GOST R 52731-2007

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  ГОСТ Р 52731-2007

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

GOST R 52731−2007

Group Т59

NATIONAL STANDARD OF THE RUSSIAN FEDERATION

Nondestructive testing

ACOUSTIC METHOD OF CONTROL OF MECHANICAL STRESSES

General requirements

Non-destructive testing. Stress evaluation by ultrasound. General requirements

OKS 77.040.10

Date of introduction 2007−10−0

Preface

The objectives and principles of standardization in the Russian Federation established by the Federal law of 27 December 2002 N 184-FZ «On technical regulation», and rules for the application of national standards of the Russian Federation — GOST R 1.0−2004"Standardization in the Russian Federation. The main provisions"

Data on standard

1 DEVELOPED by the Nizhny Novgorod branch of the Institute of mechanical engineering of the Academy of Sciences of the Russian Federation (NF IMASH) and Open joint stock company «Scientific-research center of control and diagnostics of technical systems» (OAO «nits KD»)

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 of June 28, 2007 N 153rd St

4 INTRODUCED FOR THE FIRST TIME


Information about the changes to this standard is published in the annually published index «National standards», and the text changes and amendments — in monthly indexes published information «National standards». In case of revision (replacement) or cancellation of this standard a notification will be published in a 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

Introduction

An objective assessment of the health and safety of operating responsible of the technical object in most practically important cases, is impossible without evaluation of the stress state, which is its material.

Among modern non-destructive methods of measurement of mechanical stresses and acoustic methods are among the most promising and increasingly used in the world.

In using acoustic methods for determining the stress state lies provocations effect — the linear dependence of elastic wave velocities, stress, a reliable experimental determination of which has become possible with the advent of modern ultrasonic and electronic measuring equipment.

This standard will serve as a methodological basis of the method of acoustic strain gauges for a wide class of engineering problems requiring rapid assessment of the stress state of the material in part responsible of technical objects.

1 Scope

This standard applies to acoustic echo method for determining one — and biaxial stresses in the plane perpendicular to the direction of wave propagation for isotropic and anisotropic materials, the directions of principal stresses which coincide with the axes of symmetry (including the sheet metal where the stresses acting along and across the rolled).

The standard does not apply to the determination of residual stresses arising in irreversible changes of the material due to heat treatment, plastic deformation, fatigue damage accumulation, etc.

This standard specifies the basic requirements for the procedure of determining the mechanical stresses averaged over the thickness of the material and the square of the ultrasonic beam in the material of technical objects using the method of acoustic strain gauges in laboratory and in field conditions, during commissioning and operation.

2 Normative references

This standard uses the regulatory references to the following standards:

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

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

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 published annually by the information sign «National standards» published as on January 1 of the current year and related information published monthly indexes published in the current year. If the reference standard is replaced (changed), when using this standard should be guided by replacing (amended) standard. If the reference standard is cancelled without replacement, then the situation in which the given link applies to the extent that does not affect this link.

3 Symbols and abbreviations

3.1 this standard applies the following designations:

, — the principal stresses in the plane, MPa;

 — pulse delay of elastic shear wave with the polarization vector parallel to the voltage in the charged material, ISS;

 — pulse delay of elastic shear wave with the polarization vector parallel to the voltage in the unloaded material;

 — pulse delay of elastic shear wave with the polarization vector parallel to the voltage in the charged material, ISS;

 — pulse delay of elastic shear wave with the polarization vector parallel to the voltage in the unloaded material;

 — pulse delay of elastic longitudinal waves in a loaded material, ISS;

 — pulse delay of the elastic longitudinal wave in the unloaded material;

 — intrinsic acoustic anisotropy of the material, calculated by the formula ;

, , are the coefficients kostopoulou communication, 1/MPa:

 — the relative change in the pulse delay of the shear wave, polarized along the direction of the uniaxial stress, if it is changed to 1 MPa;

 — the relative change in the pulse delay of the shear wave polarized transversely to the direction of the uniaxial stress, if it is changed to 1 MPa;

 — relative change of the delay pulse longitudinal waves when the voltage of 1 MPa;

, are the coefficients of provocations when connecting the voltage change of acoustic parameters for waves polarized along and across of his actions (respectively), and longitudinal waves, MPa;

 — the temperature of the object of control without load, °C;

 — the temperature of the test object under load, °C;

,  — thermoacoustic coefficients, 1/deg:

 — the relative change in the pulse delay of the shear wave when the temperature changes by 1 °C,

 — relative change of the delay pulse longitudinal waves when the temperature of

s to 1 °C.

3.2 this standard applies the following abbreviations:

NA — stress state;

OK — the object of control;

SI — measurement means;

EAP — electro-acoustic transducer.

4 Requirements to safety of works

4.1 measurements and processing of their results allow operators with skills in the operation of equipment of ultrasonic nondestructive testing, 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.

4.2 When carrying out works on determination of mechanical stresses by the acoustic method, the operator should be guided by GOST 12.1.001, GOST 12.2.003, GOST 12.3.002 pravilami of technical safety for operation of electrical installations* approved by Gosenergonadzor.
_______________
* There are «Interbranch Rules on labor protection (safety rules) for electrical installations» (SWEAT P M-016−2001, RD 153−34.0−03.150−00). — Note the manufacturer’s database.

4.3 Work should be carried out in accordance with the safety requirements set out in the instruction manual of equipment, part of the used measuring instruments.

4.4 the methodology of acoustic measurements for a specific OK must be specify the requirements with which compliance is mandatory when working in the enterprise.

4.5 In organization of work control must be complied with fire safety requirements according to GOST 12.1.004.

5 Requirements for measuring instruments

5.1 as SI can be used installing collected from production equipment, and specialized instruments for determining the stresses that are certified and verified in the prescribed manner.

5.2 SI should contain the set of EAP, providing radiation and reception of shear and longitudinal elastic waves.

5.3 requirements on the allowed error C

On the basis of information about the value of the coefficient kostopoulou connection material OK used SI for which permissible absolute error of measurement of delay satisfies the condition

, (1)

where and metrological supply;

 — the maximum value of the absolute error of measurement of delay , calculated according to the formula

, (2)

where is the absolute error of determination of coefficient kostopoulou connection ;

permissible absolute error of voltage measurement;

 — yield strength of the material.

5.4 Requirements for software of measuring instruments

5.4.1 Algorithmic part of the software should provide the calculation of the acoustic parameters with an accuracy in accordance with 5.2.

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

5.4.3 Primary acoustic information for each zone of control must reside on external media, protected from unauthorized access.

5.5 Requirements to methodological support of the measurement means

5.5.1 Methodological support SI must 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 rules on measurement error of delay pulses;

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

rules of aggregation of hardware and software and their interaction.

5.5.2 description of the functionality of SI in the operational, design and policy documents OK and C should reflect the specifications of the hardware and software.

6 requirements for the test object

6.1 OK in the areas of measurement should not include macro defects detected by nondestructive methods.

6.2 surface Condition in the areas of measurements should provide the necessary sensitivity and stability of measuring delays of the acoustic pulses.

6.3 Minimum thickness of material in the zone of measurement is determined by the pulse duration and the maximum attenuation of elastic waves and the condition of the reflecting surface.

6.4 the Minimum radius of curvature and the degree of not parallel surfaces of the subassembly in the measuring area is determined depending on the maximum permissible error of measurement of the latencies.

6.5 When the examination is OK with curved surfaces are more preferable for measuring the surface are of the convex type.

7 preparation for the inspection

7.1 Preparation for control includes the following main stages:

— analysis of technical documents and preparation of survey map;

— preparation of areas of measurement.

7.2 the Order of analysis of technical documents and mapping surveys

7.2.1 based On the study of technical documents for the object set:

the thickness of the material is OK in the areas of measurement voltages;

— the possibility of responsible nodes or elements of the structure of unwanted stress affecting their performance;

— calculated values of loads which the structure undergoes on purpose (balancing, displacement of one relative to the other parts, etc.);

— any other information causing the need for voltage control;

— brand material, mode of heat treatment, yield strength;

— ability to change the temperature of the structural element by more than 10 °C — 20 °C simultaneously with the change in voltages.

Note — in the absence of information about the material OK, it is allowed to identify its mechanical characteristics by results of specially conducted chemical analysis. When possible, experimentally evaluate the yield stress of the material OK.

7.2.2 On the basis of the analysis carried out in accordance with 7.2.1, and subject to the requirements of section 5 maps acoustic control object.

7.3 preparation of the object for acoustic measurements

7.3.1 In the areas of control must be prepared in flat areas with dimensions greater than the corresponding geometrical dimensions of the used EAP.

7.3.2 Surface prepared plots in the areas of measurement of mechanical treatment is adjusted to the degree of roughness and waviness, which provides the value of random error of measurement of delay , not exceeding the margin of error, calculated by formula (2).

7.3.3 Area measurements number and bring in a map of acoustic control.

8 Procedure control

8.1 measurement of the unloaded object

8.1.1 In the case of biaxial material HC OK measure and log acoustic control the temperature OK in control areas .

8.1.2 depending on the type of HC in control areas take measurements of the delay , (uniaxial, NS) or latency , , (biaxial NS).

8.1.3 8.1.2 Measurement is repeated 3−5 times.

8.1.4 Evaluate the random error in determining the delay and compare it with the allowable error, providing the required accuracy of determining the stresses.

8.1.5 If necessary, increase the number of repetitions as long as the random error in determining the delay will not be comparable with acceptable error.

Note — If you can reduce the measurement error of the delay to the maximum permissible values of the issue of the termination of the measurement or holding with the received error.

8.1.6 the Averaged measurement results of delay and to calculate the anisotropy log monitoring is given in Appendix A.

8.2 Measurements on the loaded object

8.2.1 In case of two NS measure and log acoustic control the temperature OK in control areas .

8.2.2 depending on the form of HC in control areas take measurements of the delay , (uniaxial, NS) or latency , , (biaxial NS).

8.2.3 Measurement is carried out in accordance with 8.1.3 to 8.1.5.

8.2.4 the Averaged measurement results of the delay log control.

9 Rules for processing results of the control

9.1 the Values of stresses acting in mutually perpendicular directions 1 and 2 of the structural element, calculated by the formulas:

; (3)

, (4)

where , the coefficients provocational connection, material of construction, calculated on the basis of known or experimentally measured , that :

; (5)

. (6)

9.2 If according to preliminary data it is known that the structural element can experience only uniaxial stress in the plane perpendicular to the direction of wave propagation, it can be calculated by the simplified formula:

(7)

either

, (8)

where  — coefficient provocations relationships for a uniaxial stress state.

9.3 In the case when , differ little (for the basic structural materials, it means the difference is more than 1.5% -2%), of the formula (7), (8) can be written as:

; (9)

, (10)

where is the parameter of acoustic anisotropy of strained material, calculated by the formula

. (11)

Note — the Value of determines the degree of acoustic anisotropy induced by uniaxial stress.

If the initial state is characterized by the absence of any loads applied to a manageable amount of material that can be considered characteristic of the material, namely, by setting his own acoustic anisotropy associated mainly with the manufacturing technology. The parameter is associated with the elastoplastic structural (textural) and possibly other physico-mechanical characteristics. For example, materials manufactured by stamping, almost acoustically isotropic for waves propagating in the direction along which the carried out punching. For sheet metal value is usually positive, if the direction 1 select the direction of hire, and may reach several percent.

9.4 In the case when , differ significantly (by more than 1.5% -2%), biaxial NS calculated by the formulas:

; (12)

, (13)

where , the coefficients provocations regard to stresses acting along and across the direction of rolling, respectively:

; (14)

; (15)

. (16)

Note — Coefficients , , calculated on the basis of known or experimentally measured , , , . Factor correction, its value is several times less , so its dependence on the direction of load application may be disregarded (that should take the average to directions along and across the direction of rolling).

9.5 Uniaxial tension for this material is calculated by the formula:

(17)

either

, (18)

where , the coefficients provocations regard to uniaxial tension acting along and across the direction of rolling, respectively, which are calculated on the basis of known or experimentally measured , , , :

; (19)

. (20)

9.6 When the temperature of the material at 10 °C and more in the formulas (3), (4), (12), (13) replace on where is the thermoacoustic coefficient based on the difference of the temperature coefficients of the propagation time of the longitudinal and shear waves in the material, and the difference of its temperature when carrying out acoustic measurements in the loaded and unloaded States.

10 the Rules of registration of testing results

10.1 the results of the control record in the journal, the form of which is given in Appendix A.

Additional information to be logged, the order of registration and storage of the journal (or conclusion) should be set in the technical documents for the control.

10.2 If stress measurements are part of the research work, the results of the measurements should be made in accordance with the General requirements and rules of registration of reports on research work.

10.3 the results of the survey should be maintained until the next control OK.

Application (recommended). Form of the journal of determination of mechanical stresses in the material OK acoustic method

Appendix A
(recommended)

The electronic text of the document
prepared by JSC «Code» and checked by:
the official publication of the
M.: STANDARTINFORM, 2007