CN114112345A - Rotating machinery blade strength analysis method based on photoelastic method - Google Patents
Rotating machinery blade strength analysis method based on photoelastic method Download PDFInfo
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- CN114112345A CN114112345A CN202111349162.2A CN202111349162A CN114112345A CN 114112345 A CN114112345 A CN 114112345A CN 202111349162 A CN202111349162 A CN 202111349162A CN 114112345 A CN114112345 A CN 114112345A
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- 238000004458 analytical method Methods 0.000 title claims abstract description 30
- 238000000034 method Methods 0.000 title claims abstract description 28
- 238000012360 testing method Methods 0.000 claims abstract description 42
- 238000009826 distribution Methods 0.000 claims abstract description 8
- 238000012545 processing Methods 0.000 claims abstract description 3
- 239000003822 epoxy resin Substances 0.000 claims description 13
- 229920000647 polyepoxide Polymers 0.000 claims description 13
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 11
- 239000000741 silica gel Substances 0.000 claims description 11
- 229910002027 silica gel Inorganic materials 0.000 claims description 11
- 230000010287 polarization Effects 0.000 claims description 10
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 230000003247 decreasing effect Effects 0.000 claims description 2
- 238000013461 design Methods 0.000 abstract description 4
- 238000005520 cutting process Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M13/00—Testing of machine parts
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
-
- 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
- G01L1/241—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 by photoelastic stress analysis
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
The invention provides a rotating machinery blade strength analysis method based on a photoelastic method, S1, a plurality of blade models are manufactured; s2, calibrating a fringe value of each blade model; s3, carrying out load modeling tests on each blade model under different single working conditions; s4, slicing the blade model after the load modeling test is finished; s5, performing a photoelastic test on the blade model slice, and shooting a test image result; s6, processing the test image result, and obtaining a stress analysis result according to the stripe calibration value; and S7, sorting the slice analysis results of different blade models to obtain blade strength analysis results under different working conditions. The stress distribution of the blade in the working process can be effectively obtained, and effective guarantee is provided for the design of the rotating mechanical blade.
Description
Technical Field
The invention belongs to the field of blade strength analysis, and relates to a rotating machinery blade strength analysis method based on a photoelastic method.
Background
The blades are important components forming the rotary machine, and for the high-power rotary machine, the blades are generally arranged in a circumferential ring shape, and the working conditions have the characteristics of high rotating speed, high temperature and complex load change, so that strict requirements are provided for links of design, manufacture, installation and the like of the blades. Therefore, the strength analysis is carried out on the blade, the safe operation of the blade is ensured, and the operation and maintenance cost reduction of related production enterprises is of great significance.
At present, an electrical measurement method is often adopted in engineering application to carry out strength test on a blade, but due to the fact that strain foil arrangement needs to be carried out on a tested object, the problems that three-dimensional strain field testing is difficult, electromagnetic interference resistance of a testing system is high, and dynamic characteristics of the tested object are changed due to contact measurement are often caused.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a rotating machinery blade strength analysis method based on a photoelastic method, which can effectively obtain the stress distribution of the blade in the working process and provide effective guarantee for the design of the rotating machinery blade.
In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:
a rotating machinery blade strength analysis method based on a photoelastic method comprises the following steps:
s1, manufacturing a plurality of blade models;
s2, calibrating a fringe value of each blade model;
s3, carrying out load modeling tests on each blade model under different single working conditions;
s4, slicing the blade model after the load modeling test is finished;
s5, performing a photoelastic test on the blade model slice, and shooting a test image result;
s6, processing the test image result, and obtaining a stress analysis result according to the stripe calibration value;
and S7, sorting the slice analysis results of different blade models to obtain blade strength analysis results under different working conditions.
Preferably, in S1, the blade model is made of epoxy resin.
Further, silica gel is used as a mold, the blade is used as a core mold, the whole blade is poured and wrapped, and after the silica gel is cured, epoxy resin is injected into the silica gel to obtain the epoxy resin model of the blade.
Preferably, in S2, the stress strip value and the strain strip value of the blade model are determined by performing stress calibration on the calibration sample by using the single-arm beam.
Preferably, in S3, the operating conditions include blade rotation speed, air temperature, and speed ramp rate.
Preferably, in S4, the leaf model is cross-sectioned at 95%, 75%, 50%, 25%, 5% of the leaf height.
Further, the thickness of the blade model slice is less than or equal to 1 mm.
Preferably, in S5, the apparatus for performing the photoelastic test includes a light source, a polarizer, a first quarter-wave plate, a blade model slice, a second quarter-wave plate, a polarization testing mirror, and a high-speed camera, which are arranged in sequence.
Further, light rays start from a light source and are changed into polarized light through a polarizing mirror, the polarized light penetrates through the first quarter-wave plate and then passes through the blade model slice, then the polarized light passes through the second quarter-wave plate and then enters the polarization testing mirror, finally the polarized light reaches the high-speed camera, and the high-speed camera records the light path.
Preferably, in S6, the color stripe image recorded by the high-speed camera is converted into a gray scale image, the gray scale image is analyzed by using a shear stress difference method to obtain a full-field shear stress distribution and a main stress trace of the image result, and a stress analysis result is obtained according to the stripe calibration value.
Compared with the prior art, the invention has the following beneficial effects:
according to the invention, an optical test method is adopted to carry out strength test on the blade, so that the problems caused by contact measurement can be effectively solved, and the blade model is analyzed by taking the actual running load of the rotating machinery as a boundary condition, so that an accurate stress analysis result is obtained; and different slices can be obtained according to different working conditions of the tested blade, the mutual influence of the stripes of the traditional photoelastic method is avoided, the measurement error is reduced, and a more reliable strength analysis result can be obtained. The stress distribution of the blade in the working process can be effectively obtained, and effective guarantee is provided for the design of the rotating mechanical blade.
Furthermore, the application of the epoxy resin to the photoelastic method not only can easily find a stress concentration part, but also can determine the stress concentration coefficient, and the epoxy resin has the characteristic that the borne load is stored in a test object in the form of stress stripes, and even if the load is removed or the cutting process is not influenced, the follow-up analysis result is not influenced after the epoxy resin is sliced.
Drawings
FIG. 1 is a flow chart of a blade strength analysis method of the present invention;
FIG. 2 is a schematic diagram of the laser polarized light field of the present invention.
Wherein: 1-a light source; 2-a polarizer; 3-a first quarter wave plate; 4-slicing the leaf model; 5-a second quarter wave plate; 6-a polarization testing mirror; 7-high speed camera.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings:
as shown in fig. 1, the method for analyzing the strength of a rotating mechanical blade based on a photoelastic method specifically includes the following steps:
And 2, taking the epoxy resin raw material of the same batch, and manufacturing a strip calibration sample. And fixing the manufactured calibration sample on a single-arm beam, applying a load on one section of the single-arm beam, recording the stripes on the surface of the calibration sample, obtaining the relation between the stripes and the load, calibrating the stress stripes so as to determine the stress stripe value and the strain stripe value of the blade model.
And 3, determining modeling test conditions according to the number of modeling criteria, and reasonably formulating a modeling test scheme by comprehensively considering various influences of model dimensions, load proportion and the like in the test, wherein the influences comprise blade rotation speed, air temperature, rotation speed increasing and decreasing speed and the like, because the modeling test is carried out by adopting the model blades made of the epoxy resin. And carrying out a modeling test according to a modeling test scheme, adopting different blade models under different working conditions, and carrying out a test on each test blade under a single working condition so as to reduce the mutual influence among stress stripes and reduce test errors.
And 4, slicing the blade model to be analyzed, and in order to obtain the stress distribution of the typical part of the blade, generally taking 95%, 75%, 50%, 25% and 5% of the blade heights of the blade model to sample the cross section slices of the blade model, wherein the slice thickness a is generally not more than 1mm so as to ensure the light transmittance of the slice.
The epoxy resin has the characteristic that the borne load is stored in a test object in the form of stress stripes, and the load is not affected even if the load is removed or the cutting process is carried out, so that the subsequent analysis result is not affected by slicing.
And 5, putting the slices obtained in the step 4 into a laser polarized light field shown in the figure 2.
The laser polarization light field comprises a light source 1, a polarizer 2, a first quarter wave plate 3, a blade model slice 4, a second quarter wave plate 5, a polarization testing mirror 6 and a high-speed camera 7 which are sequentially arranged; the distance between the light source 1 and the polarizer 2 is 10-20cm, the distance between the polarizer 2 and the first quarter-wave plate 3 is 5-10cm, the distance between the first quarter-wave plate 3 and the blade model slice 4 is not more than 10cm, the distance between the blade model slice 4 and the second quarter-wave plate 5 is not more than 10cm, the distance between the second quarter-wave plate 5 and the polarization testing mirror 6 is 5-10cm, and the distance between the polarization testing mirror 6 and the high-speed camera 7 is 10-20 cm.
The light starts from the light source 1, is changed into polarized light through the polarizer 2, the polarized light passes through the blade model slice 4 after passing through the first quarter-wave plate 3, then enters the polarization testing mirror 6 after passing through the second quarter-wave plate 5, and finally reaches the high-speed camera 7, and the light path is recorded by the high-speed camera 7.
And 6, converting the color stripe image recorded by the high-speed camera 7 into a gray image, and analyzing the gray image by using a shear stress difference method. And obtaining the full-field shear stress distribution and the main stress trace through the image, and obtaining a stress analysis result according to the stripe calibration value.
And 7, sorting the photoelastic analysis results of the different blade model slices 4, and finally obtaining the stress distribution of the blades under different working conditions to complete the strength analysis of the blades.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.
Claims (10)
1. A rotating machinery blade strength analysis method based on a photoelastic method is characterized by comprising the following steps:
s1, manufacturing a plurality of blade models;
s2, calibrating a fringe value of each blade model;
s3, carrying out load modeling tests on each blade model under different single working conditions;
s4, slicing the blade model after the load modeling test is finished;
s5, performing a photoelastic test on the blade model slice (4), and shooting a test image result;
s6, processing the test image result, and obtaining a stress analysis result according to the stripe calibration value;
and S7, sorting the analysis results of the different blade model slices (4) to obtain the blade strength analysis results under different working conditions.
2. The method for analyzing strength of a blade of a rotating machine according to claim 1, wherein in S1, the blade model is made of epoxy resin.
3. The method for analyzing the strength of the blade of the rotating machine based on the photoelastic method according to claim 2, wherein the blade is used as a core mold by using a silica gel as a mold, and the entire blade is poured and wrapped, and after the silica gel is cured, an epoxy resin is injected into the silica gel to obtain the epoxy resin model of the blade.
4. The method for analyzing blade strength of a rotating machine according to claim 1, wherein in S2, the stress streak value and the strain streak value of the blade model are determined by using a single-arm beam to perform stress calibration on a calibration sample.
5. The method for analyzing strength of rotating mechanical blade according to claim 1, wherein in S3, the operating conditions include blade rotation speed, air temperature and speed increasing/decreasing rate.
6. The method for analyzing strength of a rotating mechanical blade according to claim 1, wherein in S4, the blade model is cross-sectioned at 95%, 75%, 50%, 25%, 5% of the blade height.
7. The method for analyzing the strength of the blade of the rotating machine based on the photoelastic method of claim 6, wherein the thickness of the blade model slice (4) is 1mm or less.
8. The rotating mechanical blade strength analysis method based on the photoelastic method according to claim 1, wherein in S5, the device for performing the photoelastic test comprises a light source (1), a polarizer (2), a first quarter wave plate (3), a blade model slice (4), a second quarter wave plate (5), a polarization testing mirror (6) and a high-speed camera (7) which are sequentially arranged.
9. The rotating mechanical blade strength analysis method based on the photoelastic method according to claim 8, wherein the light beam from the light source is changed into polarized light by the polarizer, the polarized light passes through the first quarter-wave plate, then passes through the blade model slice (4), then passes through the second quarter-wave plate, then enters the polarization testing mirror, finally reaches the high-speed camera, and the high-speed camera records the light path.
10. The method for analyzing strength of rotating mechanical blade according to claim 1, wherein in step S6, the color stripe image recorded by the high-speed camera is converted into a gray scale image, the gray scale image is analyzed by using a shear stress difference method to obtain a full-field shear stress distribution and a main stress trace of the image result, and the stress analysis result is obtained according to the stripe calibration value.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202111349162.2A CN114112345A (en) | 2021-11-15 | 2021-11-15 | Rotating machinery blade strength analysis method based on photoelastic method |
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| CN202111349162.2A CN114112345A (en) | 2021-11-15 | 2021-11-15 | Rotating machinery blade strength analysis method based on photoelastic method |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101266215A (en) * | 2008-03-13 | 2008-09-17 | 大连理工大学 | Digital photoelasticity full field shear stress automatic determination method |
| CN111397780A (en) * | 2020-03-30 | 2020-07-10 | 中国航发湖南动力机械研究所 | Method for improving rotating stress fringe level value of epoxy resin photoelastic model |
| CN113074848A (en) * | 2021-06-07 | 2021-07-06 | 中国矿业大学(北京) | Optical elasticity testing system and method based on optical amplification technology |
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2021
- 2021-11-15 CN CN202111349162.2A patent/CN114112345A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101266215A (en) * | 2008-03-13 | 2008-09-17 | 大连理工大学 | Digital photoelasticity full field shear stress automatic determination method |
| CN111397780A (en) * | 2020-03-30 | 2020-07-10 | 中国航发湖南动力机械研究所 | Method for improving rotating stress fringe level value of epoxy resin photoelastic model |
| CN113074848A (en) * | 2021-06-07 | 2021-07-06 | 中国矿业大学(北京) | Optical elasticity testing system and method based on optical amplification technology |
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