickness of the material is OK at the measuring points of the national Assembly shall not be less than 2 mm.

7.2 Before installation of the EAP surface cleaned of dirt, scale, rust and degreased.

7.3 the Class of surface roughness at the point of measurements using the probe is not lower thanRa 2,5 (GOST 2789).

Note — When using the probe method does not provide the required accuracy of the determination of the national Assembly, if the surface roughness OK Ra exceeds 2.5 µm according to GOST 2789.

7.4 Distance from the measuring point to weld OK — at least twice the thickness of the material OK.

7.5 When using the probe the viscosity of the contact liquid at the temperature of measurement should correspond to the viscosity of the epoxy resin at a temperature of 25 °C from 12 to 25 PA·s (GOST 10587).

7.6 Additional factors influencing the accuracy of measurements of the NA

7.6.1 roughness of the inner (reflecting) surface or the presence of thin solid coating layer.

7.6.2 Significant volumetric heterogeneity of the material in the area of testing, leading to dispersion of elastic waves and their additional attenuation.

7.6.3 Additional reflecting surface due to stratification of material in the field of testing (the presence of flat defects of the base metal).

7.6.4 characteristics of the factors referred to in 7.6.1−7.6.3, not determined quantitatively. Their combined impact is assessed according to the characteristics of the reflected acoustic pulses with the requirements of this standard.

8 preparation for measurement

8.1 Study certificates for the material is OK.

8.2 On the basis of technical documentation on «OK «to determine values of h at the measurement points.

8.3 On the basis of reference data or experimentally determine the values Vand V.

8.4 Choose EAP, which depends on h has the following values:

— 10 MHz at h of 2 to 3 mm;

— 5 MHz at h from 3 to 10 mm;

— 2.5 MHz when h more than 10 mm.

8.5 Identify the location of the measuring points.

8.6 the state of the surface at selected points in compliance with the conditions of measurement (see 7.2−7.3).

8.7 is Applied, if necessary, the layer of contact liquid on the prepared surface OK.

8.8 Install EAP on the surface OK, connect their SI.

8.9 Include SI, check its performance when displaying video device timebase of the received signals.

8.10 On the screen of a monitor device without any visible distortion shall be observed repeatedly reflected to the TOU.

8.11 Verify the absence on the time scan additional pulses are caused by either having to measure additional reflecting surfaces (valid for operating conditions OK defect layers, inclusions, etc., detected by ultrasonic flaw detection), or wrong orientation of the transducer transverse vibrations relative to the axes of symmetry of the material OK.

8.12 calculate the minimum value of the scan, providing visualization of the required number of the reflected UI and measure the delay with a given relative error by the formula:

,(23)

where t — hardware delay of the probe pulse, µs, defined by the technical characteristics of the used SI.

Typically, the value should not exceed 10.

8.13 Get the waveforms of signals when using EAP transverse elastic waves, polarized in the direction of the texture material, the value of the sweep T.

Note — For an isotropic material under biaxial NS EAP establish the direction of polarization along .

8.14 Estimate the ratio of the amplitude of UI with number mto the average of the noise level. If this ratio exceeds 10 dB, the measurements with a given relative error is considered possible.

8.15 If the ratio «signal-noise» to depth with a number mless than 10 dB, then successively reduce the value of mper unit as long as the value of the ratio «signal to noise» will not be more than 10 dB.

8.16 Calculated actual relative error of determining the delay of UI according to the formula:

, (24)

and then make a decision about carrying out measurements with a reduced compared to the error or replace SI for more accurate, ensuring the fulfillment of the relationship:

.(25)

8.17 Measurement 8.13−8.16 repeat for the transducer transverse elastic waves, polarized in the direction perpendicular to the texture of the material, determining an acceptable value of the number of reflected UI m, while the actual relative error in determining the delay of UI calculated by the formula:

. (26)

Measurements 8.18 8.13−8.16 repeat for the transducer of longitudinal elastic waves, determining an acceptable value of the number of reflected UI m , the actual relative error in determining the delay of UI calculated by the formula:

. (27)

Note — set out in 8.1 to 8.18 of the preparation for the measurement is the same for OK with the current stresses in their absence.

9 the procedures for measuring and processing the results

9.1 determination of the biaxial stress state

9.1.1 use the contact thermometer to measure surface temperature OK in the absence of stresses , MT.

9.1.2 In accordance with the user manual SI are measuring delays of transverse elastic waves, polarized along the texture of the material is OK (or along the actions of the main voltage ) , with the reinstallation of EAP. The number of repetitions nmust be at least 5.

Note — generally the smallest error in the measurement of delay provides a method of signal transfer through zero [7].

9.1.3 Validation of correlation reference points

9.1.3.1 Calculate the difference between the delay for the reflected depth with a number mand a delay of the second reflected UI relative to the first.

9.1.3.2 Check the validity of the relationship:

. (28)

9.1.3.3 subject to the relations (28) perform steps 9.1.4.

9.1.3.4 failure to comply With the ratio (28) calculate the value k according to the formula:

, (29)

where . The icon [ ] indicates the rounding operation.

9.1.3.5 In further calculations instead of the values using the adjusted values of the delays are equal .

The test of correlation of the reference points is carried out for waves of all types.

9.1.4 an Array of values to check for outliers in accordance with GOST R ISO 5725−2.

9.1.5 After reducing (in the presence of outliers), the values nfor further calculations use a truncated variational series.

9.1.6 Determine the values of tand a by the formulas:

, (30)

. (31)

9.1.7 Checking the condition:

. (32)

9.1.8 If the condition (32) in the further calculations using the value of tobtained in 9.1.6.

9.1.9 If the condition (32) is not fulfilled, a second measurement with a larger number n.

9.1.10 If the increase in the number of measurements ndoes not lead to fulfillment of the conditions (32) adopt the decision on the further measurements with reduced accuracy.

9.1.11 Measuring and processing at 9.1.3−9.1.10 conducted for EAP transverse elastic waves, polarized in the direction perpendicular to the texture of the material is OK (or the actions along principal stress ):

, (33)

. (34)

9.1.12 Measurements and their processing for 9.1.3−9.1.10 EAP is carried out for longitudinal elastic waves. At the same time determine the values of tand a by the formulas:

, (35)

, (36)

9.1.13 Expect delays given by the formulae:

, (37)

, (38)

. (39)

9.1.14 using a contact thermometer to measure surface temperatures OK under the action of stresses T.

9.1.15 Measurements and their processing for 9.1.3−9.1.14 hold OK under the action of stresses.

9.1.16 Shows the delay calculated by the formulas:

, (40)

, (41)

. (42)

9.1.17 Voltage and for each point of measurement is calculated according to the formulas:

, (43)

, (44)

where , , *, *, , .
___________________
* Formulas correspond to the original. — Note the manufacturer’s database.

9.2 Definition the uniaxial stress state

9.2.1 Under the action of uniaxial stress along the texture of the material the voltage is calculated by the formula:

, (45)

where .

9.2.2 Under the action of uniaxial stress across the texture of the material the voltage is calculated by the formula:

, (46)

where .

10 Rules for registration of measurement results

10.1 the results of the measurements are fixed in the Protocol, the form of which is given in Appendix V.

10.2 If the measurement of the NA OK are part of the research work, the measurement should be made in accordance with the requirements of GOST 7.32.

Annex a (mandatory). Definition provocations coefficients

Appendix A
(required)

A. 1 Provocations coefficients determined by conducting tensile tests on flat samples according to GOST 1497.

A. 2 Use two types of samples:

— longitudinal cut from the material parallel to the structure;

— a cross-cut from the material perpendicular to the texture.

A. 3 using the PEP class of surface roughness of samples at the point of measurement is not lower than Ra 2,5 according to GOST 2789.

A. 4 For loading sample use of machines for mechanical testing of materials according to GOST 28840.

A. 5 Selection of test equipment is carried out so that the sample to create tension component .

A. 6 the Testing machine must provide the necessary load with an acceptable voltage deviation not more than 1 MPa during the period of time required to conduct acoustic measurements (from 30 seconds to several minutes depending on the skill of the operator and used by the SI).

A. 7 form the step of loading the sample from the initial load corresponding to the value of uniaxial tension not more , to load corresponding . It is recommended to provide at least five levels of loading for the subsequent regression analysis of test results.

A. 8 Sample with the attached EAP put into the machine for mechanical tests, achieve proper alignment and attached to it a small load to ensure reliable fixation of the specimen in the grips.

9 A. At each step of loading are measuring delays of the three types of UI:

t — delay MS for shear wave, polarized along the axis of loading;

t — delay MS for shear wave, polarized perpendicular to the axis of loading;

t — delay MS for longitudinal waves.

Measurements are conducted with increasing and decreasing load. Then the specimen is removed from the car. Each loading (up-down) is carried out three times. Before the new loading EAP remove and re-install on the sample.

A. 10 Conduct regression dependency handling , ,

where , , t, t, t — delay UI in the material of the specimen without load.

A. 11 Customplugin coefficients determined in the following way:

equal to the tangent of the angle of inclination to the axis of the regression lines for the longitudinal samples;

equal to the tangent of the angle of inclination to the axis of the regression lines for the longitudinal samples;

equal to the tangent of the angle of inclination to the axis of the regression line for control samples;

equal to the tangent of the angle of inclination to the axis of the regression line for control samples.

A. 12 Strain (provocations) coefficients are calculated according to formulas:

, , , . (A. 1)

Appendix B (mandatory). Determination of thermo-acoustic coefficients

Appendix B
(required)

B. 1 Definition of thermoacoustic coefficients k(k, k) is performed on the basis of the study of regression dependences of the delays of pulses of elastic waves of respective types ton temperature T of the standard model.

B. 2 measurement of the temperature dependences is carried out on standard samples of the material OK in the laboratory.

B. 3 the surface Temperature of the sample is measured using a thermoelectric Converter according to GOST 6616.

B. 4 the Sample is heated to a temperature of 80 °C, then for a uniform temperature distribution maintained at room temperature until they cool down to 60 °C.

B. 5 as the cooling of the sample at intervals of 5 °C is performed a measurement of the surface temperature of the sample Tand the corresponding delays for each i the values of the temperature.

B. 6 Thermoacoustic coefficients calculated by the formula:

, (B. 1)

where ,

Nis the total number of measurements for a given sample.

Measure repeat for 3−5 samples averaged results.

Annex b (recommended). Form of measurement Protocol

The App
(recommended)

«CLAIM"
Head
(name of organization)
(signature)			(initials, surname)
»	»		20		G.
PROTOCOL
determine the stress state of the object control method of customroot
(technical object, a controlled phase of a technical object)
The name of the object of control
Number (or code) of the targeted area
Material grade
Strain gauge (provocations) coefficients, MPa
k	k	k						k
Thermoacoustic coefficients, 1/deg
k		k
The surface temperature of the test object, without the stress T(°C)
The surface temperature of the test object under the action of stress T(°C)
Timeout values for the object material without stress, NS
t
t
t
Timeout values for a measuring point stress of the material object of the control, NS
t
t
t
Stress values, MPa
Date of control
Surname, initials of the operator
Note

Bibliography

[1]	GUZ A. N., Makhort F. G., Gushcha O. I. Introduction to customproject. Kiev: Naukova Dumka, 1977. — 162 p.
[2]	Bobrenko, V. M., Vangheli, M. S., Kutsenko A. N. Acoustic tensometry. Chisinau: Shtiintsa, 1991. — 204 p
[3]	Nondestructive testing: Handbook: In 7 t./Under the editorship of V. V. Klyuev. Vol. 4. KN.1. V. A. Anisimov, B. I. Katorgin, A. N. Kutsenko, V. P. Malakhov, A. S. Rudakov, V. K. Chvanov. Acoustic strain measurement M.: Mashinostroenie, 2004. — 226 p
[4]	Nikitina N. E. Customproject. Experience of practical application. N. Novgorod: TALAM, 2005. — 208 p.
[5]	SNiP 2.09.03−85 Construction of industrial enterprises. Design standards
[6]	SanPiN 2.2.½.1.1.1200−03 Sanitary-protective zones and sanitary classification of enterprises, constructions and other objects
[7]	MVI. Standard samples of time of passage of ultrasonic signals. The determination of basic metrological characteristics. IMP UB RAS, Ekaterinburg, 2007. 16 p.

UDC 620.172.1:620.179.16:006.354	OKS 77.040.10	Т59
Key words: mechanical stress, acoustic echo method, customroot, anisotropy, delayed pulses, strain gauge (provocations) coefficients

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