CN113533019A - Detection and analysis method for chemical bolt fastening degree based on piezoelectric impedance frequency - Google Patents
Detection and analysis method for chemical bolt fastening degree based on piezoelectric impedance frequency Download PDFInfo
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Abstract
The invention discloses a detection and analysis method of chemical bolt fastening degree based on piezoelectric impedance frequency, which comprises the following steps: s1, adhering a piezoelectric ceramic piece and a chemical bolt through a chemical adhesive phase; s2, inserting one end of a chemical bolt into concrete, and simulating different fastening states by setting different insertion depths of the chemical bolt; s3, carrying out impedance frequency test and drawing force test on the piezoelectric ceramics to obtain a plurality of groups of test data; s4, constructing a piezoelectric ceramic vibration frequency correction impedance frequency and drawing force model based on the test data; s5, analyzing the accuracy of the model by using machine learning to obtain the deviation between the predicted drawing force value and the real drawing force value; and S6, calculating a corrected predicted drawing force value, and comparing the corrected predicted drawing force value with the actually required drawing force to evaluate the fastening degree of the chemical bolt.
Description
Technical Field
The invention relates to the technical field of structural nondestructive testing, in particular to a method for detecting and analyzing the fastening degree of a chemical bolt based on piezoelectric impedance frequency.
Background
The chemical bolt is mainly used for connecting a curtain wall steel keel structure and a building body structure by means of combined action of bond stress and mechanical occlusion force between the chemical bolt and concrete, each mechanical index needs to be calculated according to data provided by manufacturers, and since chemical adhesives produced by various manufacturers are different, the bonding capacity is different, and the performance needs to be carefully verified before use. The chemical bolt is mainly characterized in that the anchor rod and the hole wall are bonded through synthetic resin mortar, so that the anchor rod, the anchoring foundation and an anchored object form a whole, and the effect of fixing a component or improving the bearing capacity of the component is achieved.
Chemical bolts have become more widely used in recent years. Like all materials and structures, in the long-term use process of the chemical bolt, the used chemical rubber pipes, screws, washers, nuts and the like have the phenomena of performance degradation, looseness, corrosion and the like in different degrees, the adhesive force and the fastening force acting on concrete are influenced, the chemical bolt is loosened, and the chemical bolt can fall off under extreme conditions. The loosening and falling of the chemical bolt not only affects the use functions of the chemical bolt, such as anchoring the quality of a new structure and an old structure, but also has the greatest harm of casualties and property loss caused by falling from high altitude.
For the existing solution to the above problems, on one hand, a design method, a construction and installation technology and the like are improved, and on the other hand, the existing chemical bolts need to be regularly detected in a large scale, especially the chemical bolts which exceed the design service life and are affected by sunlight, humid rain and strong wind for a long time in the use process. However, the method is currently applicable to chemical bolts, and has very few simple, efficient and reliable loosening and falling risk detection methods. A method based on measuring impedance frequency is a chemical bolt fastening degree detection method proposed by scholars in recent years. The method has the main principle that: the looseness of the chemical bolt changes the vibration constraint condition of the chemical bolt, and the change of the vibration constraint condition influences the vibration impedance frequency of the piezoelectric ceramic bonded with the chemical bolt. Therefore, the fastening degree and the falling risk of the chemical bolt are analyzed by measuring the impedance value of the piezoelectric ceramic bonded with the chemical bolt and the rule of the change of the fastening state of the bolt.
However, in practical applications, the initial impedance frequency of the chemical bolts is often unknown, and in this case, it is generally assumed that only a small number of chemical bolts in a large number of chemical bolts with the same size will have a risk of falling off in the same batch of tests, and at this time, a small number of chemical bolts with abnormal impedance frequency can be selected through transverse comparison, and the falling off risk is considered to be large. However, the above method cannot solve many more common and complicated situations in practical engineering application, such as different sizes of a large number of chemical bolts, different use conditions, different aging degrees of structural adhesives for fixing the chemical bolts, different environmental temperatures during testing, and the like. The above factors all affect the impedance frequency of the chemical bolt to a certain extent, thereby affecting the accuracy of the falling risk judgment.
The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
Disclosure of Invention
The present invention is directed to a method for detecting and analyzing the degree of fastening of a chemical bolt based on piezoelectric impedance frequency, which can solve the above-mentioned problems of the prior art.
In order to achieve the above object, the present invention provides a method for detecting and analyzing the fastening degree of a chemical bolt based on piezoelectric impedance frequency, comprising the steps of:
s1, adhering a piezoelectric ceramic piece and a chemical bolt through a chemical adhesive phase;
s2, inserting one end of a chemical bolt into concrete, and simulating different fastening states by setting different insertion depths of the chemical bolt;
s3, carrying out impedance frequency test and drawing force test on the piezoelectric ceramics to obtain a plurality of groups of test data;
s4, constructing a piezoelectric ceramic vibration frequency correction impedance frequency and drawing force model based on the test data;
s5, analyzing the accuracy of the model by using machine learning to obtain the deviation between the predicted drawing force value and the real drawing force value;
and S6, calculating a corrected predicted drawing force value, and comparing the corrected predicted drawing force value with the actually required drawing force to evaluate the fastening degree of the chemical bolt.
In one embodiment of the present invention, the insertion depth of the chemical bolt is set within a range of: 30-110mm, at least every 5mm depth, at least two sets of tests are performed at each depth.
In an embodiment of the present invention, the step S3 of performing the impedance frequency test and the drawing force test on the piezoelectric ceramic to obtain a plurality of sets of test data includes: and measuring the impedance spectrum of the piezoelectric ceramic after the chemical adhesive is cured for 24 hours by using a piezoelectric impedance tester to obtain a frequency peak value, testing the drawing force after the impedance spectrum is tested, and measuring the maximum drawing force in the drawing process of the chemical bolt with the corresponding depth, wherein the maximum drawing force corresponds to the real drawing force value of the insertion depth.
In one embodiment of the present invention, in step S4, constructing the model of the vibration frequency correction impedance frequency and the pulling force of the piezoelectric ceramic based on the test data includes:
the predicted drawing force value is obtained by the following formula:
y-2.26 a-1.08b-0.01a2+0.025ab-0.13b2-27.18 … … formula (1);
wherein a is a depth value of the target chemical bolt inserted into the concrete and is measured in mm, b is an impedance difference value between an impedance value of the piezoelectric ceramic when the piezoelectric ceramic is just adhered with the chemical glue and is not cured and an impedance value measured after the chemical glue is cured for 24 hours, and is measured in MHz, y is a predicted drawing force value of the chemical glue service time and is measured in KN; 27.18 is a correction coefficient.
In an embodiment of the present invention, analyzing the accuracy of the model by machine learning, and obtaining the deviation between the predicted drawing force value and the actual drawing force value includes: and (4) comparing the vibration frequency impedance value of the piezoelectric ceramic piece bonded with the chemical bolt with the impedance value of the chemical bolt before installation to obtain an impedance difference value, obtaining a data distribution diagram of the insertion depth of the chemical bolt and the impedance difference value based on the plurality of groups of test data in the step S3, and if the insertion depth is not at the tested point position, estimating to obtain the impedance difference value of the insertion depth by a linear interpolation method.
In an embodiment of the invention, Python software machine learning analysis is adopted to perform linear regression analysis on multiple groups of drawing force predicted values and real drawing force values to obtain the calculation error of the drawing force of the chemical bolt through the impedance frequency value of the piezoelectric ceramic.
In one embodiment of the present invention, the corrected predicted drawing force value is calculated and compared with the actually required drawing force to evaluate the fastening degree of the chemical bolt: and correcting and calculating the predicted drawing force value according to the deviation of the predicted drawing force value and the real drawing force value to obtain a corrected predicted drawing force value, wherein if the corrected predicted drawing force value is more than twice of the designed axial tension value of the chemical bolt, the chemical bolt has no loosening risk.
In an embodiment of the present invention, before the piezoelectric ceramic plate and the chemical bolt are bonded by the chemical adhesive, the top surface of the chemical bolt is processed to make the top surface of the chemical bolt smooth and free of dust, and the flat surface of the piezoelectric ceramic plate is bonded to the top surface of the chemical bolt by the chemical adhesive.
Compared with the prior art, the method for detecting and analyzing the fastening degree of the chemical bolt based on the piezoelectric impedance frequency has the following advantages: one end of a chemical bolt is inserted into concrete, impedance difference values of the chemical bolts in different fastening states are simulated by setting different insertion depths of the chemical bolts, a plurality of groups of test data are obtained by testing impedance frequency and drawing force of piezoelectric ceramics, machine learning analysis is carried out on the test data, two main factors of the impedance difference values of the chemical bolts are judged, graph data obtained by tests are compared with reference impedance difference values of the chemical bolts with the same size on the basis, and loosening risks of the tested chemical bolts are judged. Compared with the existing method, the method has the advantages of more comprehensive consideration factors, wider applicability, simple operation and no need of changing the use environment of the chemical bolt.
Drawings
Fig. 1 is a flowchart of a method for detecting and analyzing a chemical bolt tightening degree based on a piezoelectric impedance frequency according to an embodiment of the present invention.
Fig. 2 is a schematic view of a connection structure of a piezoelectric ceramic plate and a chemical bolt according to an embodiment of the invention.
Fig. 3A-3B are schematic views of the construction of a chemical bolt according to an embodiment of the present invention inserted into concrete at different depths.
FIG. 4 is a graph of data distribution of different insertion depths and impedance differences for a chemical stud according to one embodiment of the present invention.
FIG. 5 is a graph illustrating an analysis of model accuracy using machine learning, according to an embodiment of the present invention.
Detailed Description
The following detailed description of the present invention is provided in conjunction with the accompanying drawings, but it should be understood that the scope of the present invention is not limited to the specific embodiments.
Throughout the specification and claims, unless explicitly stated otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element or component but not the exclusion of any other element or component.
Example 1
As shown in fig. 1, the method for detecting and analyzing the fastening degree of a chemical bolt based on piezoelectric impedance frequency of the present invention includes the following steps:
step S1, as shown in figures 2, 3A and 3B, the piezoelectric ceramic plate 1 and the chemical bolt 2 are bonded through chemical glue 3.
Specifically, before the piezoelectric ceramic piece 1 is bonded with the chemical bolt 2 through the chemical glue 3, the top surface of the chemical bolt 2 is processed, so that the top surface of the chemical bolt 2 is smooth and free of dust, and the flat surface of the piezoelectric ceramic piece 1 is bonded with the top surface of the chemical bolt 2 through the chemical glue (super glue).
And S2, inserting one end of the chemical bolt into the concrete, and simulating different fastening states by setting different insertion depths of the chemical bolt.
Specifically, the range of the insertion depth of the chemical bolt 2 is set as follows: 30-110mm, at least every 5mm depth, at least two sets of tests are performed at each depth.
And S3, carrying out impedance frequency test and drawing force test on the piezoelectric ceramics to obtain multiple groups of test data.
Specifically, a piezoelectric impedance tester is used for measuring the impedance spectrum of the piezoelectric ceramic after the chemical adhesive is cured for 24 hours, so as to obtain a frequency peak value, and after the impedance spectrum is tested, the drawing force is tested, so that the maximum drawing force in the drawing process of the chemical bolt with the corresponding depth is measured, and the maximum drawing force corresponds to the real drawing force value of the insertion depth. In the piezoelectric impedance frequency spectrum and frequency test, the used instrument is a general 4294A impedance test analyzer, has the characteristics of rapidness and stability, and can finish the impedance spectrum test and the frequency peak value reading only by connecting two ends of the electrode of the piezoelectric ceramic piece with the port of the tester.
And S4, constructing a piezoelectric ceramic vibration frequency correction impedance frequency and drawing force model based on the test data.
Specifically, various factors may affect the impedance frequency of the chemical bolt, and the invention considers two main factors: the insertion depth of the chemical bolt and the bonding strength of the chemical glue. The insertion depth of the chemical bolt and the reduction of the bonding strength of the chemical glue can cause the loosening of the chemical bolt, reduce the constraint on the piezoelectric ceramic piece and further cause the change of the impedance value of the vibration frequency.
The method obtains the predicted value of the drawing force by the following formula:
y-2.26 a-1.08b-0.01a2+0.025ab-0.13b2-27.18 … … formula (1);
wherein a is a depth value of the target chemical bolt inserted into the concrete and is measured in mm, b is an impedance difference value between an impedance value of the piezoelectric ceramic when the piezoelectric ceramic is just adhered with the chemical glue and is not cured and an impedance value measured after the chemical glue is cured for 24 hours, and is measured in MHz, y is a predicted drawing force value of the chemical glue service time and is measured in KN; 27.18 is a correction coefficient.
And S5, analyzing the accuracy of the model by using machine learning to obtain the deviation between the predicted drawing force value and the real drawing force value.
Specifically, the impedance difference is obtained by comparing the vibration frequency impedance value of the piezoelectric ceramic piece bonded with the chemical bolt with the impedance value of the chemical bolt before installation. Based on the multiple sets of test data in step S3, a data distribution diagram of the chemical bolt insertion depth and the impedance difference is obtained, and as shown in fig. 4, if the insertion depth is not at the tested point position, for example, a depth between the insertion depths corresponding to the two test points, the impedance difference of the insertion depth is estimated by a linear interpolation method. The figure shows that the insertion depth of the chemical bolt is positively correlated with the difference in impedance. The series of tests described above was performed after 24 hours curing of the chemical bolts. When the chemical bolt is fixed for 24 hours, the impedance frequency is already stable, wherein the impedance interpolation and the drawing force are in a nonlinear relation, and a predicted drawing force value needs to be obtained through further calculation of the formula (1).
And S6, calculating a corrected predicted drawing force value, and comparing the corrected predicted drawing force value with the actually required drawing force to evaluate the fastening degree of the chemical bolt.
Example 2
In a preferred embodiment, a Python software machine learning analysis is adopted to perform linear regression analysis on multiple groups of drawing force predicted values and real drawing force values:
and analyzing the following according to the drawing force predicted values and the real drawing force values corresponding to the obtained multiple groups of insertion depths:
correlation between # calculated predicted value and # actual value
fromscipy.statsimportpearsonr
#df_pearson＝data.corr()pccs＝np.corrcoef(y_pred,y_test)
The correlation is considered to be significant if the pearson [ 'predictive value' ], data [ 'real value' ]) # P value is less than 0.05
pearson
Out[43]:
(0.9558095734739029,0.0007698654033839772)
In[44]:
#pccs＝np.corrcoef(y_pred,y_test)
In[45]:
# Picture
plt.figure(figsize＝(10,6))
Title ('model predicted vs. true', fontsize ═ 20)
x＝np.linspace(np.min(y_test),np.max(y_test),100)
y＝x
plt.plot(x,y,'r-')
plt.scatter(y_pred,list(y_test))
Xlabel ('predicted value', fontsize ═ 20)
Yl panel ('true value', fontsize ═ 20)
Text (x 55, y 25, s 'regression coefficient R2:%,% 2 f'% R2, fontsize 20)
Text (x 55, y 18, s 'correlation r 0.955', fontsize 20)
plt.grid()
plt.show()
plt.savefig('./figure1.jpg')
As shown in fig. 5, the straight line in the graph is the predicted drawing force value, the black dot in the graph is the real drawing force value, the calculation error of the drawing force of the chemical bolt obtained through linear regression through the impedance frequency value of the piezoelectric ceramic is obtained, and the correlation coefficient r is 0.955, that is, the error between the predicted value and the real value of the model should be 5%.
And further, according to the deviation between the predicted drawing force value and the real drawing force value, correcting and calculating the predicted drawing force value to obtain a corrected predicted drawing force value, wherein if the corrected predicted drawing force value is more than two times of the designed axial tension value of the chemical bolt, the chemical bolt has no loosening risk.
Example 3
In this embodiment, five chemical bolts with different insertion depths are selected and tested, and the loosening and loosening risk judgment process is as follows:
according to the measurement of the depth position and the impedance difference value of the chemical bolt, five chemical bolts are respectively marked, the depth of the first bolt is 85mm, and the impedance difference value is 10 kHz; the depth of the second bolt is 45mm, and the impedance difference is 1 kHz; the depth of the third bolt is 70mm, and the impedance difference is 4.3 kHz; the depth of the fourth bolt is 75mm, and the impedance difference is 3 kHz; the depth of the fifth bolt is 100mm, and the impedance difference is 1.4 kHz.
And (3) substituting the measured data into a formula (1) for calculation to respectively obtain the predicted values of the drawing force of each chemical bolt. The predicted value of the first bolt drawing force is 71.88kN, the predicted value of the second bolt drawing force is 49.25kN, the predicted value of the third bolt drawing force is 70.32kN, the predicted value of the fourth bolt drawing force is 73.31kN, and the predicted value of the fifth bolt drawing force is 75.54 kN.
After the obtained predicted drawing force value is multiplied by a correction coefficient of 95%, the result is compared with 16kN which is twice of a design value 8KN required by a drawing experiment of M12 × 100mm chemical bolts, and the drawing force values of five test bolts are all larger than 16kN, so that the risk of loosening is avoided.
The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.
Claims (8)
1. A detection and analysis method for the fastening degree of a chemical bolt based on piezoelectric impedance frequency is characterized by comprising the following steps:
s1, adhering a piezoelectric ceramic piece and a chemical bolt through a chemical adhesive phase;
s2, inserting one end of a chemical bolt into concrete, and simulating different fastening states by setting different insertion depths of the chemical bolt;
s3, carrying out impedance frequency test and drawing force test on the piezoelectric ceramics to obtain a plurality of groups of test data;
s4, constructing a piezoelectric ceramic vibration frequency correction impedance frequency and drawing force model based on the test data;
s5, analyzing the accuracy of the model by using machine learning to obtain the deviation between the predicted drawing force value and the real drawing force value;
and S6, calculating a corrected predicted drawing force value, and comparing the corrected predicted drawing force value with the actually required drawing force to evaluate the fastening degree of the chemical bolt.
2. A method for detecting and analyzing the degree of fastening of a chemical bolt based on piezoelectric impedance frequency according to claim 1, wherein the range of the insertion depth of the chemical bolt is set as follows: 30-110mm, at least every 5mm depth, at least two sets of tests are performed at each depth.
3. A method for detecting and analyzing the degree of fastening of a chemical bolt based on piezoelectric impedance frequency according to claim 1, wherein in step S3, the impedance frequency test and the pull-out force test of the piezoelectric ceramic are performed, and the obtaining of the plurality of sets of test data includes: and measuring the impedance spectrum of the piezoelectric ceramic after the chemical adhesive is cured for 24 hours by using a piezoelectric impedance tester to obtain a frequency peak value, testing the drawing force after the impedance spectrum is tested, and measuring the maximum drawing force in the drawing process of the chemical bolt with the corresponding depth, wherein the maximum drawing force corresponds to the real drawing force value of the insertion depth.
4. A method for detecting and analyzing the degree of fastening of a chemical bolt based on piezoelectric impedance frequency according to claim 1, wherein in step S4, the constructing a model of the piezoelectric ceramic vibration frequency correction impedance frequency and the pulling force based on the test data comprises:
the predicted drawing force value is obtained by the following formula:
y＝2.26a-1.08b-0.01a2+0.025ab-0.13b227.18 … … equation (1);
wherein a is a depth value of the target chemical bolt inserted into the concrete and is measured in mm, b is an impedance difference value between an impedance value of the piezoelectric ceramic when the piezoelectric ceramic is just adhered with the chemical glue and is not cured and an impedance value measured after the chemical glue is cured for 24 hours, and is measured in MHz, y is a predicted drawing force value of the chemical glue service time and is measured in KN; 27.18 is a correction coefficient.
5. The method for detecting and analyzing the degree of fastening of a chemical bolt based on piezoelectric impedance frequency according to claim 4, wherein analyzing the accuracy of the model by machine learning, and obtaining the deviation between the predicted value of the pulling force and the true value of the pulling force comprises: and (4) comparing the vibration frequency impedance value of the piezoelectric ceramic piece bonded with the chemical bolt with the impedance value of the chemical bolt before installation to obtain an impedance difference value, obtaining a data distribution diagram of the insertion depth of the chemical bolt and the impedance difference value based on the plurality of groups of test data in the step S3, and if the insertion depth is not at the tested point position, estimating to obtain the impedance difference value of the insertion depth by a linear interpolation method.
6. A method according to claim 5, wherein Python software machine learning analysis is used to perform linear regression analysis on the predicted values and actual values of the pull-out force to obtain the error in calculating the pull-out force of the chemical bolt through the impedance frequency of the piezoelectric ceramic.
7. A detection and analysis method for a chemical bolt fastening degree based on piezoelectric impedance frequency according to claim 6, characterized in that the corrected predicted drawing force is calculated and compared with the actually required drawing force to evaluate the fastening degree of the chemical bolt: and correcting and calculating the predicted drawing force value according to the deviation of the predicted drawing force value and the real drawing force value to obtain a corrected predicted drawing force value, wherein if the corrected predicted drawing force value is more than twice of the designed axial tension value of the chemical bolt, the chemical bolt has no loosening risk.
8. The method according to claim 1, wherein before the piezoelectric ceramic plate and the chemical bolt are bonded together by the chemical adhesive, the top surface of the chemical bolt is processed to make the top surface of the chemical bolt smooth and free of dust, and the flat surface of the piezoelectric ceramic plate is bonded to the top surface of the chemical bolt by the chemical adhesive.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117862263A (en) * | 2024-03-12 | 2024-04-12 | 常州润来科技有限公司 | Copper pipe coil pulling vibration reduction method and system special for heating ventilation |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117862263A (en) * | 2024-03-12 | 2024-04-12 | 常州润来科技有限公司 | Copper pipe coil pulling vibration reduction method and system special for heating ventilation |
| CN117862263B (en) * | 2024-03-12 | 2024-05-24 | 常州润来科技有限公司 | Copper pipe coil pulling vibration reduction method and system special for heating ventilation |
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Effective date of registration: 20220130 Address after: 518000 Luofang Road Central decoration building, Luohu District, Shenzhen City, Guangdong Province Applicant after: CHINA CONSTRUCTION SHENZHEN DECORATION CO.,LTD. Applicant after: China Construction Limited by Share Ltd Address before: 518000 Luofang Road Central decoration building, Luohu District, Shenzhen City, Guangdong Province Applicant before: CHINA CONSTRUCTION SHENZHEN DECORATION CO.,LTD. |