CN106644226B - Friction resistance calibration device for liquid crystal coating - Google Patents
Friction resistance calibration device for liquid crystal coating Download PDFInfo
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- CN106644226B CN106644226B CN201710064984.3A CN201710064984A CN106644226B CN 106644226 B CN106644226 B CN 106644226B CN 201710064984 A CN201710064984 A CN 201710064984A CN 106644226 B CN106644226 B CN 106644226B
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- 239000004973 liquid crystal related substance Substances 0.000 title claims abstract description 39
- 239000011248 coating agent Substances 0.000 title claims abstract description 35
- 238000000576 coating method Methods 0.000 title claims abstract description 35
- 239000011521 glass Substances 0.000 claims abstract description 33
- 230000007246 mechanism Effects 0.000 claims abstract description 4
- 238000010008 shearing Methods 0.000 claims description 7
- 229910000737 Duralumin Inorganic materials 0.000 claims description 3
- 239000000463 material Substances 0.000 claims description 3
- 230000005540 biological transmission Effects 0.000 claims description 2
- 238000005259 measurement Methods 0.000 abstract description 5
- 238000012360 testing method Methods 0.000 abstract description 3
- 230000008859 change Effects 0.000 description 5
- 230000009471 action Effects 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 230000003068 static effect Effects 0.000 description 3
- 239000005304 optical glass Substances 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 1
- 238000011088 calibration curve Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
- G01L5/0028—Force sensors associated with force applying means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
- G01L5/0028—Force sensors associated with force applying means
- G01L5/0033—Force sensors associated with force applying means applying a pulling force
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Liquid Crystal (AREA)
Abstract
A friction resistance calibration device for a liquid crystal coating relates to the field of measurement of friction resistance of a model surface in a wind tunnel test; comprises a glass disc, an outer cover, a tray, a measuring table, a base, a fixed pulley and weights; wherein, the base is a disc mechanism and is horizontally arranged at the lowest end; the measuring table is vertically fixed on the upper surface of the base; the tray is fixedly arranged on the upper surface of the base; the glass plate is fixedly arranged on the upper surface of the tray; the outer cover is fixedly arranged on the upper surface of the tray; the outer edge of the glass disc is limited and fixed through an outer cover; the fixed pulley is fixedly arranged at the edge of the base; the weight is fixedly connected with the side edge of the outer cover through the inelastic rope, and the inelastic rope is placed on the fixed pulley; the invention can directly obtain the result without other sensors, the measurement result is not influenced by the precision of other sensors, the loading is easy to adjust and control, and the calibration precision is improved. The device has small volume, simple structure, high maintainability, economy and practicality.
Description
Technical Field
The invention relates to the field of measurement of model surface friction resistance in a wind tunnel test, in particular to a friction resistance calibration device for a liquid crystal coating.
Background
Under the high-speed flight environment, the proportion of friction resistance in the total resistance of the aircraft is large, the aerodynamic performance of the aircraft is influenced, and the aerodynamic heat is also greatly influenced. As a basic work of fluid mechanics, the research of friction prediction is emphasized by people, and research institutions and universities of countries all over the world put great strength into research of friction. Due to the influence of the flow state, particularly under the hypersonic speed condition, the flow is transited from the layer flow to the turbulent flow state, the prediction of the friction resistance has certain difficulty in both wind tunnel experiments and numerical simulation, and the root of the difficulty lies in the small absolute value of the friction resistance and the complexity of the flow.
In recent years, a technology for measuring friction resistance by using shear sensitive liquid crystal is gradually developed in China, but how to establish direct connection between the color change response of the liquid crystal and the absolute value of the friction force is a difficult point for restricting further development of the technology. The conventional calibration method usually depends on establishing a standard flow field and then performing comparison measurement by using other sensors, and the method is complex and difficult to control, introduces other errors and cannot well meet the requirement on test accuracy.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a friction resistance calibration device for a liquid crystal coating, which can directly obtain a result without using other sensors, the measurement result is not influenced by the precision of other sensors, the loading is easy to adjust and control, and the calibration precision is improved. The device has small volume, simple structure, high maintainability, economy and practicality.
The above purpose of the invention is realized by the following technical scheme:
a friction resistance calibration device for a liquid crystal coating comprises a glass disc, an outer cover, a tray, a measuring table, a base, a fixed pulley and a weight; wherein, the base is a disc mechanism and is horizontally arranged at the lowest end; the measuring table is vertically fixed on the upper surface of the base; the tray is fixedly arranged on the upper surface of the base; the glass plate is fixedly arranged on the upper surface of the tray; the outer cover is fixedly arranged on the upper surface of the tray; the outer edge of the glass disc is limited and fixed through an outer cover; the fixed pulley is fixedly arranged at the edge of the base; the weight is fixedly connected with the side edge of the outer cover through the inelastic rope, and the inelastic rope is placed on the fixed pulley.
In the above friction resistance calibration device for a liquid crystal coating, a through hole is arranged in the middle of the tray; the side measuring table is fixedly arranged at the central position of the base; the top end of the measuring table penetrates through the through hole of the tray to be in contact with the lower surface of the glass disc; the side measuring table, the tray and the glass tray are vertically and concentrically arranged.
In the above device for calibrating the frictional resistance of the liquid crystal coating, the diameter of the glass plate is 90-110 mm; the thickness is 8-12mm, and the light transmittance is more than 95%.
In the above calibration device for the frictional resistance of the liquid crystal coating, the measuring table has a cylindrical structure, and the diameter of the measuring table is 28-32 mm; the upper surface of the measuring table is coated with a liquid crystal coating, and the thickness of the liquid crystal coating is 20-30 mu m; and the measuring table material is duralumin.
In the above frictional resistance calibration device for the liquid crystal coating, the fixed pulley is arranged at a position which is equal to the outer cover in the vertical direction, so that the inelastic rope applies a horizontal shearing force to the outer edge of the outer cover under the weight of the weight.
In the above frictional resistance calibration device for the liquid crystal coating, the weight has a mass of 1-15 g.
In the frictional resistance calibration device for the liquid crystal coating, a white light source is fixedly arranged right above the center of the upper surface of the glass disc, and the color temperature of the white light source is 4900-5100K.
In the above frictional resistance calibration device for a liquid crystal coating, a camera is fixedly mounted above the upper surface of the glass plate.
In the above frictional resistance calibration device for the liquid crystal coating, the angle a between the camera and the normal of the central position of the glass disc is 30-60 degrees, and the camera is fixedly installed opposite to the fixed pulley.
Compared with the prior art, the invention has the following advantages:
(1) the invention adopts simple and direct static friction as loading input, is easier to obtain than gas jet flow, improves the economy, is easier to adjust the loading size and improves the calibration precision;
(2) the whole calibration device has small volume, simple structure and high maintainability;
(3) the loaded friction force can be obtained by calculation through a simple theoretical formula, the loaded friction force value is given without depending on other sensors, and negative effects on calibration accuracy caused by errors of other sensors are avoided.
Drawings
FIG. 1 is a top view of a calibration device according to the present invention;
fig. 2 is a front view of the calibration device of the present invention.
Detailed Description
The invention is described in further detail below with reference to the following figures and specific examples:
the static friction force is used as the standard input required by calibration, so that the response of the sensing element, namely the liquid crystal coating, to the friction force is observed, and the required calibration data is obtained. The liquid crystal coating is a material sensitive to shearing force, when the liquid crystal coating is subjected to shearing action, the wavelength of external reflected light of the liquid crystal can be changed, so that people can observe the color change of the liquid crystal, and the color change observed along the direction of the action of the shearing force is the largest. Therefore, a piece of glass can be placed on the surface of the object with the liquid crystal coating, the glass is in direct contact with the liquid crystal coating, a weight applies transverse tension (not more than the maximum static friction force) to the glass through a fixed pulley, the color change of the liquid crystal coating is observed and recorded at a certain pitch angle by a camera in the action direction of the transverse tension, and finally the corresponding relation between the color change and the loaded shearing force is calculated and calibrated.
As shown in fig. 1, which is a top view of the calibration device, it can be seen that the device for calibrating the frictional resistance of the liquid crystal coating comprises a glass plate 1, an outer cover 2, a tray 3, a measuring table 4, a base 5, a fixed pulley 6 and a weight 7; wherein, the base 5 is a disc mechanism, and the base 5 is horizontally arranged at the lowest end; the measuring table 4 is vertically fixed on the upper surface of the base 5; the tray 3 is fixedly arranged on the upper surface of the base 5; the glass disc 1 is fixedly arranged on the upper surface of the tray 3; the outer cover 2 is fixedly arranged on the upper surface of the tray 3; the outer edge of the glass disc 1 is limited and fixed through the outer cover 2; the fixed pulley 6 is fixedly arranged at the edge of the base 5; the weight 7 is fixedly connected with the side edge of the outer cover 2 through the inelastic rope, the inelastic rope is placed on the fixed pulley 6, and the weight 7 is 1-15g in mass.
Wherein the diameter of the glass disc 1 is 90-110 mm; the thickness is 8-12mm, and the light transmission rate is more than 95%.
The fixed pulley 6 is arranged at a position which is equal to the outer cover 2 in the vertical direction, so that the inelastic rope can apply horizontal shearing force to the outer edge of the outer cover 2 under the weight of the weight 7.
As shown in fig. 2, which is a front view of the calibration device, it can be seen that a through hole is provided in the middle of the tray 3; the side measuring table 4 is fixedly arranged at the central position of the base 5; the top end of the measuring table 4 passes through the through hole of the tray 3 to be contacted with the lower surface of the glass disc 1; the side measuring table 4, the tray 3 and the glass disc 1 are vertically and concentrically arranged.
The measuring table 4 is of a cylindrical structure, and the diameter of the measuring table is 28-32 mm; the upper surface of the measuring table 4 is coated with a liquid crystal coating, and the thickness of the liquid crystal coating is 20-30 mu m; and the measuring table 4 is made of duralumin.
A white light source 8 is fixedly arranged right above the center of the upper surface of the glass disc 1, and the color temperature of the white light source 8 is 4900-5100K.
A camera 9 is fixedly arranged above the upper surface of the glass disc 1; the angle a between the camera 9 and the normal line of the central position of the glass disc 1 is 30-60 degrees, and the camera 9 is fixedly arranged opposite to the fixed pulley 6.
A calibration process: and a shear sensitive liquid crystal coating is sprayed on the top surface of the side measuring table 4. After the liquid crystal coating is dried and stabilized, an optical glass disc 1 is placed on the top surface of the side measuring table 4, and the centers of the circles of the optical glass disc and the side measuring table are kept opposite. The whole device is placed in a darkroom, a white light source with approximate sunlight and a color temperature of about 5000K is adopted to directly illuminate the top surface of the side measuring table 4, and a camera 9 is arranged at the opposite side of the fixed pulley 6 for loading. The initial liquid crystal coating color was recorded by taking a picture first, then an equal weight was gradually added and the corresponding color was recorded. And finishing the loading after the loaded weight can cover the application target range. And importing the recorded digital image into a computer, and quantizing the obtained color by adopting an image processing technology to obtain a group of data for describing the color. A set of color data describing the magnitude of the friction was obtained. And fitting the two groups of data to obtain a final calibration curve.
Those skilled in the art will appreciate that those matters not described in detail in the present specification are well known in the art.
Claims (5)
1. The utility model provides a frictional resistance calibration device to liquid crystal coating which characterized in that: comprises a glass disc (1), an outer cover (2), a tray (3), a measuring table (4), a base (5), a fixed pulley (6) and weights (7); wherein, the base (5) is a disc mechanism, and the base (5) is horizontally arranged at the lowest end; the measuring table (4) is vertically fixed on the upper surface of the base (5); the tray (3) is fixedly arranged on the upper surface of the base (5); the glass plate (1) is fixedly arranged on the upper surface of the tray (3); the outer cover (2) is fixedly arranged on the upper surface of the tray (3); the outer edge of the glass disc (1) is limited and fixed through the outer cover (2); the fixed pulley (6) is fixedly arranged at the edge of the base (5); the weight (7) is fixedly connected with the side edge of the outer cover (2) through the inelastic rope, and the inelastic rope is placed on the fixed pulley (6);
a through hole is formed in the middle of the tray (3); the measuring table (4) is fixedly arranged at the central position of the base (5); the top end of the measuring table (4) passes through the through hole of the tray (3) to be contacted with the lower surface of the glass disc (1); the measuring table (4), the tray (3) and the glass disc (1) are vertically and concentrically arranged;
a white light source (8) is fixedly arranged right above the center of the upper surface of the glass disc (1), and the color temperature of the white light source (8) is 4900-5100K;
a camera (9) is fixedly arranged above the upper surface of the glass disc (1);
an included angle a between the camera (9) and the normal line of the center position of the glass disc (1) is 30-60 degrees, and the camera (9) is fixedly arranged opposite to the fixed pulley (6).
2. A device for calibrating frictional resistance of liquid crystal coating according to claim 1, wherein: the diameter of the glass disc (1) is 90-110 mm; the thickness is 8-12mm, and the light transmission rate is more than 95%.
3. A device for calibrating frictional resistance of liquid crystal coating according to claim 2, wherein: the measuring table (4) is of a cylindrical structure, and the diameter of the measuring table is 28-32 mm; the upper surface of the measuring table (4) is coated with a liquid crystal coating, and the thickness of the liquid crystal coating is 20-30 mu m; and the material of the measuring table (4) is duralumin.
4. A device for calibrating frictional resistance of liquid crystal coating according to claim 3, wherein: the fixed pulley (6) is arranged at a position which is equal to the outer cover (2) in height in the vertical direction, so that the non-elastic rope can apply horizontal shearing force to the outer edge of the outer cover (2) under the weight of the weight (7).
5. A device for calibrating the frictional resistance of a liquid crystal coating according to claim 4, wherein: the weight (7) has a mass of 1-15 g.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710064984.3A CN106644226B (en) | 2017-02-06 | 2017-02-06 | Friction resistance calibration device for liquid crystal coating |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710064984.3A CN106644226B (en) | 2017-02-06 | 2017-02-06 | Friction resistance calibration device for liquid crystal coating |
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| Publication Number | Publication Date |
|---|---|
| CN106644226A CN106644226A (en) | 2017-05-10 |
| CN106644226B true CN106644226B (en) | 2022-09-06 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201710064984.3A Active CN106644226B (en) | 2017-02-06 | 2017-02-06 | Friction resistance calibration device for liquid crystal coating |
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Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107607283B (en) * | 2017-07-24 | 2019-06-04 | 南京航空航天大学 | A kind of experimental rig and working method measuring plane overall situation friction force vector field |
| CN108225667B (en) * | 2017-12-28 | 2020-06-30 | 北京航空航天大学 | Pixel-level shear-sensitive liquid crystal calibration method and device |
| CN108240882A (en) * | 2017-12-28 | 2018-07-03 | 北京航空航天大学 | Pixel-level cuts quick liquid crystal calibration and measuring method and system |
| CN110672240B (en) * | 2019-10-23 | 2021-07-30 | 云南师范大学 | Static friction force measuring device based on optical fiber |
| CN113310611B (en) * | 2021-07-12 | 2023-08-18 | 中国兵器工业第五九研究所 | Nondestructive testing device and method for short-wavelength characteristic X-ray internal stress |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102393354A (en) * | 2011-10-20 | 2012-03-28 | 上海交通大学 | Intelligent soil engineering shear rheometer |
| CN103674479A (en) * | 2013-12-18 | 2014-03-26 | 哈尔滨工程大学 | Non-smooth surface fluid friction resistance testing device and testing method |
| CN106768822A (en) * | 2017-02-07 | 2017-05-31 | 中国航天空气动力技术研究院 | A kind of flow field boundary layer shear stress measuring method |
| CN206450354U (en) * | 2017-02-06 | 2017-08-29 | 中国航天空气动力技术研究院 | A kind of frictional resistance caliberating device for liquid crystal coatings |
-
2017
- 2017-02-06 CN CN201710064984.3A patent/CN106644226B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102393354A (en) * | 2011-10-20 | 2012-03-28 | 上海交通大学 | Intelligent soil engineering shear rheometer |
| CN103674479A (en) * | 2013-12-18 | 2014-03-26 | 哈尔滨工程大学 | Non-smooth surface fluid friction resistance testing device and testing method |
| CN206450354U (en) * | 2017-02-06 | 2017-08-29 | 中国航天空气动力技术研究院 | A kind of frictional resistance caliberating device for liquid crystal coatings |
| CN106768822A (en) * | 2017-02-07 | 2017-05-31 | 中国航天空气动力技术研究院 | A kind of flow field boundary layer shear stress measuring method |
Non-Patent Citations (1)
| Title |
|---|
| 《Measurement of Surface Shear Stress Vectors Using Liquid Crystal Coatings》;Daniel C.Reda et al.;《AIAA JOURNAL》;19940831;第32卷(第8期);第1576-1582页 * |
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