RU2666158C2 - Method for non-destructive testing of product quality - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: surface of the monitored object is scanned with sensors of physical fields, signal values from each surface point of the monitored object are measured, range of signal values is divided by their values into I intervals, the measured signals are recorded according to their belonging to corresponding intervals, a number of measured signals in each interval is determined, difference of the number of measured signals is calculated in the subsequent and previous intervals over the entire range of values of the measured signals, as a threshold value of the radiation signal value of the physical field a value is selected from the interval for which the difference of the number of measured signals in this and the previous intervals is less than zero, and the difference of the number of measured signals in this and subsequent intervals is more than zero. It is assumed that the signal in the defective area is less than the signal in the qualitative area in quantity, the probability of false defect detection and the probability of defect skip, based on monitoring tasks. The signal quantity is measured at the center of the interval, which receives the greatest number of signals from the defective area. The signal quantity is measured at the center of the interval, which receives the greatest number of signals from the qualitative area. The number of the interval m corresponding to a value of 0.67 U^d _max, and the number of the interval n corresponding to 0.67 U^Q _max are measured. In addition, the signal is measured at the center of the interval m and at the center of the interval n. The root-mean-square value of the signal distribution in defective areas is determined. The root-mean-square value of the signal distribution in qualitative areas is determined. The ratio between the probability values of false defect detection and defect skip is set P^d _fal. and P^d _sk.. The numerical value of the threshold signal is determined by solving the reduced equation.

EFFECT: providing an opportunity to increase the reliability of defect detection and to ensure the defect detection with a given probability.

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Description

Technical field

The invention relates to the field of measuring equipment and can be used to assess the reliability and quality of various products. The use of this product for the control of materials with a wide variation in characteristics (defined as the result of exposure to various physical fields with the controlled material - thermal, acoustic, radio waves, etc.), for example, multilayer structures made of polymer composite materials (PCM), is especially relevant.

The invention can be used to control the reliability and quality of complex spatial multilayer PCM structures both during production and during operation: spatial mesh structures, spacecraft compartments, rocket engines, aircraft engine elements, pipelines, pressurized vessels, etc.

Particularly effective is the application of the claimed invention in testing potentially dangerous and expensive to manufacture structures, which, on the one hand, have high requirements for reliability and quality of operation, and on the other hand they are quite expensive and time-consuming to manufacture so that a sufficiently large number of structures can was replaced by other products having the required parameters. Reliable defect identification is very relevant for rocket and space technology products where there are mutually exclusive requirements: when, on the one hand, it is necessary to ensure the necessary reliability of the structure (i.e., for example, to increase the thickness of the structure), and on the other hand, there are restrictions on weight and overall dimensions that require reducing the thickness of the materials. In this case, it is necessary to identify potentially dangerous places (structural units), which in the first place can be destroyed (due to the presence of defects such as discontinuity), which can lead to an accident and which may need to be strengthened.

State of the art

A reliable determination of the quality of material continuity is an urgent task in the process of creating effective and reliable structures from various materials.

There are a fairly large number of methods for controlling the continuity of the material: the X-ray method, the ultrasonic method, the visual optical method, and the eddy current method.

All methods have their own characteristics and applications. But all methods have one common operation - the process of detecting discontinuities (defects), i.e. the allocation in the controlled material of areas having characteristics different from the main material. This can be, for example, cracks, delaminations, etc. The task is greatly complicated by the presence of a complex surface shape of the product and a complex internal structure - for example, turbine blades.

A promising direction in modern technology is the use of composite materials, both metallic and polymeric, which have a number of advantages over traditional materials, especially in the aerospace industries, engineering, energy, etc. This is caused by a wide variety of types of such materials, specific design features of them and manufacturing technology, and a random change in physico-mechanical and strength characteristics, a wide variety of types of materials, and their characteristics uk.

In addition, these materials in most industries operate under static and dynamic loads.

Improving the quality of structures is impossible without a reliable assessment of the quality criteria of materials. Accordingly, it is impossible to develop measures and technologies to improve the quality of structures. One of the signs of the quality of structures, especially in the aerospace and aerospace industries, is the weight and size and energy characteristics, which are determined, including quality of material continuity

Given that such structures are, as a rule, quite expensive, both in cost terms and in the laboriousness of manufacturing, and it is obvious that the failure of their structure leads to large financial and other losses, it is necessary, on the one hand, to test each structure for testing the conformity of its quality characteristics to the required, and on the other hand, these tests should minimize “injure” the structure with maximum information content of the test results.

Here, non-destructive testing methods based on various physical principles and methods reliable for the solved problem of detecting internal discontinuities by analyzing changes in the results of the interaction of physical fields with the controlled material come first. They allow you to objectively determine the actual state of the structure, evaluate the reliability of their operation and give recommendations for its repair or restoration.

There are a large number of methods and means for detecting discontinuities in the process of non-destructive testing of materials (flaw detection).

Analogs of the invention - methods for detecting defects in the process of non-destructive testing - are described in detail in the following materials:

1. I.N. Ermolov, N.P. Aleshin, A.I. Potapov. Unbrakable control. Acoustic control methods. Prince 2. - M .: High School 1991, p. 92-95.

2. EP 0486689 A1, 05.27.1992.

3. SU 1396046 A1, 05/15/1988.

4. SU 1158919 A, 05/30/1985.

5. SU 319895, 02/02/1971.

6. SU 1649414 A1, 05/15/1991.

7. SU 824032, 04/23/1981.

8. DE 4031895 A1, 04/25/1991.

A common drawback of almost all existing non-destructive testing methods and means is as follows: the threshold value of the signal is determined by means of a reference sample with a reference defect. Defective areas are detected by comparing the signal across the surface of the material being monitored with the threshold value of the signal. This is a simple and reliable method. However, it has a fundamental drawback: it is practically impossible to produce reference samples with all variants of the characteristics of internal defects, which means that as a result some “averaged” defect is detected and it is very likely that dangerous defects can be missed. This method does not take into account the effect of random changes in the properties of controlled materials on the results of control.

Therefore, today there is a need to create a method for monitoring real structures from complex materials, which can be applied in practice for a wide range of objects with different characteristics and can detect various types of internal defects.

The present invention is directed to solving the problem of providing reliable reliable quality control of the continuity of multilayer complex structures and their elements in the production process and in actual use. Those. ultimately, the invention is aimed at improving the safety of operation of complex potentially hazardous structures.

The closest analogue to the claimed is a method of non-destructive quality control of an object described in patent No. 2171469.

This method is aimed at determining the threshold value of the signal in the process of non-destructive testing and includes the following actions:

- scan the surface of the controlled object with information sensors of physical fields,

- measure the magnitude of the signals of the radiation of the physical field from each point on the surface of the controlled object,

- break down the entire range of values of the signals of the radiation of the physical field according to their values at I intervals,

register the measured signals by belonging to the corresponding intervals,

- determine the number of measured signals in each interval (K _i ),

- calculate the difference in the number of measured signals in the subsequent and previous intervals (ΔK _i = K _{i + 1} -K _i ) over the entire range of values of the measured signals,

- and as a threshold value of the value of the radiation signal of the physical field, choose a value from the interval for which the difference in the number of measured signals in this and previous intervals is less than zero, and the difference in the number of measured signals in this and subsequent intervals is greater than zero.

This method is more reliable than the methods given as analogues, but has a significant drawback. In the process of solving the practical problems of non-destructive testing of critical products, it is often necessary to set such a threshold value of the signal that would allow to detect all defects (discontinuities) with a probability more than specified, while allowing for rejection. Those. the task is to prevent the product with defects from working. The known method does not allow this.

SUMMARY OF THE INVENTION

The technical result achieved by using the invention is to increase the reliability of detecting defects and to ensure the identification of defects with a given probability, i.e., ultimately, increasing the reliability of the results of assessing the technical and operational status of complex structures and their elements.

The technical result is achieved due to the fact that in the known method, after calculating the difference in the number of measured signals in the subsequent and previous intervals over the entire range of values of the measured signals, the following actions are performed:

- a priori determine that the larger is the signal in the defective section or the signal in the high-quality section, it is accepted for definiteness that the signal in the defective section is smaller in magnitude of the signal in the high-quality section,

и

, здесь- ask

and

, here

- вероятность ложного обнаружения дефектов,

- the probability of false detection of defects,

- вероятность пропуска дефектов,

- probability of missing defects,

these values are determined by the control requirements: what takes precedence is the detection of all defects with a probable rejection or the absence of a rejection with a certain probability of missing defects,

, удовлетворяющего следующим условиям:- measure the magnitude of the signal in the center of the interval, which falls the largest number of signals of the defective area -

satisfying the following conditions:

, удовлетворяющего следующим условиям:- measure the magnitude of the signal in the center of the interval, which falls the largest number of signals of the high-quality section -

satisfying the following conditions:

where i is the number of the measurement interval,

и номер интервала (n), соответствующего 0,63

,- determine the number of the interval (m) corresponding to a value of 0.67

and the interval number (n) corresponding to 0.63

,

- determine the rms value of the distribution of signals in defective areas:

- determine the rms value of the distribution of signals in high-quality areas:

и

- set the ratio between the values:

and

, при этом

, wherein

the χ value is determined on the basis of the tasks facing the control: either to identify all defects, but at the same time re-processing is allowed, i.e. false detection of defects, or detect only obvious defects, but at the same time partial skipping of defects is allowed, and

путем решения уравнения следующим образом:- determine the numerical value of the threshold signal

by solving the equation as follows:

Description of the figures of the drawings

The invention and the possibility of achieving a technical result will be more clear from the following description with reference to the position of the drawings, where:

FIG. 1 shows a model histogram of the distribution of signals,

FIG. 2 shows the actual initial distribution of signals on the surface during automated control in the form of color gradation,

FIG. 3 shows a histogram of the real distribution,

FIG. 4 shows a defectogram after signal processing according to the method described in the prototype,

FIG. 5 shows a defectogram after signal processing according to the claimed method.

The following notation is used in the figures:

- величина сигнала в центре интервала, на который попадает наибольшее количество сигналов дефектного участка,

- the value of the signal in the center of the interval, which falls the largest number of signals of the defective area,

- величина сигнала в центре интервала, на который попадает наибольшее количество сигналов качественного участка,

- the magnitude of the signal in the center of the interval, which falls the largest number of signals of the high-quality section,

i is the number of the measurement interval,

- величина сигнала в центре интервала, который соответствует 0,67

,

- the value of the signal in the center of the interval, which corresponds to 0.67

,

- величина сигнала в центре интервала, который соответствует 0,67

,

- the value of the signal in the center of the interval, which corresponds to 0.67

,

- среднеквадратичное значение распределения сигналов на дефектных участках,

- the rms value of the distribution of signals in defective areas,

- среднеквадратичное значение распределения сигналов на качественных участках,

- the rms value of the distribution of signals in high-quality areas,

Preferred Embodiment

All electronic components used are built on the basis of standard microprocessor circuits and microprocessor assemblies with reprogrammable memory devices (see, for example, Ugryumov EP Digital circuitry: textbook for universities. - 3rd ed. Revised and supplement. - St. Petersburg .: - BHV-Petersburg, 2010).

The method is as follows.

Scan the surface of the controlled object with information sensors of physical fields,

measure the magnitude of the radiation signals of the physical field from each point on the surface of the controlled object,

break down the entire range of values of the signals of the radiation of the physical field according to their values at I intervals,

register the measured signals by belonging to the corresponding intervals,

determine the number of measured signals in each interval K _i ,

calculate the difference in the number of measured signals in the subsequent and previous intervals ΔK _i = K _{i + 1} -K _i over the entire range of values of the measured signals,

as the threshold value of the magnitude of the radiation signal of the physical field, choose a value from the interval for which the difference in the number of measured signals in this and previous intervals is less than zero, and the difference in the number of measured signals in this and subsequent intervals is greater than zero.

After calculating the difference in the number of measured signals in the subsequent and previous intervals over the entire range of values of the values of the measured signals, the following actions are performed:

a priori determine that the signal in the defective area is smaller in magnitude of the signal in the quality area.

и

, здесь1. Ask

and

, here

- вероятность ложного обнаружения дефектов,

- the probability of false detection of defects,

- вероятность пропуска дефектов,

- probability of missing defects,

2. Measure the number of signals falling into each interval - K _i ,

3. Measure the difference of the signals falling into each interval between adjacent intervals: ΔK _i = K _{i + 1} -K _i .

, удовлетворяющего следующим условиям:4. Measure the magnitude of the signal in the center of the interval, which falls the largest number of signals of the defective area -

satisfying the following conditions:

, удовлетворяющего следующим условиям:5. Measure the magnitude of the signal in the center of the interval over which the largest number of signals of the high-quality section

satisfying the following conditions:

i is the number of the measurement interval.

, и номер интервала n, соответствующего 0,63

.6. Determine the number of the interval m corresponding to a value of 0.63

, and the interval number n corresponding to 0.63

.

7. Determine the rms value of the distribution of signals in the defective areas:

8. Determine the rms value of the distribution of signals in the defective areas:

и

, например,9. Set the ratio between the values:

and

, eg,

The value of χ is determined by the tasks facing the control: either to identify all defects, but at the same time re-rejection is allowed, i.e. false detection of defects, or to reveal only obvious defects, but at the same time partial skipping of defects is allowed. The quantity χ is numerically equal to ...

10. Determine the numerical value of the threshold signal U _pores by solving the following equation:

Experimental studies were carried out on structures made of composite materials. The design was a cylindrical product, which was controlled by ultrasonic shadow non-contact method. In FIG. Figure 2 shows a scan of the cylindrical part of the product with the values of the ultrasonic signal printed on it in different colors. For clarity and simplification of experimental research, a controlled product contains artificial defects of various sizes and characteristics. In the process of experimental research, the task was to detect all defects in the product with a probability of at least 0.97 and to determine the probability of rejection.

и определенного по заявляемому способу при условии обнаружения дефектов не менее 0,97

. На фиг. 4 приведена дефектограмма, полученная в результате обработки распределения сигналов (фиг. 3) по способу, определенному в качестве прототипа. На фиг. 5 приведена дефектограмма, полученная в результате обработки распределения сигналов (фиг. 3) по способу, определенному в соответствии с заявляемым способом.In FIG. Figure 3 shows the experimental distribution of the signal over part of the surface of the product in arbitrary units. In FIG. 3 shows the value of the threshold signal determined by the method selected as a prototype

and determined by the claimed method, provided that defects are detected at least 0.97

. In FIG. 4 shows a defectogram obtained as a result of processing the distribution of signals (Fig. 3) according to the method defined as a prototype. In FIG. 5 shows a defectogram obtained as a result of processing the distribution of signals (Fig. 3) according to the method determined in accordance with the claimed method.

The results of experimental studies are shown in table 1.

Experimental studies confirm that the stated goals in the claimed method are fulfilled: the claimed method provides for the identification of defects with a given probability.

Claims (30)

The method of non-destructive quality control of products, according to which the following operations are performed: - scan the surface of the controlled object with information sensors of physical fields, - measure the magnitude of the signals of the radiation of the physical field from each point on the surface of the controlled object, - break down the entire range of values of the signals of the radiation of the physical field according to their values at I intervals, - register the measured signals by belonging to the corresponding intervals, - determine the amount of measured signals at each interval K _i, - calculate the difference in the number of measured signals in the subsequent and previous intervals

over the entire range of values of the measured signals, - as a threshold value of the magnitude of the radiation signal of the physical field, choose a value from an interval for which the difference in the number of measured signals in this and previous intervals is less than zero, and the difference in the number of measured signals in this and subsequent intervals is greater than zero, characterized in that after calculating the difference in the number of measured signals in the subsequent and previous intervals over the entire range of values of the values of the measured signals - a priori determine that the larger is the signal in the defective section or the signal in the high-quality section, it is accepted for definiteness that the signal in the defective section is smaller in magnitude of the signal in the high-quality section, - ask

and

taking into account the control tasks: to detect all defects with a probable rejection or lack of rejection with the probability of missing defects, where

- the probability of false detection of defects,

- probability of missing defects, - additionally measure the magnitude of the signal in the center of the interval, which falls the largest number of signals of the defective area -

satisfying the following conditions:

- additionally measure the magnitude of the signal in the center of the interval, which falls the largest number of signals of the high-quality section -

satisfying the following conditions:

where i is the number of the measurement interval, - measure the number of the interval m corresponding to a value of 0.67

, and the interval number n corresponding to 0.67

, - additionally measure the magnitude of the signal in the center of the interval m -

and in the center of the interval

, - determine the rms value of the distribution of signals in defective areas:

- determine the rms value of the distribution of signals in high-quality areas:

- set the ratio between the values:

and

in this case, the χ value is determined on the basis of the tasks facing the control: the detection of all defects with an acceptable rejection or the identification of only obvious defects with an acceptable omission of defects, and - determine the numerical value of the threshold signal

by solving the following equation:

.

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