CN214503464U - Wood structure water content measuring device based on wave velocity method - Google Patents
Wood structure water content measuring device based on wave velocity method Download PDFInfo
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- CN214503464U CN214503464U CN202120847092.2U CN202120847092U CN214503464U CN 214503464 U CN214503464 U CN 214503464U CN 202120847092 U CN202120847092 U CN 202120847092U CN 214503464 U CN214503464 U CN 214503464U
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Abstract
The utility model discloses a timber structure moisture content measuring device based on wave speed method for timber structure to await measuring carries out the moisture content and measures, include: the device comprises a sensor, a driver and a signal transmitting and receiving device; the sensor and the driver are connected with the wood structure to be detected in a point contact mode; the sensor and the driver are both connected with the signal transmitting and receiving device; PZT modules are arranged in the sensor and the driver; the driver is used for transmitting an excitation signal to the wood structure to be tested and generating a stress wave in the wood structure to be tested; the sensor is used for receiving the stress wave and sending the stress wave to the signal transmitting and receiving device as a sensing signal; the signal transmitting and receiving device is used for simultaneously acquiring an excitation signal transmitted by the driver and a sensing signal transmitted by the sensor and acquiring the moisture content of the wood structure to be detected based on the excitation signal and the sensing signal. The utility model discloses can realize quick, convenient nondestructive test, be applicable to various types of timber compoments, have wide application prospect.
Description
Technical Field
The utility model relates to a wood working and timber structure building field especially relate to a timber structure moisture content measuring device based on wave speed method.
Background
The water content of the wood component is one of important parameters influencing the service performance and long-term service durability of the wood structure building. The mechanical properties, particularly the elastic modulus, of the wood member are significantly affected by the water content. In addition, in the long-term service process of the wood structure, the change of the water content can affect the creep property of the wood member, and termites and the like can be bred, so that holes and corrosion in the member are caused. Internal holes and corrosion weaken the cross section bearing capacity of the member, and bring about potential safety hazards to the structure.
At present, a drying method and a resistance method are mainly used for measuring the moisture content of a wood member in service. The drying method needs to sample the components, the moisture content is measured according to a standard method for measuring the moisture content, a constant temperature box, a vernier caliper and an electronic balance are used in the measuring process, and the moisture content is calculated according to the mass and volume changes of the wood component samples before and after drying. The method needs a long time, and the sample is generally placed in the constant temperature box for about 6 hours, so that the method is not suitable for quick detection of engineering application. The principle of resistance measurement is that the moisture content of wood and the resistance characteristic thereof present a certain relationship, and the moisture content of the wood component is obtained by substituting the resistance measured by the resistance meter into a relational expression of the moisture content and the resistance. The method is convenient to measure, but the range of the water content capable of being measured is limited, generally limited to about 5-30%, and the method is greatly influenced by wood tree species.
Therefore, it is especially necessary to provide a wood structure moisture content measuring device with fast and convenient nondestructive detection and wide application range.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing a timber structure moisture content measuring device based on wave speed method to solve the technical problem that exists among the prior art, the probe adopts the point type contact, can realize quick, convenient nondestructive test, is applicable to various types of timber compoments, has wide application prospect.
In order to achieve the above object, the utility model provides a following scheme: the utility model provides a timber structure moisture content measuring device based on wave speed method for timber structure to await measuring carries out the moisture content and measures, include: the device comprises a sensor, a driver and a signal transmitting and receiving device; the sensor and the driver are connected with the wood structure to be detected in a point contact mode; the sensor and the driver are both connected with the signal transmitting and receiving device; PZT modules are arranged in the sensor and the driver;
the driver is used for transmitting an excitation signal to the wood structure to be tested, so that the excitation signal generates stress waves in the wood structure to be tested;
the sensor is used for receiving stress waves generated in the wood structure to be detected and sending the received stress waves to the signal transmitting and receiving device as sensing signals;
the signal transmitting and receiving device is used for simultaneously acquiring an excitation signal transmitted by the driver and a sensing signal transmitted by the sensor and acquiring the moisture content of the wood structure to be detected based on the excitation signal and the sensing signal.
Preferably, the excitation signal employs a sine window function.
Preferably, the sensor and the driver both comprise a first protective body, a second protective body and a probe which are sequentially connected, the probe is in point contact connection with the wood structure to be tested, and the PZT module is arranged in the second protective body.
Preferably, the first protection body and the second protection body are cylindrical structures, the inner diameter of the first protection body is the same as the outer diameter of the second protection body, the first protection body is a sleeve with a thread on the inner wall, the second protection body is a sleeve with a thread on the outer wall, and the first protection body is connected with the second protection body through a thread; the probe is of a conical structure, and the vertex of the conical structure is in point contact connection with the wood structure to be detected.
Preferably, the PZT module comprises a PZT sheet, a magnet connecting layer is arranged at the bottom of the PZT sheet, and an amplifying and modulating circuit is fixedly connected to the surface of the PZT sheet; the PZT sheet is also connected with a lead, and the lead is respectively connected with the anode and the cathode of the PZT sheet; the second protective body is provided with a wire hole, and a wire passes through the wire hole and is connected with the signal transmitting and receiving device; the PZT module is connected to the second protective body through the magnet connection layer.
Preferably, an epoxy resin protector is arranged on the periphery of the PZT sheet.
The utility model discloses a following technological effect:
(1) the utility model discloses the sensor all is equipped with the PZT module with the driver inside, excitation signal produces the stress wave in the timber structure that awaits measuring through the inverse piezoelectric effect of the PZT module of driver inside, after the stress wave passed the cross section of timber structure that awaits measuring, by the positive piezoelectric effect of the PZT module of sensor inside by signal transmission and receiving arrangement collection, through excitation signal, sensing signal's time delay acquires the propagation wave velocity of stress wave in the timber structure that awaits measuring, and obtain the moisture content of timber structure that awaits measuring through the calibration curve of wave velocity and timber structure moisture content, quick, convenient nondestructive test has been realized, and can be applicable to various types of timber structure, wide application prospect has;
(2) the PZT module of the utility model is provided with the magnet connecting layer, is connected with the second protective body through magnetic force, and has the advantages of easy installation and detachable;
(3) the utility model discloses sensor, driver are conical structure, carry out the point type contact with the timber structure that awaits measuring and are connected, have the advantage of operating simply, nondestructive test.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a device for measuring the moisture content of a wood structure based on a wave velocity method;
fig. 2 is a schematic diagram of the structure of the driver/sensor of the present invention;
FIG. 3 is a schematic structural diagram of a PZT module according to the present invention;
fig. 4 is a schematic diagram of an excitation signal and a sensing signal in an embodiment of the present invention;
FIG. 5 is a schematic diagram of a calibration curve of the wave velocity and the moisture content of the wood structure in the embodiment of the present invention;
in the figure, 1 is an epoxy resin protector, 2 is a PZT sheet, 3 is a magnet connection layer, 4 is an amplification modulation circuit, 5 is a lead, 11 is a first protector, 12 is a second protector, 13 is a lead hole, 14 is a probe, 21 is a sensor, 22 is a signal transmitting and receiving device, 23 is a wood structure to be measured, and 24 is a driver.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
In order to make the above objects, features and advantages of the present invention more comprehensible, the present invention is described in detail with reference to the accompanying drawings and the detailed description.
Referring to fig. 1 to 3, the present embodiment provides a wood structure moisture content measuring device based on a wave velocity method, which is used for measuring the moisture content of a wood structure 23 to be measured, and specifically includes: a sensor 21, a driver 24, a signal transmitting and receiving device 22; the sensor 21 and the driver 24 are connected with the wood structure 23 to be detected in a point contact manner; the sensor 21 and the driver 24 are both electrically connected to the signal transmitting and receiving device 22.
A PZT (Piezoelectric Transducer 21) module is disposed inside each of the sensor 21 and the driver 24.
The driver 24 is configured to transmit an excitation signal to the wood structure 23 to be tested, so that the excitation signal generates a stress wave in the wood structure 23 to be tested; wherein the excitation signal adopts a sine window function.
The sensor 21 is configured to receive a stress wave generated in the wood structure 23 to be measured, and send the received stress wave to the signal transmitting and receiving device 22 as a sensing signal;
the signal transmitting and receiving device 22 is configured to simultaneously acquire an excitation signal transmitted by the driver 24 and a sensing signal transmitted by the sensor 21, perform cross-correlation calculation on the two time-series discrete signals of the excitation signal and the sensing signal to obtain a time delay Δ t, measure a distance L between the driver 24 and the sensor 21, calculate a wave velocity v of the stress wave transmitted in the wood structure 23 to be measured according to a formula L/. DELTA.t, and calculate the water content of the wood structure 23 to be measured according to a calibration curve of the wave velocity v and the water content of the wood structure.
The sensor 21 and the driver 24 respectively comprise a first protective body 11, a second protective body 12 and a probe 14 which are connected in sequence; the first protective body 11 and the second protective body 12 are cylindrical structures, the inner diameter of the first protective body 11 is the same as the outer diameter of the second protective body 12, the first protective body 11 is a thin-walled sleeve with threads arranged inside, the second protective body 12 is a thin-walled sleeve with threads arranged outside, and the first protective body 11 is connected with the second protective body 12 through the threads; the probe 14 is in a conical structure, the vertex of the conical structure is in point contact connection with the wood structure 23 to be detected, the operation is simple, and the nondestructive detection of the wood structure 23 to be detected can be realized; the PZT module is disposed in the second protective body 12, and the inner diameter of the second protective body 12 is the same as the inner diameter of the PZT module; the first protector 11 is equivalent to the cover of the second protector 12, and the first protector and the second protector are connected by threads, so that the internal PZT module can be conveniently detached and replaced.
The PZT module comprises a PZT sheet 2, the PZT sheet 2 is a main sensing element, an epoxy resin protector 1 is arranged on the periphery of the PZT sheet 2, and the sensing material can be protected from being influenced and damaged by the environment through the epoxy resin protector 1, so that the service lives of the sensor and the driver are prolonged; the bottom of the PZT sheet 2 is provided with a magnet connecting layer 3, the surface of the PZT sheet 2 is fixedly connected with an amplifying and modulating circuit 4, and the amplifying and modulating circuit 4 is welded on the surface of the PZT sheet 2; the PZT sheet 2 is also connected with a lead 5, and the lead 5 is respectively connected with the anode and the cathode of the PZT sheet 2; the second protective body 12 is provided with a wire hole 13, and the wire 5 passes through the wire hole 13 and is connected with the signal transmitting and receiving device 22; the PZT module is connected with the second protective body 12 through the magnet connecting layer 3, and has the advantages of easy installation and detachability through a magnetic force connection mode.
The utility model discloses timber structure moisture content measuring device based on wave velocity method's work flow as follows:
the sensor 21 and the driver 24 are respectively connected with the signal transmitting and receiving device 22 through a lead 5, and the sensor 21 and the driver 24 are connected with the wood structure 23 to be measured in a point contact mode;
an excitation signal is transmitted to the wood structure 23 to be detected through the driver 24, a stress wave generated in the wood structure 23 to be detected by the excitation signal is received through the sensor 21, and the stress wave is used as a sensing signal and is sent to the signal transmitting and receiving device 22;
wherein, the excitation signal transmitted by the driver 24 to the wood structure 23 to be measured is a sine window function, the sine window function is generated in matlab, and the period, the frequency and the number of sampling points are set in matlab to generate the sine window function; the frequency of the sine window function is the natural vibration frequency of the PZT sheet 2, the sine window function is a column of amplitude data generated in matlab, and the amplitude data is stored as a text file type. Selecting the excitation signal type as 'self-defined waveform' on the control panel of the signal transmitting and receiving device 22, introducing the modulated sine window function file, and transmitting and receiving the signalSetting 22 emission time interval, amplitude increasing coefficient and sampling frequency fsAnd sends a sine window function wave excitation signal to the wood structure 23 to be measured through the driver 24.
The excitation signal generates a stress wave in the wood structure 23 to be measured through the inverse piezoelectric effect of the PZT module inside the driver 24, and after the stress wave passes through the cross section of the wood structure 23 to be measured, the stress wave is collected by the signal transmitting and receiving device 22 through the positive piezoelectric effect of the PZT module inside the sensor 21, as shown in fig. 4, T is an excitation signal, and R1 is a sensing signal.
Performing cross-correlation calculation on the excitation signals and the sensing signals through the signal transmitting and receiving device 22 to obtain time delay between the excitation signals and the sensing signals, and calculating the wave velocity of the stress wave transmitted in the wood structure 23 to be measured based on the time delay and the distance between the driver 24 and the sensor 21;
due to the existence of the time delay between the excitation signal and the sensing signal, the time delay Δ t between the two time-series discrete signals of the excitation signal and the sensing signal is calculated through a cross-correlation function, the distance L between the driver 24 and the sensor 21 is measured at the same time, and the wave velocity v of the stress wave transmitted in the wood structure 23 to be measured is calculated based on the time delay Δ t and the distance L between the driver 24 and the sensor 21, as shown in the following formula:
wherein the cross-correlation function is represented by:
wherein, x (m) is an excitation signal, y (m + N) is a sensing signal, and N is the number of discrete data points of the sensing signal; r (n) is a correlation coefficient vector, the maximum value of the vector is denoted as max (r), and the time delay Δ t between the excitation signal and the sensing signal is calculated according to the following formula:
where Index is max (R) Index position in time series, N is the number of discrete data points of the sensing signal, fsIs the sampling frequency of the excitation signal, fsProvided in the control panel of the signal transmitting and receiving device 22.
And acquiring a calibration curve of the wave velocity and the water content of the wood structure, and obtaining the water content of the wood structure 23 to be detected based on the calibration curve and the wave velocity of the stress wave transmitted in the wood structure 23 to be detected. The method for acquiring the calibration curve of the wave velocity and the water content of the wood structure comprises the following steps:
selecting wood structures of different types and different water contents, calibrating the water contents, and measuring the wave velocity to obtain a calibration curve of the wave velocity and the water contents of the wood structures, as shown in FIG. 5; through the calibration curve of moisture content, can carry out quick, convenient, nondestructive test through the wave speed to the moisture content of timber structure 23 that awaits measuring, and be applicable to various types of timber structure.
The utility model discloses following technological effect has:
(1) the utility model discloses the sensor all is equipped with the PZT module with the driver inside, excitation signal produces the stress wave in the timber structure that awaits measuring through the inverse piezoelectric effect of the PZT module of driver inside, after the stress wave passed the cross section of timber structure that awaits measuring, by the positive piezoelectric effect of the PZT module of sensor inside by signal transmission and receiving arrangement collection, through excitation signal, sensing signal's time delay acquires the propagation wave velocity of stress wave in the timber structure that awaits measuring, and obtain the moisture content of timber structure that awaits measuring through the calibration curve of wave velocity and timber structure moisture content, quick, convenient nondestructive test has been realized, and can be applicable to various types of timber structure, wide application prospect has;
(2) the PZT module of the utility model is provided with the magnet connecting layer, is connected with the second protective body through magnetic force, and has the advantages of easy installation and detachable;
(3) the utility model discloses sensor, driver are conical structure, carry out the point type contact with the timber structure that awaits measuring and are connected, have the advantage of operating simply, nondestructive test.
The above-mentioned embodiments are only intended to describe the preferred embodiments of the present invention, but not to limit the scope of the present invention, and those skilled in the art should also be able to make various modifications and improvements to the technical solution of the present invention without departing from the spirit of the present invention, and all such modifications and improvements are intended to fall within the scope of the present invention as defined in the appended claims.
Claims (6)
1. The utility model provides a timber structure moisture content measuring device based on wave velocity method for carry out the moisture content to timber structure (23) that awaits measuring and measure, its characterized in that includes: a sensor (21), a driver (24), a signal transmitting and receiving device (22); the sensor (21) and the driver (24) are connected with the wood structure (23) to be detected in a point contact mode; the sensor (21) and the driver (24) are both connected with the signal transmitting and receiving device (22); PZT modules are arranged in the sensor (21) and the driver (24);
the driver (24) is used for transmitting an excitation signal to the wood structure (23) to be tested, so that the excitation signal generates a stress wave in the wood structure (23) to be tested;
the sensor (21) is used for receiving stress waves generated in the wood structure (23) to be detected and sending the received stress waves serving as sensing signals to the signal transmitting and receiving device (22);
the signal transmitting and receiving device (22) is used for simultaneously acquiring an excitation signal transmitted by the driver (24) and a sensing signal transmitted by the sensor (21), and acquiring the water content of the wood structure (23) to be detected based on the excitation signal and the sensing signal.
2. The device for measuring the moisture content of the wood structure based on the wave velocity method according to claim 1, wherein the excitation signal adopts a sine window function.
3. The device for measuring the water content of the wood structure based on the wave velocity method is characterized in that the sensor (21) and the driver (24) respectively comprise a first protective body (11), a second protective body (12) and a probe (14) which are sequentially connected, the probe (14) is in point contact connection with the wood structure (23) to be measured, and the PZT module is arranged in the second protective body (12).
4. The wave velocity method-based wood structure water content measuring device according to claim 3, wherein the first protective body (11) and the second protective body (12) are cylindrical structures, the inner diameter of the first protective body (11) is the same as the outer diameter of the second protective body (12), the first protective body (11) is a sleeve with threads on the inner wall, the second protective body (12) is a sleeve with threads on the outer wall, and the first protective body (11) and the second protective body (12) are connected through threads; the probe (14) is of a conical structure, and the vertex of the conical structure is in point contact connection with the wood structure (23) to be detected.
5. The device for measuring the moisture content of the wood structure based on the wave velocity method is characterized in that the PZT module comprises a PZT sheet (2), a magnet connecting layer (3) is arranged at the bottom of the PZT sheet (2), and an amplification and modulation circuit (4) is fixedly connected to the surface of the PZT sheet (2); the PZT sheet (2) is also connected with a lead (5), and the lead (5) is respectively connected with the anode and the cathode of the PZT sheet (2); the second protective body (12) is provided with a wire hole (13), and the wire (5) penetrates through the wire hole (13) to be connected with the signal transmitting and receiving device (22); the PZT module is connected to the second protective body (12) via the magnet connection layer (3).
6. The device for measuring the water content of the wood structure based on the wave velocity method according to claim 5, wherein an epoxy resin protector (1) is arranged on the periphery of the PZT sheet (2).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120847092.2U CN214503464U (en) | 2021-04-23 | 2021-04-23 | Wood structure water content measuring device based on wave velocity method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120847092.2U CN214503464U (en) | 2021-04-23 | 2021-04-23 | Wood structure water content measuring device based on wave velocity method |
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| CN214503464U true CN214503464U (en) | 2021-10-26 |
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| CN202120847092.2U Active CN214503464U (en) | 2021-04-23 | 2021-04-23 | Wood structure water content measuring device based on wave velocity method |
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- 2021-04-23 CN CN202120847092.2U patent/CN214503464U/en active Active
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