# The way to determine the quality products from a reliable and probabilistic parts of the residual defects

The invention relates to the field of non-destructive control of discontinuities, irregularities and other defects of material product or group of products. The way to determine the critical size of defects in the operation mode, valid in operation the size of defects and acceptable manufacturer defects dimensions. The testing results are in the form of a histogram. Determine the probability of defect detection, the original defect and residual defects. The residual defect is defined as the difference between the original and the detected defects. Residual defects are divided into a reliable part and probabilistic. The resulting size of the defects is compared with the critical flaw size with a maximum in operation the size of the defect and valid in manufacturing flaw size. By comparing the results conclude on the quality of the product and its operation. The invention allows to evaluate the real defects of the product after inspection and repair identified defects and to establish the boundary between the sizes of the defects. 10 C.p. f-crystals, 5 Il.

The invention relates to the field of nondestructive testing (on the clients designs and so on), including ultrasonic, eddy current, radiography and other NDT methods. The invention can be applied when evaluating the quality, reliability and safety of the product according to the NDT results, assessing the suitability of NDT methods and the adequacy of the level of qualification of the operators NK, control of products during use and/or manufacture.

There is also known a method of determining the defectiveness of the product (GOST 14782-86), which make the standard sample with small defect size obtained by drilling or milling, which adjusts the sensitivity of determining the validity of this method of control (and control). It is believed that the higher the sensitivity, the higher the reliability of the TC, but the quantitative characteristics of this relationship in the specified method is not set, i.e. the method does not permit the assessment of real defects after repair of detected defects.

In accordance with the existing practice in modern technology NC is responsible products after manufacture, before commissioning and during operation. It is assumed that the NC identifies all defects that are available for detection by this method the sizes, classified as defects and will be repaired by the repair. Believe that after NC and repair identified defects other defects in the product (see, for example, the Equipment and pipelines of nuclear power installations. Welded joints and welding. Control rules, PNEG-7-010-89, Gosatomnadzor, Energoatomizdat, 1991). The same practice has developed and abroad. Thus, it is believed that the original (to NC) in the product were the defects that were detected in the control process, and after inspection and repair identified defects in the product left.

The disadvantage of this approach is that when evaluating as a source of defects in the product, and residual defects (i.e. defects remaining in the product after its inspection and repair of detected defects) do not take into account the real possibility of missing the defects used methods of control operators NC with a certain level of qualification. It is known (for example, Gurvich, A. K. Reliability of flaw detection control as the reliability of the system “Flaw - operator - environment, Inspection, 1992, No. 3, S. 5-13) that in almost all cases, NC there is a significant probability of missing a defect of the big sizes in excess of the allowable resluts defects. These defects ultimately determine the reliability and performance of the product.

The technical result, which directed this invention is that it allows assessment of the real defects of the product after inspection and repair identified defects and to establish the boundary between the sizes of defects that validly exist in the product (the probability of their existence is equal to 1), and size of defects, which may or may not be in the product (the probability of their existence is less than 1). Knowledge of the size of defects, validly existing product (after inspection and repair of detected defects) and will more accurately assess the actual condition of the product, the possibility of reliable and safe operation, the acceptability of certain methods of NDT, quality technology manufacturing products, as well as, if necessary, to take reasonable steps to improve the quality and reliability of the product to an acceptable level.

The technical result is achieved in that in the method of determining the quality of the product, including the identification of defects in products using non-destructive testing, determine the critical dimensions of the_{kr}defects and acceptable in the manufacture of dimensions []_{technology}defects

the testing results are in the form of a histogram in the coordinates (N_{OBN},), where N_{OBN}- the number of detected during the inspection of defectsthe characteristic size of the defect, determine the probability of defect detection P_{water}determine the original defect N_{Ref}=f() evaluate the residual defect N_{OST}=() as the difference of N_{Ref}and N_{OBN}residual defects razreshayut on reliable part_{d}and probabilistic part>_{d}where-the characteristic defect size_{d}- the size of the defects at the boundary between true and probabilistic parts defined:

where_{max}- maximum size of defects in this product;

_{d}compare withGenerally, as the characteristic dimensiondefect is selected linear dimension of the defect, or a combination of the linear dimensions of the defect, or the defect area, or volume of the defect.

In one embodiment, approximate historama (N_{OBN,}_{}) by the equation

N_{OBN}()=And^{-n}{1-(1-)exp[-(-_{0})]-}, (2)

where A, n,,- constant, which is determined from the condition of the best approximation for N_{OBN}(to the monitoring results, presented in the form of a histogram,

_{0}- minimum available for the detection of the defect size

the original defect N_{Ref}determined by the formula:

N_{Ref}=And^{-n}, (3)

and the probability of defect detection P_{water}according to the formula:

In the particular case as har who have a defect, the ratio a/C take constant for all a, determined from the condition of maximum speed the development of the defect in service.

When this_{kr}[]_{D. E.}and []_{technology}determine for a specific product or group m of the same products, with the control m the same products all inspection results are summed and represented as a single histogram.

In this case the residual defectin the field of defects, important to safety, defined as the number of defects in the product, the dimensions of which are equal to or greater than the critical size []_{kr}mode of operation:

residual defectsin the area of defects is important for reliability, defined as the number of defects that are larger than the sizes of the defects []_{D. E.}limit of use of the product:

residual defectsin the field �img.russianpatents.com/chr/967.gif" border="0">]_{technology}valid in the manufacture of discontinuities:

where_{before}- the maximum possible characteristic defect size

m is the number of the same products.

While the lowest available for the detection of defect size_{0}determine if the flaw detector setup used in the control of the product, or as the minimum size of defect that was detected during the inspection.

To simplify the calculations, constantis equal to 0.

In another embodiment, produce a test sample, designed to determine characteristics of non-destructive testing of discontinuities in the material, control of this test sample by the method of non-destructive testing and monitoring of the product, which is produced by the same method as the control test sample, the test sample is made in the form of a product or the most critical part of the same material and on the same technology as the product are located randomly defects with different characteristic sizesdetermine the probability of detecting the_{OBN}()/N_{hall then}(), (8)

where n_{OBN}the number of detected during testing of the test specimen defects,

N_{hall then}the number laid in the manufacture of the test specimen defects, the original defect is defined as;

N_{Ref}=N_{OBN ed}/P_{water}() (9)

the histogram (N_{Ref},) are approximated by the equation N_{Ref}=f(or N_{Ref}=f(a,c), where a,is the linear size of defects, and when determining residual defects in N_{OST}the value of N_{OBN ed}determine from the analytical expressions of N_{OBN ed}=N_{Ref}·_{}P_{water}().

When the test sample contains three groups of defects: defects, dimensions which lie in the interval from defects dimensions, permissible during operation, to the size of the critical items in the operation mode; defects whose sizes lie in the range from sizes that are valid in the manufacture of products, up to defect size, valid for operation; defects whose sizes lie in the range from the minimum size available to identify getexplanation nature, and the third type of process, residual defectsin the field of defects, important to safety, defined as the number of defects in the product, the dimensions of which are equal to or greater than the critical size_{kr}mode of operation:

residual defectsin the area of defects is important for reliability, defined as the number of defects that are larger than the defect size_{doctor of Economics,}limit of use of the product:

residual defectsin the field of defects in determining the quality of production, as the number of defects that are larger than the dimensions of the_{technology}valid in the manufacture of discontinuities:

where_{before}- maximum characteristic size of the defect.

The histogram (N_{Ref},) are approximated by the equation type

N_{Ref}=And_{x}UOM N_{Ref}=And_{a,C}exp[-n_{a,C,}(a^{2}/(C)], or N_{Ref}=And_{F}exp(-nF), or N_{Ref}=And^{-nx}or N_{Ref}=And_{and}or N_{Ref}=And_{a,C}(a^{2}/or

where a, is the linear size of the defect,

F - area defect

n, And the coefficients are chosen from the condition of maximum approach of the analytical curve to the experimental data.

In Fig.1 shows a schematization of the defect in the pipe by an ellipse with semi-axes a and C of Fig.2 shows the set of defects of critical size is valid in operation sizes and allowable sizes of discontinuities in the manufacture of (relevant standards for manufacturing are shown in table NTD, PNEG-7 010-89)), Fig.3 - characteristics of reliability of the TC in the form of the dependence of the probability of detection of defects P_{water}from their size and, in Fig.4 - histogram of the identified product defects, Fig.5 is a graph of residual defects.

The method can be used for a specific product or group of similar products, quality workmanship, reliability and security Coty qualification.

Methods of fracture mechanics to determine the critical defect size in the mode of operation for this product_{kr}maximum allowable operation defects []_{D. E.}acceptable manufacturer defects dimensions []_{technology}(the norm of the defect), as defined by applicable regulations and/or specifications for the manufacture (the characteristic size of the defect, for example, is selected linear dimension of the defect, or a combination of the linear dimensions of the defect, or the defect area, or volume of the defect). It should be noted that the defects that define the quality is defects whose sizes are in the range from the minimum available for defect detection (search) to the size of defects that are valid in the manufacture and above; defects, determine reliability, is defects whose sizes are in the range from acceptance at the manufacturer to an acceptable during the operation above, the defects that determine the security is valid from when the operation of the critical dimensions and higher.

The set of defects of critical size (curve 3), valid in exp is a of Fig.2.

Conduct non-destructive testing products (NDT) method (ultrasonic, eddy current, radiography and other NDT methods and technical means of control operators specific skills.

The testing results are in the form of a histogram in the coordinates of the characteristic defect sizethe number of detected defects of a given size N_{OBN ed}”.

Next, determine the probability of defect detection P_{water}the original defect N_{Ref}=f(and residual defects N_{OST}=() as the difference of N_{Ref}and N_{OBN}.

These dependencies can be determined by various methods.

According to one variant of the NDT results are in the form of analytical expressions.

The structure of the equation, which can describe the results of the TC represented by the histogram, the following:

N_{OBN}()=N_{Ref}()P_{water}() (14)

where N_{Ref}- the number of detected during the inspection of defects per unit of characteristic size. If the dimension N_{OBN}mm^{-1};

N_{Ref}function source (to NC) defects with the same dimension, and N_{OBN};

P_{water}- the probability of detecting a defect of a given size.

The appearance of features N_{Ref}and R_{water}determined based on the condition of maximum simplicity of expression, the minimum number of constants and compliance physically due to dependency N_{Ref}and R_{water}. In the first approximation can be used the following equations:

N_{Ref}=And^{-n}, (14)

N_{OBN}()=And^{-n}{1-(1-)exp[-(-_{0})]-}, (16)

where A, n,,,_{0}- constant.

Determine the numerical values of the constants A, n,,from the condition of maximum approximation equations N_{OBN}(in the first approximation can be taken equal to 0. The result is a three unknowns, which greatly facilitates the task of their definition.

To determine the constant A, nyou can either solving the system of three equations for A, n andwho receive, if we take three points on the histogram, or define them using the method of least squares.

Residual defects N_{OST}defined as the difference of N_{Ref}and N_{OBN}:

N_{OST}()=N_{Ref}()-N_{OBN}(). (17)

While the number of remaining defects in the product is determined in three ranges: residual defectsin the field of defects, important to safety, defined as the number of defects in the product, the dimensions of which are equal to or greater than the critical size_{kr}mode 7232.gif" border="0">in the area of defects is important for reliability, defined as the number of defects that are larger than the sizes of the defects []_{doctor of Economics,}limit of use of the product:

residual defectsin the field of defects in determining the quality of production, as the number of defects that are larger than the dimensions []_{technology}valid in the manufacture of discontinuities:

where_{before}- maximum characteristic size of the defect in this design with given geometry (e.g., in the direction of thickness of the vessel wall pressure limiting defect size is equal to the wall thickness),

m is the number of the same products.

For the histogram, the horizontal axismust include a critical size defect, even if the control of all identified defects have not reached a critical size.

In the case of control a few of the same products all inspection results are summed and represented as a single histogram. Than >what according to another variant to determine the dependencies of P_{water}(the probability of defect detection), N_{Ref}=f() (original defect) and N_{OST}=() (ostateczny deficiency) make a test sample.

Taking into account the real operating loads and conditions determined for the product (e.g., pipeline, Fig.1) methods of fracture mechanics (including safety factors) defects (discontinuities):

The set of defects of critical size (curve 3), valid in operation dimensions (curve 2), and the allowable size of the discontinuities in the manufacture of curve (1) shown in Fig.2

The test sample is made on the shape of the product and the scale of about 1:1 to the product or its most critical part. The most critical part of the product is that part of the product, in which the most likely defects (welds, designated maximum operational impacts, etc.,) or the destruction of which is the danger. A test specimen made of the same material and on the same technology as the product. In the test samples lay artificial defects of three types:

- dicecca for products in production mode

- defects whose sizes lie in the range from sizes that are valid in the manufacture, up to defect size, permissible during operation,

- defects whose sizes lie in the range from the minimum available for defect detection to defect size, valid in the manufacture (in this case, it is permissible for the upper boundary of the interval exceeded the size of defects that are valid when the manufacturer).

While the first two types of defects (discontinuities) should mimic the defects of an operational nature, and the third type - technological Operational defects - defects that can arise from manufacturing defects or to germinate and grow under operating loads (fatigue cracks, cracked corrosion stress cracking, etc), technological defects are defects, the occurrence of which is connected with the peculiarities of the technology of manufacture or Assembly (incomplete penetration, incomplete fusion, pores, etc). It is possible to bookmark the various combinations of types of defects (one, any two, three), if necessary, may also manufacture different numbers of samples, each of which will be laid one type of defects or their various combinations.

It should also be noted that the defects include in the sample randomly, for example, using tables of random numbers.

The minimum allowable distance between the defects is determined proceeding from the conditions of existence of single defects (if laid a single defects) or less for a group of cracks in terms of mutual influence is known, for example Methodical recommendations Mr 108.7-86, M: TSNIITMASH, 1986).

The number of defects of each type should be sufficient for statistical analysis of the results, for example not less than 9pcs. (Fewer results less reliable).

Any defect can be modeled conservatively crack, and any crack can be described by an ellipse with semi-axes: short and long S.

There are various options bookmark defects in the test sample.

In the test sample lay defects in the form of ellipses, and the ratio of the axes of the ellipse accept on the basis of the maximum velocity defect growth in operational stress field;

In the test sample lay defects in the form of ellipses, the ratio oreokastro defect or the projected area of the voluminous defect on the plane of the probable development of the defect;

In the test sample lay defects in the form of ellipses, with the number of defects and the ratio of the axes of the ellipse is chosen using the mathematical methods of experiment planning, based on the condition of minimizing the number of laying defects (K. Daniel, Application of statistics to industrial experimentation. M.: Mir, 1979);

If put to the test sample defects not have the shape of an ellipse, they schematize ellipses.

After fabrication of the test sample to produce a control using the same tools and methods for monitoring and operators of the same qualification, which will then be used to control the product, the inspection results are compared with real defects inherent in the test sample.

For each characteristic dimension of the defect is determined reliability as a function of defect detection probability P_{water}():

P_{water}()=N_{OBN}()/N_{hall then}(), (8)

where N_{OBN}the number of detected during testing of the test specimen defects,

N_{hall then}the number laid in the manufacture of the test specimen defects,

P_{water}=1-(1-)exp[-_{NK}(a-a_{0})(C-C_{0})]-or (18)

P_{water}=1-(1-)exp[-_{NK}(-_{0})]-(20)

where_{NK}the confidence factor NC, characterizes the increase in the detection of defects depending on its size;

- constant characterizing the limit of detectability of control by this method with arbitrarily large size of the defect; if the detail sizes small, then this value can be neglected by typing the appropriate adjustment of the value of_{NK}.

the characteristic defect size, n is the same;

and_{about}c_{about}- the minimum size of defects that are available for the detection of NK.

Then hold control of the product and the testing results are in the form of a histogram in the coordinates of the characteristic defect sizethe number of detected defects of a given size N_{OBN ed}”.

The original defect N_{Ref}determine the ratio of N_{OBN ed}/P_{water}(); the resulting histogram is approximated by the equation N-type_{Ref}=Andexp(-n), ororor

or

oror

where a, is the linear size of the defect,_{c}the distribution function of magnitude, for example the normal distribution law,

F - area defect

n, A, D,the coefficients are chosen from the condition of maximum approach of the analytical curve to the experimental data the practical size you can take a small semi-axis a of the ellipse, which schematize the defect, the ratio a/C take constant for all and, on the basis of the maximum velocity defect growth in operating conditions;

for example, in the case of the normal distribution, uniform stress field and/C=2, D=a/2, we obtain

Residual defects get as the difference between the N_{Ref}and N_{OBN ed.}In this case N_{OBN ed}determine from the analytical expressions of N_{Ref}·_{}P_{water}(), i.e. the residual defect N_{OST}can be represented in the form of the equation

Residualin the field of defects, important to safety, defined as the number of defects in the product, the dimensions of which are equal to or greater than the critical size_{kr}mode of operation:

residual defectsin the area of defects is important for reliability, defined as the number of defects that are larger than the defect size~~in the field of defects in determining the quality of production, as the number of defects that are larger than the dimensions of the~~_{technology}valid in the manufacture of discontinuities:

~~where~~_{before}- maximum characteristic size of the defect.

~~Next, the residual defects are divided into a reliable part~~_{d}in^{}which defects with sizes_{d}there are authentic, and a probabilistic part>_{d}in which defects with sizes>_{d}may or may not be.

~~The boundary between true and probabilistic parts of residual defects is determined from the conditions:~~

~~where~~_{max}- maximum size of defects in this product.

_{]technology,and by comparing the results draw conclusions about the quality, reliability and safety of the product.}

~~The invention is illustrated by the following example.~~

~~It is necessary to ensure the quality of the two pipes of internal diameter D=800 mm wall thickness S=34 mm from pearlitic steel. Critical size defects in girth welds is shown in Fig.2 (curve 1). Valid in operation defects determined using the equations of fracture mechanics and factors of safety (curve 2 in Fig.2). Norms of defects in the operation shown in Fig.2 curve 3.~~

~~In the NC standard method and means prior to the operation (after installation) was detected 47 of discontinuities.~~

~~All identified discontinuities (defects) are presented as histograms in Fig.3.~~

~~At the same time as the characteristic dimension of the defect selected width of the defect in the direction of the thickness of the wall - or rather, the semiminor axis of the ellipse, which was shemaleshemale all identified defects.~~

~~When the ratio a/0,5 critical size defect corresponds to=15 mm []~~_{D. E.}=6 mm, []_{and what if" border="0">max=13 mm, the x-axis contains the critical size=15 mm}

~~The equation describing the number of detected defects N~~_{OBN}depending on the size and:

~~Control minimum detected defect had a=0.6 mm~~

~~To determine the constant A, nsolve system of three equations with respect to these constant:~~

~~the 1st equation to get the point with coordinates (a=1 mm, N~~_{OBN}=20) Fig.3:

~~20=A· 1~~^{-n}[1-exp[-(1-0,6)]]; (26)

~~2nd equation to get the point with coordinates (a=5 mm, n~~_{OBN}=4) Fig.3:

~~4=As· 5~~^{-n}[1-exp[-(5-0,6)]]; (27)

~~the 3rd equation to get the point with coordinates (a=13 mm, n~~_{OBN}=0,66 in Fig.3:

~~0,66=A· 13~~^{-n}[1-exp[-(13-0,6)]]. (28)

~~For the 3rd equation of n~~_{OBN}=0,66 obtained as the averaged number of detected defects in the interval from 11 to 13 mm, which accounted for 2/3, where 2 is the number of detected defects, 3 - the number of intervals.

~~Finally, the system of equations has the form:~~

~~20=A· [1-exp(-0,4)]~~

~~4=A· 5~~^{-n}[1-exp(-4,4the, ngave the following results:

~~A=1000 mm, n=2,56,=0,05 mm~~^{-1}

~~Substituting the constants a, n,in the corresponding equations, get: equation source defects:~~

~~N~~_{Ref}=1000A^{-2,56}; (30)

~~the equation of the probability of defect detection:~~

~~P~~_{water}=1-exp[-0,05(a-0,6)]; (31)

~~equation residual defects~~

~~N~~_{OST}()=N_{Ref}()-N_{OBN}(). (17)

~~The equations presented in Fig.4.~~

~~Solve the equation~~

~~relatively~~_{d}. When this_{max}=S, where S is the thickness of the pipe wall. The results shown in Fig.5 as curve 2.

~~The thus determined value and~~_{d}=14 mm

~~For given operating conditions, the most rapid growth in the area of the defect will be provided at a/with0,5. Critical defect size will be set as~~_{kr}=15.5 mm, which is close to the value of a_{d}=14 mm, Considering that the operation of the defect with a_{d}

~~Claims~~

~~1. The way to determine the quality of the product, including the identification of defects in products NDT method, characterized in that to determine the critical dimensions of the~~_{kr}defects in the operation mode, valid in operation dimensions []_{D. E.}defects and acceptable in the manufacture of dimensions []_{technology}defects, the inspection results are in the form of a histogram in the coordinates (N_{OBN},), where N_{OBN}- the number of detected during the inspection of defectsthe characteristic size of the defect, determine the probability of defect detection P_{water}determine the original defect N_{Ref}=f() evaluate the residual defect N_{OST}=() as the difference of N_{Ref}and N_{OBN}residual defects are divided into a reliable part>_{d}where- the characteristic defect size_{d}- the size of the defects at the boundary between true and probabilistic parts defined from

~~where~~_{max}- maximum size of defects in this product;

_{d}compare with_{kr}, []_{D. E.}and []_{technology}and by comparing the results conclude about the quality of products and the possibility of its operation.

~~2. The method according to p. 1, characterized in that as the characteristic dimensiondefect is selected linear dimension of the defect, or a combination of the linear dimensions of the defect, or the defect area, or volume of the defect.~~

~~3. The method according to p. 1 or 2, characterized in that approximate the histogram (N~~_{OBN},) by the equation

~~N~~_{OBN}()=And^{-n}{1-(1-)exp[-

_{OBN}(to the monitoring results, presented in the form of a histogram,

_{0}- minimum available for the detection of the defect size

the original defect N_{Ref}determined by the formula:

N_{Ref}=And^{-n},

and the probability of defect detection P_{water}according to the formula:

P_{water}=1-(1-)exp[-(-_{0})]-.

4. The method according to p. 2 or 3, characterized in that as the characteristic dimension take minor axis and the ellipse, which schematize the defect, the ratio a/C take constant for all a, determined from the condition of maximum speed the development of the defect in service.

5. The method according to any of paragraphs.1-4, characterized in that_{kr}, []_{D. E.}and []_{technology}OPE inspection results summarize and present in a single histogram.

6. The method according to p. 5, characterized in that N_{OST}define three ranges: residual defectsin the field of defects, important to safety, defined as the number of defects in the product, the dimensions of which are equal to or greater than the critical size_{kr}mode of operation:

residual defectsin the area of defects is important for reliability, defined as the number of defects that are larger than the sizes of the defects []_{D. E.}maximum permissible product use:

residual defectsin the field of defects in determining the quality of production, as the number of defects that are larger than the dimensions []_{technology}valid in the manufacture of discontinuities:

where_{before.}- the maximum possible characteristic defect size

m is the number of the same products.

7. The method according to any of paragraphs.3-6, distinguishing the t when configuring the detector, used to control the product, or as the minimum size of defect that was detected during the inspection.

8. The method according to any of paragraphs.3-7, characterized in that the constantis equal to 0.

9. The method according to p. 1 or 2, characterized in that the manufactured test pattern designed to determine characteristics of non-destructive testing of discontinuities in the material, control of this test sample by the method of non-destructive testing and monitoring of the product, which is produced by the same method as the control test sample, the test sample is made in the form of a product or the most critical part of the same material and on the same technology as the product located randomly defects with different characteristic sizesdetermine the probability of detection of defects P_{water}():

P_{water}()=N_{OBN. then}()/N_{hall then}(),

where N_{OBN. then}the number of detected during testing of the test sample defects;

N_{hall. then}- the number set by the manufacturer �D/chr/967.gif" border="0">),

the histogram (N_{Ref},) are approximated by the equation N_{Ref}=f(or N_{Ref}=f(a, C), where a, is the linear size of defects, and when determining residual defects in N_{OST}the value of N_{OBN. ed}determine from analytical expressions

N_{OBN. ed}=N_{Ref}·_{}P_{water}().

10. The method according to p. 9, characterized in that the test sample contains three groups of defects: defects, dimensions which lie in the interval from defects dimensions, permissible during operation, to the size of the critical items in the operation mode; defects whose sizes lie in the range from sizes acceptable in the manufacture of a product to the size of defects that are valid for operation; defects whose sizes lie in the range from the minimum size available for the detection of flaws, defects, valid in the manufacture of the first two types of defects simulate operational defects of nature, and the third type of process, residual defectsin the field of defects, important to safety, defined as the number of defects in the product, the size of the AI articles:

residual defectsin the area of defects is important for reliability, defined as the number of defects that are larger than the defect size_{D. E.}maximum permissible product use:

residual defectsin the field of defects in determining the quality of production, as the number of defects that are larger than the dimensions of the_{technology}valid in the manufacture of discontinuities:

where_{before.}- maximum characteristic size of the defect.

11. The method according to p. 9 or 10, characterized in that the histogram (N_{Ref},) are approximated by the equation type

N_{Ref}=And_{x}exp(-n_{x}),

or N_{Ref}=And_{and}exp (-n_{and}a)

or N_{Ref}=And_{a,C}exp[-n_{a,C,}(a^{2}/s)],

or N_{Ref}=And_{F}exp(-nF),

or

or N_{Ref}=And_{and}F - defect area;

n, And the coefficients are chosen from the condition of maximum approach of the analytical curve to the experimental data.

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FIELD: automatic control, applicable in systems with excessive quality of transducers, for example, accelerometers, a failure of one of which should not result in a failure of the control system.

SUBSTANCE: the method is based on a periodic check-up of relation between the measured parameters of motion characterizing the correct operation of the transducers, fixation of the moment of failure of the relation, comparison of the readings of the transducers at this moment and at the moment preceding the moment of disturbance of the relation, and determination of the failed transducer by the results of the comparison.

EFFECT: expanded functional potentialities due to possibility of determination of the failed transducer in any excess system.

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