RU2324929C1 - Vibration diagnostic method and equipment for beginning of failure in construction elements - Google Patents

Abstract

FIELD: exploitation, diagnosis.

SUBSTANCE: firstly the location of possible failure of an element is determined based on the design details and experience of failure of similar structures. A vibration sensor is placed there and vibration is initiated on the control element from an independent vibration source, that can be placed on an part of the element. The accuracy of the sensor is determined and corrected by analysing vibration amplitude. The vibration frequency is measured and mutually analysed periodically at equal intervals and the moment at which any deviation is observed indicate the beginning of crack development. This is determined based on the dynamics of vibration dynamics change, rate of crack development and its indication.

EFFECT: ensuring authenticity and information on the moment of crack development and distribution dynamics.

Description

The invention relates to the field of non-destructive testing and technical diagnostics.

Closest to the invention is a vibrational method for diagnosing the onset of the fracture process in the structural members of an object, which consists in the fact that using vibration sensors installed on the diagnosed object, the vibration changes are recorded after cracks or other violations of the continuity of the material of the structural element of the object are detected, at the initial stage the place of possible destruction of the structural element of the object based on knowledge of the design features, based on the experience of destruction of similar structures, on the basis of engineering calculations, studies, after which two or more identical vibration sensors are installed on a serviceable object in the place of possible destruction, whose signals resulting from the functioning of the object or the influence of an independent vibration source installed on the object are then compared with each other in any order with using any means of comparison, and if, when the structural element controlled by the sensors is in good condition, the comparison means will give information about the equality of the sensor signals, h о qualifies as the absence of signs of destruction, the object is put into operation, but if the structural element controlled by the sensors is in good condition, the signals from different sensors differ from each other so much that the means of comparison signal the presence of an imbalance of the compared signals, the sensor signals are balanced, for which the signal each sensor by any means is multiplied by its weight coefficient, as a result of which the sensor signals are aligned with each other and the means of comparison give information about the equality of the sensor signals, which qualifies as the absence of signs of destruction in the zone controlled by the sensors, then after balancing the object is put into operation and, if during the operation in the zone controlled by sensors there are cracks in the material - precursors of destruction, they change the propagation conditions of vibration waves in the sensor installation area, which leads to an imbalance in the sensor signals, and the comparison tools provide information about the inequality of the sensor signals, which qualifies cited as the beginning of the destruction process of a controlled structural element of an object, on the basis of practical experience, engineering calculations, studies establish an acceptable threshold value of the difference of the compared sensor signals, the excess of which during operation of the object is qualified as the beginning of the destruction process, about which a warning signal is issued, while the threshold function element with an adjustable threshold that controls the excess of the threshold value of the difference of the compared sensor signals can be implemented by any means, informative frequencies are extracted from the sensor signals using filters, which contain information about changes in vibrational vibrations associated with the appearance of cracks in the sensor installation area, and then they use only these components of the sensor signals for subsequent processing steps, such as balancing, comparison, comparing the comparison results with a threshold value, the signals of the vibration sensors with the help of analog-to-digital converters are converted into a digital form of presentation and all further signal processing is carried out on a microcontroller or any other device for processing digital information by software, including extracting informative frequencies from common signals, balancing, comparing, comparing the comparison results with a threshold value and issuing a signal warning about the appearance of cracks if there has been an excess of the threshold, that qualify as the beginning of the destruction process, to create vibrational vibrations in a controlled structural element use any independent Source of the vibrations, which is mounted on an object anywhere (RF patent for invention №2284518, Cl. IPC G01N 29/04 (2006.01), G01M 7/00 (2006.01), published September 27, 2006).

Closest to the invention is a diagnostic device for the beginning of the destruction process in the structural elements of an object, consisting of two vibration sensors, analog-to-digital converters, a microcontroller, an independent source of vibrational vibrations, which is installed on the object anywhere, and the signals of vibrational sensors using analog-digital converters are converted into digital form of presentation and all further signal processing is carried out on the microcontroller by software mi, including the selection of informative frequencies, balancing, comparing signals, comparing the comparison results with a threshold value and outputting a signal warning of the appearance of cracks if there is an excess of the threshold value (RF Patent for invention No. 2284518, class IPC G01N 29/04 (2006.01), G01M 7/00 (2006.01), published September 27, 2006).

The disadvantages of this method and device are the lack of the ability to check the health of the vibration sensor and the need for periodic balancing of the output signals of the sensors when the structural member is in good condition, in addition, monitoring of the dynamics of the crack magnitude is not provided.

The need for balancing the output signals of the sensors due to the following reasons. In the general case, objects can significantly differ from each other both in size and in design complexity. Therefore, a situation is possible when the signals of sensors installed in the control zone at serviceable objects will differ from each other. The reason may be the design features of the object, the difference in the placement of sensors and many other reasons, even such as the presence of permissible, in some cases, discontinuities in the material.

In order to exclude the influence of such reasons that can cause an imbalance in the sensor signals, but not related to the beginning of the destruction process, and fix the ratio of sensor signals when the structural element is in good condition, the sensor signals are balanced. Why, in order to equalize the signals, the signal of each sensor is multiplied by its own weight coefficient.

To exclude the balancing process, a method based on a temporary analysis of the sensor output signal is proposed.

The purpose of the invention is to increase the reliability and information content in determining both the moment of occurrence and the dynamics of crack propagation by determining vibration frequencies at regular intervals and comparing them with each other and determining the dynamics of changes in the difference in vibration frequencies relative to two specified values.

To achieve the technical result of the invention in a vibrational method for diagnosing the beginning of the destruction process in the structural elements of the object, which consists in determining the place of possible destruction at the initial stage on the basis of knowledge of the structural features and the experience of the destruction of similar structures, in installing a vibration sensor in place of the possible destruction of the element of the diagnosed object, creating vibrational vibrations in a controlled structural element using any independent source of vibration oscillations, which are installed on the object at any place, additionally determine the health of the vibration sensor based on the analysis of the amplitude of vibration and provide an indication of the health of the sensor, periodically at equal intervals measure the frequency of the vibrations, and their mutual analysis, the moment of occurrence of the inequality qualifies as the beginning of the process of destruction of the controlled structural element of the object, and provide an indication of the moment of occurrence of a crack, determined on the basis of the dynamics of changes in different STI vibration frequency of the speed of the crack and its indication.

To implement the proposed method in the device for diagnosing the beginning of the destruction process in the structural elements of the object consisting of the studied object structure, mechanically connected with the pathogen and the vibration sensor, an additional signal processing unit, a sensor health indicator, a crack appearance indicator, a crack change rate indicator, and outputs vibration sensor and vibration exciter are connected respectively to the first and second inputs of the signal processing unit, the first, second, third Exit of which are connected respectively to the input indicator serviceability vibration sensor to an input indicator crack occurrence, with the input velocity change indicator value crack.

In addition, the signal processing unit consists of the first, second, third threshold devices, the first, second, third, fourth AND elements, the first, second, third and fourth AND elements, the shift register, the pulse generator, the first, second and third counters , the first and second subtracting devices, the first and second differentiating circuits, the delay line, the OR element, the trigger, the divider, the signal setter, the “Reset” button, the first and second inputs of the signal processing unit being connected respectively to the first input the house of the first threshold device and through the first AND-NOT element with the second input of the first AND element, the first input of which is connected to the output of the first threshold device, the second input of which is connected to the first output of the signal setter, the output of the first threshold device is simultaneously the first output of the signal processing unit, the output of the first element And is connected to the first input of the shift register, the second input of which is connected to the output of the first differentiating circuit, the output of which is simultaneously connected to the second inputs of the first , of the second, third counters and the OR element, when the “Zero” button is pressed, the signal is fed to the input of the first differentiating circuit, the first, second, third and fourth outputs of the shift register are connected respectively to the second and, through the second AND-NOT element, the first input of the second element And, with the second and through the third element AND NOT the first input of the third element And, the pulse generator is connected to the third inputs of the second, third and fourth elements And, the outputs of the second and third element And are connected respectively through the first and second count sensors with the first and second inputs of the first subtractor, the output of which is simultaneously the second output of the information processing unit and is connected to the input of the delay line and the first inputs of the second and third threshold devices, the second inputs of which are connected respectively to the second and third outputs of the signal setter, the outputs of the second and of the third threshold devices, respectively, through a trigger and a fourth AND element NOT connected to the first and second inputs of the fourth And element, the output of which through a third counter is connected to rvym divider input, a second input of which is connected via a second subtractor to the second and third outputs of the set point signal, the output of the delay line via the second differentiating circuit and the first input of the OR element is connected to the second input flip-flop, the divider output is a third output of the signal processing unit.

In addition, the signals of vibration sensors using analog-to-digital converters of the ADC are converted into digital representations and all further signal processing is carried out on a microcontroller or any other device for processing digital information by software, including the formation of three preset signals, comparing the vibration amplitude with the first preset value and the issuance of information about the health of the vibration sensor when the first preset value is exceeded, the measurement of vibration frequencies at regular intervals time, comparing the vibration frequencies with each other and in the case of the appearance of a difference signal, which qualifies as the beginning of the fracture process, providing an indication of the appearance of a crack, assessing the dynamics of crack development based on the dynamics of the difference in the frequency of vibrations ΔF relative to two specified values.

New features that have significant differences in the method is the following set of actions.

1. Determine the health of the vibration sensor based on the analysis of the amplitude of vibration.

2. Indicate the health of the sensor.

3. Measure vibration frequencies periodically, at regular intervals, and compare them with each other.

4. Determine the moment of occurrence of frequency inequality and qualify this as the beginning of the process of destruction of the controlled structural element of the object.

5. Indicate the moment of occurrence of the crack.

6. Determine the rate of crack development based on the dynamics of changes in the frequency of vibration.

7. Carry out an indication of the rate of crack development.

The salient features of the device is the signal processing and communication unit between known and new elements.

In Fig.1 shows a structural diagram of the device, Fig.2 is a structural diagram of a signal processing unit, Fig.3 is a microprocessor operation algorithm, Fig.4 is a vibration frequency measurement algorithm.

The diagnostic device for the beginning of the destruction process in the structural elements of the object consists of the investigated structure 1 of the object, mechanically connected with the pathogen 2 oscillations of the sensor 3 vibration, signal processing unit 4, indicator 5 health sensor, indicator 6 occurrence of cracks, indicator 7 of the rate of change of cracks, and the sensor output vibration is connected to the first input of the signal processing unit, the second input of which is connected to the output of the exciter 2, the first, second, third outputs of the signal processing unit 4 s, respectively, with the input of indicator 5 of serviceability of the vibration sensor, with the input of indicator 6 of the appearance of a crack, with the input of indicator 7 of the rate of change of the magnitude of the crack.

Signal processing unit 4 consists of the first 8, second 9, third 10 threshold devices, the first 11, second 12, third 13, fourth 14 AND elements, the first 15, second 16, third 17 and fourth 18 NAND elements, shift register 19 , 20 pulse generator, first 21, second 22 and third 23 counters, first 24 and second 25 subtracting devices, first 26 and second 27 differentiating circuits, delay lines 28, OR element 29, trigger 30, divider 31, signal generator 32, buttons 33 "Zero", and the first and second inputs of block 4 signal processing are connected respectively with the first input of the first 8 threshold device and through the first 15 element AND NOT with the second input of the first 11 element AND, the first input of which is connected to the output of the first 8 threshold device, the second output is connected to the first output of the signal generator 32, the output of the first 8 threshold of the device is the first output of the signal processing unit 4, the output of the first 11 AND element is connected to the first input of the shift register 19, the second input of which is connected to the output of the first 26 differentiating amplifier, the output of which is simultaneously connected to the second inputs of the first 21, second 22, third 23 counters and the OR element 29, the first, second, third and fourth outputs of the shift register 19 are connected respectively to the second and through the second 16 AND-NOT element with the first input of the second 12 AND element, with second and through the third 17 element AND NOT the first inputs of the third 13 elements And, the pulse generator 20 is connected to the third inputs of the second 12, third 13 and fourth 14 elements And, the outputs of the second 12 and third 13 elements And are connected respectively through the first 21 and second 22 first and second counters the input inputs of the first 24 subtractor, the output of which is simultaneously the second output of the information processing unit 4 and connected to the input of the delay line 28 and the first inputs of the second 9 and third 10 threshold devices, the second inputs of which are connected respectively to the second and third outputs of the signal generator 32, the outputs the second 9 and third 10 threshold devices, respectively, through a trigger 30 and a fourth 18 AND-NOT element connected to the first and second inputs of the fourth 14 AND element, the output of which through the third 23 counter is connected to the first the output of the divider 31, the second input of which is connected through the second 25 subtractor to the second and third outputs of the signal generator 32, the output of the delay line 28 through the second 27 differentiating circuit and the first input of the OR element 29 is connected to the second input of the trigger 30, the first output of the signal generator 32 through the “Reset” button 33 is connected to the input of the first 26 differentiating circuit, the output of the divider 31 is the third output of the signal processing unit 4.

The device operates as follows.

First, the device is prepared for operation, when the “Reset” button 33 is pressed, the signal enters the input of the first 26 differentiating circuit, from the output of which the reset signal enters simultaneously the second inputs of the shift register 19, the first 21, the second 22, the third 23 counters and the OR element 29 , the output of which is supplied to the second input of the trigger 30 (figure 2).

Under the action of the pathogen 2 oscillations on the studied structure 1 of the object, vibrational vibrations occur, which from the vibration sensor 3 are fed to the first input of the signal processing unit 4, the second input of which receives a signal from the output of the pathogen 2 of the oscillations (Fig. 1).

The signals through the first and second inputs of the signal processing unit 4 are received respectively at the first input of the first 8 threshold device and through the first 15 element AND NOT at the second input of the first 11 AND element, the first input of which receives signals from the output of the first 8 threshold device the level of the signal supplied to the second input from the first output of the signal setter 32.

The signal from the output of the first 8 threshold device, which is the first output of the signal processing unit 4, is fed to the sensor health indicator 5.

From the output of the first 11 element And the signal is fed to the first input of the shift register 19. The shift register 19 provides a measurement of the vibration frequency at regular intervals.

This is done as follows.

The signals from the first, second outputs of the shift register 19 are supplied to the first and second outputs of the second 12 And element through the second 16 AND-NOT element and directly, thereby providing pulses from the generator 20 through the third input of the And 12 input of the counter 21 providing measurements of the vibration frequency in the first period of time.

In the second period of time, at the time of the arrival of signals from the third input of the shift register 19, the signals are fed to the second input of the third 13 of the And element, the first input of which receives the signal from the output of the AND-NOT 17 element, providing signals from the 20 pulse generator to the second input counter and measuring the frequency of vibration in a second period of time.

Based on the comparison of the measured vibration frequencies in the first and second time interval, the moment of crack occurrence is determined.

The signals from the outputs of the first 21 and second 22 counters are supplied to the first and second inputs of the first 24 subtractor.

In the case of inequality of vibration frequencies, the signal from the output of the first 24 subtractor is fed to the input of the indicator 6 of the presence of a crack.

To determine the dynamics of crack development, the signal from the output of the first 24 subtractor also goes to the input of the delay line 28 and the first inputs of the second 9 and third 10 threshold devices, the second inputs of which receive signals from the second and third outputs of the signal generator 32, respectively.

If the vibration level of two preset values is exceeded, the signals from the output of the second 9 and third 10 threshold devices, respectively, through a trigger 30 and a fourth 18 AND-NOT element enter the first and second inputs of the fourth 14 AND elements, through the third input of which pulses from the generator 20 to the third 23 counter, the output of which a signal proportional to the time interval for changing the vibration frequencies, is fed to the first input of the divider 31, the second input of which receives signals through the second 25 subtractor, which is connected of the second and third outputs of the set point signal 32, whose output signal is supplied to the speed change indicator 7 cracks.

To monitor the process of crack development, the device provides for periodic zeroing of the trigger 30 through the delay line 28 through the second differentiating circuit 27 and the first input of the OR element 29 (Fig. 2).

The signals from the output of the vibration sensor as in the prototype can be converted using analog-to-digital converters into a digital form of presentation and all further signal processing is carried out on the microprocessor by software in accordance with the presented signal processing algorithms (Fig. 3, Fig. 4).

Thus, the proposed method and device can evaluate the operability of the sensor, reliably determine the moment of occurrence of the crack and the dynamics of the magnitude of the crack.

The source of information

RF patent for the invention No. 2284518, class. IPC G01N 29/04 (2006.01), G01M 7/00 (2006.01), publ. 09/27/2006 (prototype).

Claims (4)

1. The vibrational method for diagnosing the beginning of the destruction process in the structural elements of the object, which consists in determining the place of possible destruction of the structural element of the object at the initial stage on the basis of knowledge of the design features and the experience of the destruction of similar structures, installing a vibration sensor in place of the possible destruction of the element of the diagnosed object, creating vibrational vibrations in a controlled structural element by using any independent source of vibrational vibrations that installed on the object in any place, characterized in that the health of the vibration sensor is determined on the basis of the analysis of the amplitude of the vibration and an indication of the health of the sensor is carried out, periodically at equal intervals measure vibration frequencies and their mutual analysis, the moment of occurrence of the inequality is qualified as the beginning of the process of destruction of the controlled element the design of the object and provide an indication of the moment of occurrence of the crack, determined on the basis of the dynamics of changes in the difference in the frequency of the vibration The rate of crack development and its indication. 2. A diagnostic device for the beginning of the fracture process in the structural elements of the object, consisting of the studied object structure, mechanically connected with the pathogen, and a vibration sensor, characterized in that an additional signal processing unit, a sensor health indicator, a crack appearance indicator, a crack change rate indicator are introduced moreover, the outputs of the vibration sensor and the pathogen are connected respectively to the first and second inputs of the signal processing unit, the first, second, third outputs of which oedineny respectively to the input indicator serviceability vibration sensor to an input indicator crack occurrence, with the input velocity change indicator value crack. 3. The device according to claim 2, characterized in that the signal processing unit consists of a first, second, third threshold devices, first, second, third, fourth AND elements, first, second, third and fourth AND-NOT elements, a shift register, pulse generator, first, second and third counters, first and second subtracting devices, first and second differentiating circuits, delay lines, OR element, trigger, divider, signal setter, Zero button, and the first and second inputs of the signal processing unit are connected respectively, with the first input of the first threshold device and through the first AND gate with the second input of the first AND element, the first input of which is connected to the output of the first threshold device, the second input of which is connected to the first output of the signal setter, the output of the first threshold device is simultaneously the first output of the block signal processing, the output of the first element And is connected to the first input of the shift register, the second input of which is connected to the output of the first differentiating circuit, the output of which is simultaneously connected n with the second inputs of the first, second, third counters and the OR element, when you press the "Zero" button, the signal is fed to the input of the first differentiating circuit, the first, second, third and fourth outputs of the shift register are connected respectively to the second and through the second element AND NOT the input of the second element And, with the second and through the third element AND NOT the first input of the third element And, the pulse generator is connected to the third inputs of the second, third and fourth elements And, the outputs of the second and third element And are connected respectively о through the first and second counters with the first and second inputs of the first subtractor, the output of which is simultaneously the second output of the information processing unit and is connected to the input of the delay line and the first inputs of the second and third threshold devices, the second inputs of which are connected respectively to the second and third outputs of the master signals, the outputs of the second and third threshold devices, respectively, through the trigger and the fourth element AND are NOT connected to the first and second inputs of the fourth element And, the output of which through t this counter is connected to the first input of the divider, the second input of which is connected through the second subtractor to the second and third outputs of the signal generator, the output of the delay line through the second differentiating circuit and the first input of the OR element is connected to the second input of the trigger, the output of the divider is the third output of the signal processing unit . 4. The device according to claim 2, characterized in that the signals of the vibration sensors using analog-to-digital converters of the ADC are converted into a digital form of presentation and all further signal processing is carried out on a microcontroller or any other device for processing digital information by software, including the formation of three specified signals , comparing the vibration amplitude with the first preset value and issuing information about the health of the vibration sensor when the first preset value is exceeded, measuring the frequency of radios at regular intervals, a comparison between a vibration frequency, and in case of the difference signal that is classified as the beginning of the destruction process, the implementation of the display of the appearance of cracks, crack development dynamics estimation on the basis of the dynamics of the vibration frequency selective difference ΔF changes relative to the two given values.

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