阅读说明：本技术 一种工程结构健康监测装置及方法 (Engineering structure health monitoring device and method ) 是由 张玉龙 罗明璋 黑创 张兴华 马新元 张凡君 苏永刚 刘付刚 张�林 张波 谢小 于 2020-11-14 设计创作，主要内容包括：本发明属于工程结构健康监测技术领域,具体涉及一种工程结构健康监测装置及方法,包括多个阻抗传感器,所述多个阻抗传感器串联组合,所述多个阻抗传感器的谐振峰分布在工程结构的检测频带范围内且谐振峰不重叠。本发明利用有限元数值模拟不同尺寸阻抗传感器的阻抗特征,通过将多个不同谐振峰的阻抗传感器进行串联组合,与常规的单一阻抗传感器相比,大幅拓宽传感器的检测范围,可以通过一次测量,同时获取串联式阻抗传感器阵列中每个传感器的阻抗特征,为阻抗快速检测提供了可靠的方法和技术。(The invention belongs to the technical field of engineering structure health monitoring, and particularly relates to an engineering structure health monitoring device and method. The invention simulates the impedance characteristics of the impedance sensors with different sizes by using finite element numerical values, and greatly widens the detection range of the sensors by combining the impedance sensors with a plurality of different resonance peaks in series compared with the conventional single impedance sensor, can simultaneously acquire the impedance characteristics of each sensor in the series impedance sensor array by one-time measurement, and provides a reliable method and technology for the rapid detection of the impedance.)

1. The utility model provides an engineering structure health monitoring device which characterized in that: the device comprises a plurality of impedance sensors which are combined in series, and resonance peaks of the impedance sensors are distributed in the detection frequency band range of the engineering structure and are not overlapped.

2. An engineering structure health monitoring device according to claim 1, wherein: the impedance sensors comprise piezoelectric ceramics and magnetic steels, and the thicknesses of the magnetic steels in the impedance sensors are different.

3. An engineering structure health monitoring device according to claim 1, wherein: the engineering structure comprises a steel structure, bolts and pipelines.

4. An engineering structure health monitoring device according to claim 1, wherein: the piezoelectric ceramics are barium titanate, lead zirconate titanate or lead magnesium niobate.

5. A health monitoring method for an engineering structure is characterized by comprising the following steps:

step 1) preparing a plurality of impedance sensors with different resonance peaks according to a monitored object to be connected in series to form an engineering structure health monitoring device;

step 2) installing the impedance sensor on the surface of the monitored object, connecting the anode and the cathode of the impedance sensor connected in series by using an impedance analyzer, applying sweep frequency excitation to carry out piezoelectric impedance measurement, wherein the sweep frequency range is consistent with the detection frequency band range of the monitored object;

and 3) when the resonance peak of one or more impedance sensors has frequency shift or peak value change, judging that the installation position of the impedance sensor has damage.

6. The method for monitoring the health of an engineering structure according to claim 4, wherein: the specific process of step 1) is as follows:

(1) selecting a detection frequency band range according to a monitored object, and determining a plurality of resonance peaks in the detection frequency band range;

(2) establishing an impedance finite element calculation model, simulating the impedance characteristics of different sizes and different materials aiming at each resonance peak value, and selecting the size and the material with high responsiveness to prepare each impedance sensor;

(3) and connecting the impedance sensors in series through a lead and a binding clip.

7. The method for monitoring the health of an engineering structure according to claim 6, wherein: the specific process of the step (2) is as follows: the method comprises the steps that firstly, finite element software carries out geometric modeling on a monitored object according to the size and the material of the monitored object, then, grid division is carried out, then, impedance sensor modeling is carried out according to the size and the material of different impedance sensors, the impedance sensors are installed on the same position of the surface of the monitored object in a simulation mode, then, constraint and load are applied, finally, the impedance characteristics of different sizes and different materials are obtained through numerical simulation, and the size and the material with high responsiveness are selected to prepare each impedance sensor.

8. The method for monitoring the health of an engineering structure according to claim 6, wherein: after the impedance sensors are connected in series through a lead and a binding clip, an impedance analyzer is used for analyzing the impedance characteristics of the impedance sensors, and the impedance characteristics are compared with the detection frequency band range in the step (1), if all the resonance peaks are in the detection frequency band range, the preparation of the process structure health monitoring device is completed, if some or more resonance peaks are not in the detection frequency band range, the step (2) is repeated, the size and the material are changed for optimization, and until all the resonance peaks are in the detection frequency band range.

Technical Field

The invention belongs to the technical field of engineering structure health monitoring, and particularly relates to an engineering structure health monitoring device and method.

Background

Since the advent of piezoelectric ceramics (PZT), the application of PZT as a basic element of a structural health monitoring technology becomes a hot spot for engineering structure research due to the characteristics of low cost, small size, high bandwidth, integration of sensing and driving, energy collection, availability of different sizes and shapes and the like.

At present, relevant researches of domestic and foreign researchers on health monitoring and damage identification of civil engineering structures by using piezoelectric ceramics can be mainly divided into two categories: the impedance method, which is one of the technical means of active monitoring, is widely applied mainly to the active monitoring method and the passive monitoring method. The basic principle of the impedance method is that the piezoelectric ceramics and a structure to be detected can be coupled with each other, the mechanical impedance of the structure is coupled into the electrical impedance of the piezoelectric ceramics, and the change of the electrical impedance of the piezoelectric ceramics can indirectly reflect the change of the mechanical impedance of the structure caused by damage. The most important part of the impedance technique is the measurement of the impedance or admittance of the structure under test.

At present, sensors for impedance measurement usually have only one resonance peak, and when a measured object is sensitive to the resonance peak, the state change of the measured object causes the characteristic change of the resonance peak. The position of the resonance peak of the impedance sensor is determined by the size of the sensor, the detection range of a single sensor is limited, the single sensor is only sensitive to structural changes near the frequency, and other structural changes cannot be detected, so that the engineering application requirements of structural health monitoring cannot be met.

Disclosure of Invention

The invention aims to provide an engineering structure health monitoring device, which overcomes the technical problems in the prior art.

Another object of the present invention is to provide a method for monitoring the health of an engineering structure, which can accurately monitor the health of the structure.

Therefore, the technical scheme provided by the invention is as follows:

an engineering structure health monitoring device comprises a plurality of impedance sensors which are combined in series, and resonance peaks of the impedance sensors are distributed in a detection frequency band range of an engineering structure and are not overlapped.

The impedance sensors comprise piezoelectric ceramics and magnetic steels, and the thicknesses of the magnetic steels in the impedance sensors are different.

The engineering structure comprises a steel structure, bolts and pipelines.

The piezoelectric ceramics are barium titanate, lead zirconate titanate or lead magnesium niobate.

A health monitoring method for an engineering structure comprises the following steps:

step 1) preparing a plurality of impedance sensors with different resonance peaks according to a monitored object to be connected in series to form an engineering structure health monitoring device;

step 2) installing the impedance sensor on the surface of the monitored object, connecting the anode and the cathode of the impedance sensor connected in series by using an impedance analyzer, applying sweep frequency excitation to carry out piezoelectric impedance measurement, wherein the sweep frequency range is consistent with the detection frequency band range of the monitored object;

and 3) when the resonance peak of one or more impedance sensors has frequency shift or peak value change, judging that the installation position of the impedance sensor has damage.

The specific process of step 1) is as follows:

(1) selecting a detection frequency band range according to a monitored object, and determining a plurality of resonance peaks in the detection frequency band range;

(2) establishing an impedance finite element calculation model, simulating the impedance characteristics of different sizes and different materials aiming at each resonance peak value, and selecting the size and the material with high responsiveness to prepare each impedance sensor;

(3) and connecting the impedance sensors in series through a lead and a binding clip.

The specific process of the step (2) is as follows: the method comprises the steps that firstly, finite element software carries out geometric modeling on a monitored object according to the size and the material of the monitored object, then, grid division is carried out, then, impedance sensor modeling is carried out according to the size and the material of different impedance sensors, the impedance sensors are installed on the same position of the surface of the monitored object in a simulation mode, then, constraint and load are applied, finally, the impedance characteristics of different sizes and different materials are obtained through numerical simulation, and the size and the material with high responsiveness are selected to prepare each impedance sensor.

After the impedance sensors are connected in series through a lead and a binding clip, an impedance analyzer is used for analyzing the impedance characteristics of the impedance sensors, and the impedance characteristics are compared with the detection frequency band range in the step (1), if all the resonance peaks are in the detection frequency band range, the preparation of the process structure health monitoring device is completed, if some or more resonance peaks are not in the detection frequency band range, the step (2) is repeated, the size and the material are changed for optimization, and until all the resonance peaks are in the detection frequency band range.

The invention has the beneficial effects that:

according to the engineering structure health monitoring device provided by the invention, the impedance sensors with different resonance peaks are connected in series, so that the detection range of the sensors is greatly widened.

The method can simultaneously acquire the impedance characteristics of each sensor in the series impedance sensor array through one-time measurement, and provides a reliable method and technology for rapid impedance detection.

The following will be described in further detail with reference to the accompanying drawings.

Drawings

FIG. 1 is a schematic diagram of geometric modeling according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of an embodiment of the present invention for partitioning a grid;

FIG. 3 is a schematic illustration of the application of restraint and load by an embodiment of the present invention;

FIG. 4 is a graph of impedance characteristics for an embodiment of the present invention;

FIG. 5 is a schematic connection diagram of an embodiment of an engineering structure health monitoring device according to the present invention;

FIG. 6 is an impedance profile of an engineered structure health monitoring device of the present invention;

FIG. 7 is a graph of impedance characteristics for a fully tightened bolt in accordance with an embodiment of the present invention;

fig. 8 is a characteristic diagram of the impedance when the bolt of the embodiment of the present invention is loosened.

In the figure:

description of reference numerals:

1. a first impedance sensor; 2. a second impedance sensor; 3. a third impedance sensor; 4. an impedance sensor IV; 5. and (4) conducting wires.

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.

The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention.

Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.

Example 1:

the embodiment provides an engineering structure health monitoring device, which comprises a plurality of impedance sensors, wherein the impedance sensors are combined in series, and resonance peaks of the impedance sensors are distributed in a detection frequency band range of an engineering structure and are not overlapped.

Compared with the conventional single impedance sensor, the engineering structure health monitoring device provided by the invention has the advantages that the series impedance sensor can greatly widen the detection range of the sensor.

Example 2:

on the basis of embodiment 1, this embodiment provides an engineering structure health monitoring device, impedance sensor includes piezoceramics and magnet steel, the magnet steel thickness in a plurality of impedance sensor is different.

The position of the resonance peak of the impedance sensor is determined by the size of the impedance sensor, so that different resonance peaks of the impedance sensor can be realized through the magnetic steels with different sizes.

Example 3:

on the basis of embodiment 1, this embodiment provides an engineering structure health monitoring device, engineering structure includes steel construction, bolt and pipeline.

When the method is used for detecting the thickness of a steel structure, the thickness is within the range of 2-5mm, and the frequency band range is 40-90kHz, so that impedance sensors of different resonance peaks within the detection frequency band range are connected in series, the detection range of impedance can be greatly widened, and the damage position can be quickly and accurately found.

And detecting the bolt load, wherein the frequency band ranges from 10 kHz to 100 kHz. By the same method, the looseness of the bolt can be quickly detected, and engineering accidents are avoided.

Example 4:

on the basis of embodiment 1, the present embodiment provides an engineering structure health monitoring device, and the piezoelectric ceramic is barium titanate, lead zirconate titanate, or lead magnesium niobate.

Piezoelectric ceramics mainly have three main categories: barium titanates (BaTiO)₃) The raw materials comprise titanium dioxide, barium carbonate, strontium carbonate and the like; lead zirconate titanate (PbZrTiO)₃) The raw materials include titanium dioxide, zirconium oxide, lead oxide, strontium carbonate, niobium oxide, lanthanum oxide, etc.; lead magnesium niobate (PbNbMgO)₃) The raw materials include niobium oxide, magnesium oxide, lead oxide, strontium carbonate and lanthanum oxide.

Both the material and the size have an influence on the position of the resonance peak, and therefore the material is also an important parameter to consider.

Example 5:

the embodiment provides an engineering structure health monitoring method, which comprises the following steps:

step 1) preparing a plurality of impedance sensors with different resonance peaks according to a monitored object to be connected in series to form an engineering structure health monitoring device;

step 2) installing the impedance sensor on the surface of the monitored object, connecting the anode and the cathode of the impedance sensor connected in series by using an impedance analyzer, applying sweep frequency excitation to carry out piezoelectric impedance measurement, wherein the sweep frequency range is consistent with the detection frequency band range of the monitored object;

and 3) when the resonance peak of one or more impedance sensors has frequency shift or peak value change, judging that the installation position of the impedance sensor has damage.

The principle of the method is as follows:

the piezoelectric ceramic of the impedance sensor and the tested structure can be coupled with each other, the mechanical impedance of the structure is coupled into the electrical impedance of the piezoelectric ceramic, and the change of the electrical impedance of the piezoelectric ceramic can indirectly reflect the change of the mechanical impedance of the structure caused by damage.

The method simultaneously obtains the impedance characteristics of each impedance sensor in the series impedance sensor array through one-time measurement, and provides a reliable method and technology for rapid impedance detection.

Example 6:

on the basis of embodiment 5, this embodiment provides an engineering structure health monitoring method, and the specific process of step 1) is as follows:

(1) selecting a detection frequency band range according to a monitored object, and determining a plurality of resonance peaks in the detection frequency band range;

such as: detecting the thickness of the steel structure, wherein the thickness is within the range of 2-5mm, and the frequency band range is 40-90 kHz; and detecting the bolt load, wherein the frequency band ranges from 10 kHz to 100 kHz.

(2) Establishing an impedance finite element calculation model, simulating the impedance characteristics of different sizes and different materials aiming at each resonance peak value, and selecting the size and the material with high responsiveness to prepare each impedance sensor;

(3) and connecting the impedance sensors in series through a lead and a binding clip.

The impedance characteristics of the impedance sensors with different sizes are simulated by using finite element numerical values, and the detection range of the impedance is greatly widened by serially combining the impedance sensors with different sizes.

The number of the impedance sensors is related to the required detection precision, for example, the detection range of the engineering structure is 30-70kHz, and the impedance sensors with 30kHz, 40 kHz, 50 kHz, 60 kHz and 70kHz 5 frequencies can be selected to be combined with consideration of the detection precision. The higher the detection accuracy requirement, the more the impedance sensor, the better under the condition of ensuring that the resonance peak is not seriously overlapped.

Example 7:

on the basis of embodiment 6, this embodiment provides an engineering structure health monitoring method, and the specific process of step (2) is as follows: the method comprises the steps that firstly, finite element software carries out geometric modeling on a monitored object according to the size and the material of the monitored object, then, grid division is carried out, then, impedance sensor modeling is carried out according to the size and the material of different impedance sensors, the impedance sensors are installed on the same position of the surface of the monitored object in a simulation mode, then, constraint and load are applied, finally, the impedance characteristics of different sizes and different materials are obtained through numerical simulation, and the size and the material with high responsiveness are selected to prepare each impedance sensor.

The finite element software may be ansys or comsol, and since the finite element is a numerical calculation, it must be discretized to perform the calculation, and there are various methods for mesh division, such as free mesh division, mapping mesh division, and sweep mesh division, and hybrid mesh division. For different geometric models, different meshing methods are used. The meshing belongs to the prior art, and the method only applies meshing to establish a finite element model and does not belong to an improvement point.

In this embodiment, taking detection of crossing pipes as an example, 1, geometric modeling: geometric modeling is carried out through ansys according to the inner diameter, the outer diameter and the material of the pipeline (shown in figure 1); 2. partitioning the grid (as shown in fig. 2); 3. modeling the impedance sensor according to the size and the material of the impedance sensor, and then applying a load (as shown in FIG. 3); 4. the result, i.e., the impedance sensor response plot (shown in fig. 4), is solved. Wherein, the square at the top of the pipeline in fig. 1, 2 and 3 is an impedance sensor.

Example 8:

on the basis of embodiment 6, this embodiment provides an engineering structure health monitoring method, after each impedance sensor is connected in series through a wire and a binding clip, an impedance analyzer is used to analyze the impedance characteristics of the impedance sensor, and the impedance characteristics are compared with the detection frequency band range in step (1), if each resonance peak is within the detection frequency band range, the preparation of the engineering structure health monitoring device is completed, and if a certain resonance peak or certain resonance peaks are not within the detection frequency band range, step (2) is repeated, and the size and the material are changed to optimize until each resonance peak is within the detection frequency band range.

The selected detection frequency band range of the embodiment is 30kHz-80kHz, and 4 resonance peaks are designed to appear in the range interval, wherein the resonance peaks are respectively 35kHz, 45kHz, 65kHz and 75 kHz. According to the method provided by the embodiment 7, the materials and the sizes corresponding to the 4 impedance sensors are obtained, the first impedance sensor1, the second impedance sensor2, the third impedance sensor3 and the fourth impedance sensor4 are obtained through processing, and the first impedance sensor, the second impedance sensor, the third impedance sensor and the fourth impedance sensor are connected in series through the lead 5 to form the engineering structure health monitoring device, as shown in fig. 5. Meanwhile, the impedance characteristics of the engineering structure health monitoring device are tested, and as shown in fig. 6, the device meets the design requirements.

Example 9:

in this embodiment, the structure of the bolt connection between two steel plates is used as the monitoring object, and the present invention is further described in detail.

The steel plate has the size of 1000mm multiplied by 182mm multiplied by 5mm, and is connected by 4 bolts, and the distance between the centers of two adjacent bolts is 255 mm. The 4 manufactured impedance sensors use the same piezoelectric ceramic pieces and magnetic steels with different thicknesses so as to obtain different impedance response resonance frequencies. For convenience, the 4 impedance sensors are respectively marked as Sensor1, Sensor2, Sensor3 and Sensor4, and the thicknesses of the used magnetic steels are 2mm, 3mm, 4mm and 5mm in sequence, and the diameters of the magnetic steels are 20 mm. The piezoelectric ceramic sheet used by the impedance sensor is lead zirconate titanate PZT5h, and the size is 10mm in length, 10mm in width and 0.5mm in thickness.

The manufactured 4 impedance sensors are attached to the outer side surfaces of the 4 bolt nuts and are connected in series, namely the positive electrode of one Sensor is connected with the negative electrode of the next Sensor, and a single-input multi-output system is formed. And (3) twisting 4 bolts to be fully tight by using a torque wrench, connecting the positive electrode and the negative electrode of the series impedance sensor by using an impedance analyzer, applying sweep frequency excitation to carry out piezoelectric impedance measurement, wherein the sweep frequency range is selected from 30kHz to 90kHz, and the step pitch is 50 Hz.

The measured data is transmitted via a cable connection to a PC for storage and analysis. Similarly, the disconnection clamp measures the impedance response of 4 impedance sensors individually, and compares the results of the individual impedance sensor measurements with the results of the series connection. As shown in fig. 7, the impedance response of the series connection has 4 resonance peaks (marked as P1, P2, P3 and P4), the peak frequency is 38 kHz (P1), 55 kHz (P2), 66.5kHz (P3) and 76.5 kHz (P4), and the peak amplitude is increased compared with that of a single Sensor. It can be found that P1, P2, P3 and P4 correspond to the resonant peak frequencies of Sensor1, Sensor2, Sensor3 and Sensor4, respectively (as seen from the separate measurements of the individual impedance sensors). The position where damage occurs can be judged by the mounting position of the impedance sensor.

Bolt tightness test experiment verification:

on the basis of full tightness of the bolts, the bolts at the Sensor1 are loosened, the states of other bolts are kept unchanged, the torque is reduced from 90 N.m to 60 N.m, 30 N.m and 0 N.m in sequence, 4 bolt pre-tightening conditions are totally adopted, the impedance response of the series piezoelectric Sensor is measured by an impedance analyzer, and the measurement result is shown in FIG. 8. It can be seen that as the pretightening force is reduced, the frequency of the impedance peak (P1) of the Sensor1 is shifted to the left because the local rigidity of the bolt at the Sensor1 is reduced due to the loosening of the bolt, and further the resonance frequency is reduced, and the larger the loosening degree is, the larger the damage is, and the lower the peak frequency is. And the other three bolts are not loosened, so that the frequencies corresponding to the resonance peaks (P2-P4) are almost unchanged.

The above examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention, which is intended to be covered by the claims and any design similar or equivalent to the scope of the invention.