CN203672525U - Concrete stress sensor using piezoelectric characteristic of PVDF film - Google Patents
Concrete stress sensor using piezoelectric characteristic of PVDF film Download PDFInfo
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- CN203672525U CN203672525U CN201320850021.3U CN201320850021U CN203672525U CN 203672525 U CN203672525 U CN 203672525U CN 201320850021 U CN201320850021 U CN 201320850021U CN 203672525 U CN203672525 U CN 203672525U
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Abstract
The utility model discloses a concrete stress sensor using a piezoelectric characteristic of a PVDF (polyvinylidene fluoride) film. The concrete stress sensor comprises a sensor housing and a PVDF piezoelectric film, wherein the sensor housing is formed by buckling a top housing and a bottom housing and the PVDF piezoelectric film is arranged between the top housing and the bottom housing. A nylon sleeve sleeves the periphery of the PVDF piezoelectric film in order to fix the PVDF piezoelectric film to a boss. An insulating layer is disposed on the top end face of the PVDF piezoelectric film and tightly contacts the top sensor housing. Another insulating layer is disposed on the bottom end face of the PVDF piezoelectric film and tightly contacts the bottom sensor housing. An enclosed insulating space is formed by the nylon sleeve and the insulating layers and separates the PVDF piezoelectric film from the sensor housing in an insulating manner. The top surface and the bottom surface of the PVDF piezoelectric film are equipped with wiring electrodes which transmit electric signals to a unit outside the sensor. The PVDF piezoelectric film is clamped between the two metallic housings and load is transmitted to the PVDF piezoelectric film through the metallic sensor housing, thereby achieving sensitive sensing. The concrete stress sensor is simple in structure, easy to package, small in size, and capable of being pre-embedded in concrete material to complete an impact stress test.
Description
Technical field
The utility model relates to a kind of strain gauge, for measuring the strain gauge of Concrete Under Impact Load material stress, be specifically related to a kind of concrete stress sensor that utilizes organic piezoelectric materials, particularly one is utilized PVDF(segregation fluorothene) the concrete stress sensor of film piezo-electric characteristic, belong to stress measurement technical field.
Background technology
At present, the sensor that is applied to shock-testing field is mainly divided into pressure resistance type and piezoelectric type two classes.
Up to now, people have found the multiple material that can be used as piezoresistance sensor, as copper-manganese, carbon, calcium, lithium, indium, lead, cadmium, bismuth and ytterbium etc., wherein modal pressure resistance type strain gauge is manganese-copper piezoresistance meter, although the piezoresistance coefficient of manganin, be that sensitivity is not very high, but because it has the features such as temperature-coefficient of electrical resistance is little, response is fast, the linearity is better, be applicable to very much and make UHV (ultra-high voltage) stress (power) sensor, up to the present, manganese-copper piezoresistance meter remains the pressure transducer that range is the highest, and the test upper limit can reach 100GPa.
And the conventional sensitive element of piezoelectric sensor mainly contains the segregation fluorothene (PVDF) that quartz, piezoelectric ceramics and development in recent years are got up.Quartz is the piezoelectric the most extensively adopting, if being 3ns(, the response time of piezoelectric signal has amplifier for 10ns), be 0.4 μ s typical writing time, such sensor is elastic strain district below 2.5GPa, the linearity is good, and precision can reach ± and 3%, but in the time that 2.5GPa is above, non-linear enhancing, precision obviously declines.The piezoelectric constant of piezoelectric ceramics is more much bigger than quartz, but because the physical strength of piezoelectric ceramics is little, Curie point is low, can only be applied under low pressure conditions and apply.
The shock-testing field that the sensor is applied in concrete material exists following deficiency separately.
For the manganese-copper piezoresistance meter of pressure resistance type, in the time of test, need the external corresponding pulse power and flip flop equipment, trouble comparatively in test, and be applied in low stress impact when test (maximum impact stress is no more than 100MPa), the measuring accuracy of manganese-copper piezoresistance meter can not meet test request.
For the quartz crystal sensor of piezoelectric type, generally can only test the shock wave section on test specimen surface, obtain test specimen internal stress by conversion, limit its range of application
For piezoelectric ceramics, because the physical strength of piezoelectric ceramics is little, under higher shock stress level, can go to sticks and staves, in the time measuring, need charge amplifier simultaneously, structure is more complicated, and the stress that cannot be applied to test specimen inside detects.
Utility model content
Technical problem to be solved in the utility model is to provide a kind of for measuring concrete material in the time experiencing a shock load action, can obtain the piezoelectric type strain gauge of the stress distribution of material internal, thereby solve existing sensor and can not effectively catch concrete material in the time experiencing a shock load action, the problem of the stress time-histories at material internal measuring point place.
The utility model utilizes PVDF(segregation fluorothene) piezoelectric property of film realizes above-mentioned purpose, concrete technical scheme is as follows: a kind of concrete stress sensor that utilizes PVDF film piezo-electric characteristic, comprise, sensor outer housing together of lower two parts spiral-lock and be arranged on the PVDF piezoelectric membrane between two parts sensor outer housing, wherein lower sensor shell inner central section position is provided with boss, described PVDF piezoelectric layer is arranged on described boss, center, the inner side corresponding position of described upper sensor shell is provided with groove and clip is contained on the lower sensor shell that is provided with boss, on described, between lower two parts sensor outer housing, be provided with flexible gaskets, described flexible gaskets provides a small axial displacement stroke to sensor internal, guarantee that external loads can effectively act on PVDF piezoelectric membrane, guarantee measuring accuracy and there is certain water resistance, described PVDF piezoelectric membrane peripheral sleeve is equipped with nylon sleeve PVDF piezoelectric membrane is positioned on described boss, the upper/lower terminal face of described PVDF piezoelectric layer arranges respectively close contact between insulation course and upper and lower two parts sensor outer housing, and described nylon sleeve and insulation course form the insulating space of sealing PVDF piezoelectric membrane and sensor outer housing insulation are separated, the upper and lower surface of described PVDF piezoelectric membrane arranges respectively link electrode piezoelectric signal is led to outside sensor.
Wherein, establish reeded upper sensor shell and be provided with at described groove periphery the ring recess of positioning nylon sleeve, two described flexible gaskets are separately positioned on described nylon sleeve two ends and upper and lower two parts sensor outer housing close contact.
In the utility model, described concrete stress sensor also comprises lead-out terminal, described lead-out terminal one end is electrically connected with the link electrode of described PVDF piezoelectric membrane upper and lower surface through described sensor outer housing and nylon sleeve, and the other end leads to outside sensor outer housing.
The thickness of described PVDF piezoelectric membrane is the circular membrane of 25～100 microns, and the upper and lower surface silver-plated processing respectively of described PVDF piezoelectric membrane.
As preferred version of the present utility model, described insulation course employing thickness is the polyimide film of 25～100 microns.
The thickness of described nylon sleeve is 1～5 millimeter.
In the utility model, described upper and lower two parts sensor outer housing is metal shell, and is connected by screw between described upper and lower two parts sensor outer housing, guarantee external loads can useful effect on PVDF piezoelectric membrane.
Because concrete stress sensor is normally cast in concrete sample, be provided with flexible water O-ring seal in the outer ring, junction of described upper and lower two parts sensor outer housing.
The utlity model has following beneficial effect:
1) PVDF piezoelectric membrane piezoelectric modulus is high, in the face of under identical stress level effect, higher more than 10 times than piezoelectric ceramics output intensity; Adopt the sensor that PVDF piezoelectric membrane is sensitive element to have splendid signal to noise ratio (S/N ratio), making can not need noise filtering in actual measurement; This piezoelectric membrane has the response speed of nanosecond, the wide cut pressure measurement scope of 0～20GPa, is applicable to being very much applied to the application of high voltage transient, such as the stress test under blast and percussive action; And PVDF has splendid pliability, can be processed into easily various shapes and thickness, physical strength is high, good endurance, quality is light, with low cost, reusable.
2) the utility model is clipped in PVDF piezoelectric membrane between two parts sheet metal shell, by sensor metal shell, load is passed to PVDF film, and sensing is sensitive, sensor construction is simple, encapsulation is convenient, and volume is little, can be embedded in and in concrete material, complete shock stress test.
3) the utility model adopts upper and lower two parts metal shell by PVDF piezoelectric membrane spiral-lock therein, adopt nylon sleeve and insulation course to form the electromagnetic screen space of sealing insulation, sensor outer housing is connected with the screen layer of twin-core shielded conductor by lead-out terminal and ground connection, test signal is not subject to the interference of electromagnetic environment, guarantees measuring accuracy; Adopt the packaging technology of spiral-lock, and the use of flexible water O-ring seal and flexible gaskets, guaranteed water resistance and the endurance quality of sensor, guaranteed in actual applications the stability of test result and consistance.
Below in conjunction with the drawings and specific embodiments, the utility model is described further.
Accompanying drawing explanation
Fig. 1 is the schematic appearance of the concrete stress sensor that relates to of the utility model.
Fig. 2 is the upward view of the concrete stress sensor that relates to of the utility model.
Fig. 3 is the P-P cut-open view in Fig. 2.
Fig. 4 is the upper and lower two parts sensor outer housing junction structural representation in Fig. 3.
Fig. 5 is the Q-Q cut-open view in Fig. 2.
Fig. 6 is the decomposing schematic representation of each parts of concrete stress sensor of relating to of the utility model.
Fig. 7 is the mimic channel figure of the concrete stress sensor that relates to of the utility model.
Number in the figure: 01, sensor outer housing the first half, 02, sensor outer housing the latter half, 03, insulation course, 04, PVDF piezoelectric membrane, 05, nylon sleeve, 06, flexible gaskets, 07, flexible water O-ring seal, 08, screw hole, 09, screw, 10, lead-out terminal, 11, link electrode.
Embodiment
Embodiment
Referring to Fig. 1 to Fig. 6, concrete stress sensor in diagram utilizes PVDF(segregation fluorothene) piezoelectric property of film, it comprises the sensitive element of the silver-plated PVDF piezoelectric membrane 04 in two sides as sensor, for the protection of sensitive element and the impact load in concrete material is passed to the metal sensor shell of sensitive element, for the lead-out terminal 10 being connected with test circuit, for the insulation course 03 and the nylon sleeve 05 that insulate between PVDF piezoelectric membrane 04 and sensor outer housing, for flexible gaskets 06 and the flexible water O-ring seal 07 of waterproof and sealing, the link electrode 11 being electrically connected with lead-out terminal 10 for PVDF piezoelectric membrane 04, for encapsulating the screw 09 of fixation of sensor shell.
Specifically referring to Fig. 3 to Fig. 6, the concrete structure of above-mentioned concrete stress sensor is as follows: sensor outer housing is cylindrical, by upper, lower two parts spiral-lock is at composition, wherein sensor outer housing the latter half 02 is provided with boss, described PVDF piezoelectric membrane 04 is arranged on described boss, sensor outer housing the first half 01 is provided with groove and clip is contained in the sensor outer housing the latter half that is provided with boss, on described, between lower two parts sensor outer housing, be provided with flexible gaskets 06, described flexible gaskets 06 provides a small axial displacement stroke to sensor internal, guarantee that external loads can effectively act on PVDF piezoelectric membrane, avoid part to be offset by two parts sensor outer housing, guarantee the measuring accuracy of sensor and there is certain water resistance, described PVDF piezoelectric layer 04 peripheral sleeve is equipped with nylon sleeve 05 and PVDF piezoelectric layer is positioned on the boss of sensor outer housing the latter half 02, the upper and lower faces of described PVDF piezoelectric membrane 04 arranges respectively close contact between insulation course 03 and upper and lower two parts sensor outer housing, and described nylon sleeve 05 is separated PVDF piezoelectric membrane 04 and sensor outer housing insulation with the insulating space that insulation course 03 forms sealing, the upper and lower faces of described PVDF piezoelectric membrane 04 arranges respectively link electrode 11 piezoelectric signal is led to outside sensor.
Further, the groove periphery in sensor outer housing the first half 01 is provided with the ring recess of positioning nylon sleeve 05, and two described flexible gaskets 06 are separately positioned on two ends and upper and lower two parts sensor outer housing close contact of described nylon sleeve 05.
Lead-out terminal 10 one end of sensor are electrically connected with the link electrode 11 of described PVDF piezoelectric membrane 04 upper and lower surface through described sensor outer housing and nylon sleeve, and the other end leads to outside sensor outer housing.Described nylon sleeve 05 and steel sensor outer housing have circular interior wiring hole at the medium position of short transverse, for the link electrode of PVDF piezoelectric membrane and being connected of lead-out terminal, this sensor can be connected with test circuit by twin-core shielded conductor in external circuit, sensor outer housing is connected with conductor shielding layer by lead-out terminal, guarantees to provide reliable electric property and electromagnetic screen.
It is the film of 25-100 micron that described PVDF piezoelectric membrane 04 adopts the thickness that existing market length is commonly used, and cuts into circle, and the upper and lower end face silver-plated processing respectively of described PVDF piezoelectric membrane.
As preferred version of the present utility model, it is the polyimide film of 20-50 micron that described insulation course 03 adopts thickness.Insulated and compressed by Kapton and PVDF piezoelectric membrane in steel shell inside, the stress in test specimen is passed on PVDF piezoelectric membrane by steel shell, simultaneously also for sensor internal assembly provides protection, and waterproof and electromagnetic screen.
The thickness of described nylon sleeve 05 is 2 millimeters, and described nylon ring is thin wall cylinder-shaped, is arranged in steel shell, radially wraps up PVDF piezoelectric membrane and Kapton, prevents that sensor internal element and shell are short-circuited.
In the utility model, described upper and lower two parts sensor outer housing is metal shell, and on described upper and lower two parts sensor outer housing, screw hole 08 is set, wherein in sensor outer housing the first half 01 for establishing female threaded hole, in sensor the latter half 02 is ladder hole, and the upper and lower two parts of sensor outer housing are by screw 09 encapsulation that is connected.
In the time of test, concrete stress sensor is normally cast in concrete sample and tests shock stress, is therefore also provided with flexible water O-ring seal 07 in the outer ring, junction of described upper and lower two parts sensor outer housing.For the basis guaranteeing water resistance, can provide a small axial displacement stroke to sensor internal as flexible gaskets 06 equally, guarantee that external loads can effectively act on PVDF piezoelectric membrane.
Specifically referring to Fig. 7, in actual application, PVDF piezoelectric sensor is done the used time by the impact load, can be considered the voltage source of the electric capacity of connecting, wherein voltage source V
srepresent PVDF film, the stress that its output valve and sensor stand be varied to direct ratio; And the electric capacity c of PVDF film
0can be considered as an equivalent capacitive reactance, when measurement and discharge resistance R form bleeder circuit.But c
0with the same RC oscillatory circuit that forms a single order of R, can be considered as a Hi-pass filter, filter out the low-frequency noise producing because of impact shock, farthest reduce the interference in output signal.
Claims (10)
1. one kind is utilized the concrete stress sensor of PVDF film piezo-electric characteristic, it is characterized in that: comprise sensor outer housing together of upper and lower two parts spiral-lock and be arranged on the PVDF piezoelectric membrane between two parts sensor outer housing, wherein, lower sensor shell inner central section position is provided with boss, described PVDF piezoelectric membrane is arranged on described boss, inside upper sensor shell, center corresponding position is provided with groove and clip is contained on the lower sensor shell that is provided with boss, between described upper and lower two parts sensor outer housing, is provided with flexible gaskets;
Described PVDF piezoelectric membrane peripheral sleeve is equipped with nylon sleeve PVDF piezoelectric membrane is positioned between described boss, the upper and lower surface of described PVDF piezoelectric membrane arranges respectively close contact between insulation course and upper and lower two parts sensor outer housing, and described nylon sleeve and insulation course form the insulating space of sealing PVDF piezoelectric membrane and sensor outer housing insulation are separated;
Upper and lower two surfaces of described PVDF piezoelectric membrane arrange respectively link electrode piezoelectric signal are led to outside sensor.
2. a kind of concrete stress sensor that utilizes PVDF film piezo-electric characteristic according to claim 1, it is characterized in that: establish reeded sensor outer housing and be provided with at described groove periphery the ring recess of positioning nylon sleeve, two described flexible gaskets are separately positioned on described nylon sleeve two ends and upper and lower two parts sensor outer housing close contact.
3. a kind of concrete stress sensor that utilizes PVDF film piezo-electric characteristic according to claim 1, it is characterized in that: described concrete stress sensor also comprises lead-out terminal, described lead-out terminal one end is electrically connected with the link electrode of the upper and lower both ends of the surface of described PVDF piezoelectric layer through described sensor outer housing and nylon sleeve, and the other end leads to outside sensor outer housing.
4. a kind of concrete stress sensor that utilizes PVDF film piezo-electric characteristic according to claim 1, is characterized in that: the thickness of described PVDF piezoelectric membrane is the circular membrane of 25～100 microns.
5. a kind of concrete stress sensor that utilizes PVDF film piezo-electric characteristic according to claim 4, is characterized in that: the upper and lower surface silver-plated processing respectively of described PVDF piezoelectric membrane.
6. a kind of concrete stress sensor that utilizes PVDF film piezo-electric characteristic according to claim 1, is characterized in that: described insulation course employing thickness is the Kapton of 25～100 microns.
7. a kind of concrete stress sensor that utilizes PVDF film piezo-electric characteristic according to claim 1, is characterized in that: the wall thickness of described nylon sleeve is 1～5 millimeter.
8. a kind of concrete stress sensor that utilizes PVDF film piezo-electric characteristic according to claim 1, is characterized in that: described upper and lower two parts sensor outer housing is metal shell.
9. a kind of concrete stress sensor that utilizes PVDF film piezo-electric characteristic according to claim 8, is characterized in that: between described upper and lower two parts sensor outer housing, be connected by screw and be connected.
10. a kind of concrete stress sensor that utilizes PVDF film piezo-electric characteristic according to claim 1, is characterized in that: the outer ring, junction of described upper and lower two parts sensor outer housing is provided with flexible water O-ring seal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320850021.3U CN203672525U (en) | 2013-12-20 | 2013-12-20 | Concrete stress sensor using piezoelectric characteristic of PVDF film |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320850021.3U CN203672525U (en) | 2013-12-20 | 2013-12-20 | Concrete stress sensor using piezoelectric characteristic of PVDF film |
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| Publication Number | Publication Date |
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| CN203672525U true CN203672525U (en) | 2014-06-25 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201320850021.3U Withdrawn - After Issue CN203672525U (en) | 2013-12-20 | 2013-12-20 | Concrete stress sensor using piezoelectric characteristic of PVDF film |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103674353A (en) * | 2013-12-20 | 2014-03-26 | 中南大学 | Concrete stress sensor by piezoelectric properties of PVDF (polyvinylidene fluoride) film |
| CN104155041A (en) * | 2014-07-28 | 2014-11-19 | 复旦大学 | Wireless passive prestress detection system |
-
2013
- 2013-12-20 CN CN201320850021.3U patent/CN203672525U/en not_active Withdrawn - After Issue
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103674353A (en) * | 2013-12-20 | 2014-03-26 | 中南大学 | Concrete stress sensor by piezoelectric properties of PVDF (polyvinylidene fluoride) film |
| CN103674353B (en) * | 2013-12-20 | 2015-07-15 | 中南大学 | Concrete stress sensor by piezoelectric properties of PVDF (polyvinylidene fluoride) film |
| CN104155041A (en) * | 2014-07-28 | 2014-11-19 | 复旦大学 | Wireless passive prestress detection system |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20140625 Effective date of abandoning: 20150715 |
|
| RGAV | Abandon patent right to avoid regrant |