CN108151870B - Construction quality problem detection method based on frequency response function - Google Patents
Construction quality problem detection method based on frequency response function Download PDFInfo
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Abstract
The invention discloses a construction quality problem detection method based on a frequency response function, and relates to the technical field of mechanical vibration. The method comprises the following steps: determining a region to be detected which may have construction quality problems on an object to be evaluated; respectively applying the same excitation to the object to be evaluated and the qualified construction object to enable the object to be evaluated and the qualified construction object to vibrate, respectively obtaining vibration frequency response functions of an original point and at least one cross point, and calculating to obtain a frequency band root mean square of a vibration frequency response function ratio of the original point and each cross point, wherein each cross point is connected with the original point under the excitation action through a region to be detected; and when the difference value of the frequency band root mean square of the object to be evaluated and the qualified construction object is larger than a set threshold value, judging that the object to be evaluated has the construction quality problem. The invention effectively reduces the influence of human factors caused by excitation applied by different operators and data analysis, so that the analysis result has higher repeatability and consistency, the data analysis is simple, and the method can be used for judging smaller construction quality problems.
Description
Technical Field
The invention relates to the technical field of mechanical vibration, in particular to a construction quality problem detection method based on a frequency response function.
Background
In the construction process of the ship, certain construction quality problems (such as welding defect inspection, composite material adhesion quality inspection, structural connection strength inspection and the like) of the ship structure and the surface need to be detected and identified. At present, the detection aiming at the construction quality problem mostly depends on methods such as ear listening and visual observation, or vibration noise detection is carried out by means of instrument equipment. When the vibration noise detection method is adopted, firstly, a Frequency Response Function (FRF) curve of external excitation is obtained at a position with a construction quality problem, but when data analysis is performed subsequently, comparison is usually performed directly according to a Root Mean Square (RMS) value of a Frequency band of the Frequency Response Function curve or an amplitude value of a typical Frequency. In the conventional vibration noise detection method, not only the test result is affected by human factors caused by excitation applied by different operators, but also the data processing method excessively depends on the engineering experience of data analysts. Therefore, the error of the conventional test and data analysis method is generally considered to be about 1dB, and can reach 2dB in some cases, so that the conventional vibration noise detection method can only identify a larger construction quality problem, but is not sensitive enough to a fine construction quality problem, and is difficult to judge whether the measurement and analysis error or the construction quality problem, so that the consistency of the analysis result is poor, the evaluation conclusion of the construction quality problem is not uniform, and the engineering application value is low.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a construction quality problem detection method based on a frequency response function, which can effectively reduce the influence of human factors caused by excitation applied by different operators and data analysis, so that the analysis result has higher repeatability and consistency.
The invention provides a construction quality problem detection method based on a frequency response function, which comprises the following steps:
determining a region to be detected which may have construction quality problems on an object to be evaluated;
respectively applying the same excitation to the object to be evaluated and the qualified construction object to enable the object to be evaluated and the qualified construction object to vibrate, respectively obtaining vibration frequency response functions of an original point and at least one cross point, and calculating to obtain a frequency band root mean square of a vibration frequency response function ratio of the original point and each cross point, wherein each cross point is connected with the original point under the excitation action through a region to be detected;
and when the difference value of the frequency band root mean square of the object to be evaluated and the qualified construction object is larger than a set threshold value, judging that the object to be evaluated has construction quality problems.
On the basis of the technical scheme, the method for applying the excitation is a hammering method or a vibration exciter method.
On the basis of the technical scheme, the vibration frequency response function is a displacement frequency response function, a speed frequency response function or an acceleration frequency response function.
On the basis of the technical scheme, a vibration signal in the excitation direction is collected at the origin to obtain a vibration frequency response function;
and arranging a multi-axis vibration sensor at each cross point, acquiring vibration signals in each axis direction, and acquiring a vibration frequency response function according to the vibration signal in the axis direction with the maximum response.
On the basis of the technical scheme, each multi-axis vibration sensor is provided with three mutually perpendicular axial directions, wherein one axial direction is the same as the excitation direction, or the three axial directions are different from the excitation direction.
On the basis of the technical scheme, the frequency band root mean square L of the ratio of the origin to the vibration frequency response function of each cross pointd-RMSThe calculation formula of (2) is as follows:
wherein n is the number of frequency points selected in the frequency band of the vibration frequency response function of the cross point and the origin, each frequency point represents a frequency value, hjkIs the frequency response function value h of the kth frequency point in the jth cross-point vibration frequency response function curveikAnd k is more than or equal to 1 and less than or equal to n, and is the frequency response function value of the kth frequency point in the vibration frequency response function curve of the original point.
On the basis of the technical scheme, the frequency band is determined according to the dynamic characteristics of the object to be evaluated.
On the basis of the technical scheme, the frequency band is 50 Hz-1000 Hz.
On the basis of the technical scheme, the set threshold value is 1 dB.
Compared with the prior art, the invention has the following advantages:
(1) whether the object to be evaluated has the construction quality problem is judged according to the frequency band root mean square of the vibration frequency response function ratio of the origin to the cross point, the influence of human factors caused by excitation applied by different operators and data analysis can be effectively reduced, the analysis result has high repeatability and consistency, and the actual engineering requirement is met.
(2) The detection work can be completed only by two measuring points of a cross point and an original point, the test data amount is small, the data analysis method is simple, the qualified construction objects are directly compared for judgment, the engineering experience of data analysis personnel is not excessively relied, and the reliability of the analysis result is further improved.
(3) The method has the advantages that the sensitivity is high aiming at the construction quality problems of structural welding quality, structural composite material laying, structural connection quality and the like, the difference of the analysis results is larger than the traditional test error range, and the smaller construction quality problem is definitely judged.
Drawings
FIG. 1 is a flow chart of a construction quality problem detection method based on a frequency response function according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a typical metal structure 6, and the locations of the origin, cross-point 1, and cross-point 2 on the metal structure 6;
FIG. 3 is a plot of the vibration acceleration frequency response function ratio spectra at the origin and across point 1;
FIG. 4 is a partial enlarged view (750 Hz-800 Hz) of FIG. 3;
FIG. 5 is a plot of the vibration acceleration frequency response function ratio spectra at the origin and across point 2;
FIG. 6 is a partially enlarged view (750 Hz-800 Hz) of FIG. 5.
In the figure:
1-origin, 2-cross point 1, 3-cross point 2, 4-first region to be detected, 5-second region to be detected, 6-metal structure.
Detailed Description
The basic principle of the method is as follows: based on a frequency response function curve in a vibration testing technology, a cross-point frequency response function ratio and a frequency band root mean square are constructed, according to the theory, for a specific structural object, a frequency response function test of an original point where the excitation is located and a cross-point frequency response function test of the other end of the to-be-detected area are simultaneously carried out on the product which is qualified by aiming at a standard process and a detection flow, the frequency response function ratio and the frequency band root mean square value under a standard construction state are obtained through calculation, and the frequency response function ratio and the frequency band root mean square value are used as a standard sample of the structural object. And aiming at other batches of products of the structural object, measuring points are arranged at the same positions, the same excitation test and data processing method is adopted, and whether the construction quality problem exists is judged by comparing the frequency response function ratio and the frequency band root mean square value.
The invention is described in further detail below with reference to the figures and the embodiments.
Referring to fig. 1, an embodiment of the present invention provides a method for detecting a construction quality problem based on a frequency response function, including the following steps:
s1, determining a to-be-detected area which may have construction quality problems on an object to be evaluated.
And S2, respectively applying the same excitation to the object to be evaluated and the qualified construction object to enable the object to be evaluated and the qualified construction object to vibrate, acquiring vibration frequency response functions of an original point and at least one cross point, and calculating a frequency band root mean square of a vibration frequency response function ratio of the original point to each cross point, wherein each cross point is connected with the original point under the excitation action through the area to be detected. Namely, the origin is the excitation point or the adjacent excitation point, and the cross point is the response point.
The method of applying the excitation is a hammering method or an exciter method. The vibration frequency response function is a displacement frequency response function, a speed frequency response function or an acceleration frequency response function.
The areas to be detected of large structures such as ships and the like are multiple and may not be connected with each other, so that the original points of different areas to be detected can be different.
The method for acquiring the vibration frequency response function of the origin and at least one cross point comprises the following steps: collecting vibration signals in an excitation direction at an origin to obtain a vibration frequency response function, wherein when the excitation applying method is a hammering method, a vibration sensor is arranged at a position adjacent to a hammering point, and the vibration signals in the excitation direction are collected to obtain the vibration frequency response function; when the excitation method is a vibration exciter method, a vibration exciter is used for collecting vibration signals in an excitation direction to obtain a vibration frequency response function. And arranging a multi-axis vibration sensor at each cross point, acquiring vibration signals in each axis direction, and acquiring a vibration frequency response function according to the vibration signal in the axis direction with the maximum response. Specifically, each multi-axis vibration sensor has three mutually perpendicular axial directions, wherein one axial direction is the same as the excitation direction, or the three axial directions are all different from the excitation direction.
For a single point excitation system, the response at a certain measurement point can be calculated by the following formula:
F·H＝A，(1)
and when the vibration response matrix A is respectively vibration displacement, speed or acceleration, the vibration frequency response function is correspondingly respectively a displacement frequency response function, a speed frequency response function or an acceleration frequency response function. The matrix form is:
n is the number of frequency points selected in the frequency band of the vibration frequency response function, each frequency point represents a frequency value, hkIs the frequency response function value of the k-th frequency point in the vibration frequency response function curve, a1,...,anThe motion response values of the 1 st, the right and the n frequency points in the vibration frequency response function curve respectively are k being more than or equal to 1 and less than or equal to n, so that the vibration frequency response function ratio l of the system at a certain frequency point (the frequency value is f) between the ith measuring point and the jth measuring pointdCan be expressed as:
wherein, the ith measuring point is an origin point, the origin point is an excitation point or an adjacent excitation point, the jth measuring point is a response point of excitation, namely a cross point, and when the frequency value is f, h isiIs the value of the vibration frequency response function of the ith measuring point, hjThe value of the vibration frequency response function from the excitation point to the jth measurement point, aiIs the vibration response value of the ith measuring point, ajThe vibration response value of the jth measuring point is obtained.
From the above analysis, the root mean square L of the frequency band of the ratio of the origin to the vibration frequency response function of each cross-pointd-RMSThe calculation formula of (2) is as follows:
wherein n is the number of frequency points selected in the frequency band of the vibration frequency response function of the cross point and the origin, each frequency point represents a frequency value, hjkIs the frequency response function value h of the kth frequency point in the jth cross-point vibration frequency response function curveikAnd k is more than or equal to 1 and less than or equal to n, and is the frequency response function value of the kth frequency point in the vibration frequency response function curve of the original point. The frequency band is determined according to the dynamic characteristics of the object to be evaluated, and may be different for different construction objects, and in general, the frequency band may be 50Hz to 1000Hz, but for small and rigid structures, the upper limit frequency of the frequency band may reach 2000Hz or above, and for some special structures, the lower limit frequency of the frequency band may be 5 Hz.
And S3, judging that the construction quality problem exists in the object to be evaluated when the difference value of the frequency band root-mean-square of the vibration frequency response function ratio of the object to be evaluated and the qualified construction object is larger than a set threshold value. The threshold value is set to 1 dB.
Whether the object to be evaluated has the construction quality problem is judged according to the frequency band root mean square of the vibration frequency response function ratio of the origin to the cross point, the influence of human factors caused by excitation applied by different operators and data analysis can be effectively reduced, the analysis result has high repeatability and consistency, and the actual engineering requirement is met.
The detection work can be completed only by two measuring points of a cross point and an original point, the test data amount is small, the data analysis method is simple, the qualified construction objects are directly compared for judgment, the engineering experience of data analysis personnel is not excessively relied, and the reliability of the analysis result is further improved.
The method has the advantages that the sensitivity is high aiming at the construction quality problems of structural welding quality, structural composite material laying, structural connection quality and the like, the difference of the analysis results is larger than the traditional test error range, and the smaller construction quality problem is definitely judged.
The above method is specifically described below by the metal structure 6:
referring to fig. 2, the upper surface and the vertical surface of the metal structure 6 are both construction surfaces, and the construction surfaces are laid on the metal body by adhering rubber materials with adhesives.
The specific operation steps are as follows:
1) with the metal structure 6 as an evaluation object, a region to be detected which may have construction quality problems is determined: the upper surface is used as a first area to be detected 4, the vertical surface is used as a second area to be detected 5, therefore, two ends of the upper surface and the lower end of the vertical surface are selected as measuring point positions, wherein the original point 1 and the cross point 2 are located at two ends of the upper surface, at the moment, the cross point 2 and the original point 1 are both located in the first area to be detected 4, and the cross point 3 is located in the second area to be detected 5.
2) Part 3 was determined according to the test of GB/T11349.3-2006 vibration and impact mechanical admittance: the method comprises the steps of finishing vibration acceleration frequency response function tests of an original point 1, a cross point 2 and a cross point 3 by an impact excitation method, wherein hammering excitation is carried out on the original point 1, the excitation direction is perpendicular to the upper surface and downward, and vibration acceleration frequency response functions of the original point 1, the cross point 2 and the cross point 3 are collected and obtained simultaneously.
An acceleration sensor is arranged at an original point 1, acceleration signals in an excitation direction are collected to obtain a vibration acceleration frequency response function, a multi-axis vibration sensor is arranged at a cross point 2 and a cross point 3, vibration signals in each axis direction are collected, and the vibration frequency response function is obtained according to the vibration signal in the axis direction with the largest response. Specifically, each multi-axis vibration sensor has three mutually perpendicular axial directions, and since the origin 1 and the cross point 2 are located at both ends of the upper surface and the cross point 3 is located on the vertical surface, the three axial directions of the multi-axis vibration sensor at the cross point 2 and the cross point 3 may be the same as the excitation direction. In general, of the three acceleration signals acquired across the point 2 and across the point 3, the acceleration signal in the same axial direction as the excitation direction is the largest, and in fig. 2, the axial direction is vertically downward.
When the cross-point is at a particular location, such as when the origin and cross-point are connected by an irregular curved surface, the three axis directions of the cross-point multi-axis vibration sensor may be different from the excitation direction.
And (3) carrying out hammering tests for three times, wherein the two tests are qualified construction objects in a state that the rubber material is completely bonded, two different testers carry out hammering tests at an original point 1, the test results are marked as 1 and 2, and during the third hammering test, part of the rubber material in the first area to be detected 4 and the second area to be detected 5 is subjected to degumming treatment (namely, the upper surface and the vertical surface are respectively subjected to degumming half blocks), and the test results are marked as 1. Therefore, the test results of the target 1 and the target 2 are both based on qualified construction objects, and the test result of the target 1 is based on the object to be evaluated.
3) According to the vibration acceleration frequency response function obtained by each test, the vibration acceleration frequency response function ratio of the origin 1 and the cross point 2 in the frequency band and the vibration acceleration frequency response function ratio of the origin 1 and the cross point 3 are calculated according to the formula (3), and frequency spectrograms of the vibration acceleration frequency response functions are respectively shown in fig. 3 to 6.
4) And (4) calculating the frequency band root mean square of the vibration acceleration frequency response function ratio of each test according to the formula (4).
5) And comparing the vibration acceleration frequency response function ratio and the frequency band root mean square obtained by the 3 times of tests, and judging whether the construction quality of the metal structure 6 has problems or not.
Specifically, the following table 1 is a comparison result of the root mean square of the vibration acceleration frequency response function ratio of the origin 1 to the cross point 2 obtained by the 3 times of tests, and the table 2 is a comparison result of the root mean square of the vibration acceleration frequency response function ratio of the origin 1 to the cross point 3 obtained by the 3 times of tests.
TABLE 1
TABLE 2
As can be seen from the results of table 1 and table 2 and fig. 3 and 5: comparing the test results of the standard 1 and the standard 2, the difference value of the frequency band root mean square of the vibration acceleration frequency response function ratio is less than 1dB, namely two different testers respectively carry out hammering test on the original point 1 of a qualified construction object, the two test results are very close, and the method effectively reduces the influence of human factors caused by excitation applied by different operators.
The data required by the method can be obtained by excitation of a hammering method or a vibration exciter method, only operation is required according to national standard, and analysis result difference is not generated due to the change of input source characteristics caused by the difference of testing personnel. Data post-processing personnel only need to process and analyze the data according to the formulas (3) and (4), so that the degree of human intervention is reduced, the reliability of an analysis result is high, the processing method is simple, and conclusion difference is not generated due to the difference of data testing and post-processing personnel. Therefore, the method has higher repeatability and consistency of analysis results, and can meet engineering use.
Comparing the test results of the target 1 and the target 2 with the test result of the target 1, wherein the difference values of the frequency band root mean square of the vibration acceleration frequency response function ratios of the target 1 and the target 2 and the target 1 reach 3-4 dB. Generally, the error of the conventional test and data analysis method is about 1dB, and the part can reach 2 dB. Therefore, for the same construction quality problem, the error identification of the method can reach 1dB, namely the difference value of the identifiable test result is 1dB, the difference value of the identifiable test result is obviously higher than 1dB due to the influence of human factors in the conventional test and data analysis method, and when the difference value of the test result is 1dB, the data evaluation significance is lost. Therefore, the method has obvious analysis result difference and high evaluation reliability on the construction quality problem.
The present invention is not limited to the above-described embodiments, and it will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the principle of the present invention, and such modifications and improvements are also considered to be within the scope of the present invention. Those not described in detail in this specification are within the skill of the art.
Claims (9)
1. A construction quality problem detection method based on a frequency response function is characterized by comprising the following steps:
determining a region to be detected which may have construction quality problems on an object to be evaluated;
respectively applying the same excitation to the object to be evaluated and the qualified construction object to enable the object to be evaluated and the qualified construction object to vibrate, respectively obtaining vibration frequency response functions of an original point and at least one cross point, and calculating to obtain a frequency band root mean square of a vibration frequency response function ratio of the original point and each cross point, wherein each cross point is connected with the original point under the excitation action through a region to be detected;
when the difference value of the frequency band root mean square of the object to be evaluated and the qualified construction object is larger than a set threshold value, judging that the object to be evaluated has construction quality problems;
and the qualified construction object is a product which is qualified by inspection aiming at the standard process and the detection flow.
2. The method for detecting the construction quality problem based on the frequency response function as claimed in claim 1, wherein: the method of applying the excitation is a hammering method or an exciter method.
3. The method for detecting the construction quality problem based on the frequency response function as claimed in claim 1, wherein: the vibration frequency response function is a displacement frequency response function, a speed frequency response function or an acceleration frequency response function.
4. The method for detecting the construction quality problem based on the frequency response function as claimed in claim 1, wherein:
acquiring a vibration signal in an excitation direction at an origin to obtain a vibration frequency response function;
and arranging a multi-axis vibration sensor at each cross point, acquiring vibration signals in each axis direction, and acquiring a vibration frequency response function according to the vibration signal in the axis direction with the maximum response.
5. The method for detecting the construction quality problem based on the frequency response function as claimed in claim 4, wherein: each multi-axis vibration sensor has three mutually perpendicular axial directions, wherein one axial direction is the same as the excitation direction, or the three axial directions are all different from the excitation direction.
6. The method as claimed in claim 1, wherein the frequency band root mean square L of the vibration frequency response function ratio of the origin to each cross point isd-RMSThe calculation formula of (2) is as follows:
wherein n is the number of frequency points selected in the frequency band of the vibration frequency response function of the cross point and the origin, each frequency point represents a frequency value, hjkIs the frequency response function value h of the kth frequency point in the jth cross-point vibration frequency response function curveikAnd k is more than or equal to 1 and less than or equal to n, and is the frequency response function value of the kth frequency point in the vibration frequency response function curve of the original point.
7. The method for detecting the construction quality problem based on the frequency response function as claimed in claim 1, wherein: the frequency band is determined according to the dynamic characteristics of the object to be evaluated.
8. The frequency response function-based construction quality problem detection method of claim 7, wherein: the frequency band is 50 Hz-1000 Hz.
9. The method for detecting the construction quality problem based on the frequency response function as claimed in claim 1, wherein: the set threshold is 1 dB.
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