CN114858076B - Method for monitoring deformation field in sample - Google Patents
Method for monitoring deformation field in sample Download PDFInfo
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- CN114858076B CN114858076B CN202210471462.6A CN202210471462A CN114858076B CN 114858076 B CN114858076 B CN 114858076B CN 202210471462 A CN202210471462 A CN 202210471462A CN 114858076 B CN114858076 B CN 114858076B
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- 238000000034 method Methods 0.000 title claims abstract description 42
- 238000012544 monitoring process Methods 0.000 title claims abstract description 40
- 239000000463 material Substances 0.000 claims abstract description 63
- 229920005989 resin Polymers 0.000 claims abstract description 51
- 239000011347 resin Substances 0.000 claims abstract description 51
- 238000012360 testing method Methods 0.000 claims abstract description 44
- 238000006073 displacement reaction Methods 0.000 claims abstract description 22
- 238000004458 analytical method Methods 0.000 claims abstract description 17
- 230000000694 effects Effects 0.000 claims abstract description 6
- 238000002360 preparation method Methods 0.000 claims abstract description 6
- 239000011248 coating agent Substances 0.000 claims abstract description 3
- 238000000576 coating method Methods 0.000 claims abstract description 3
- 239000003795 chemical substances by application Substances 0.000 claims description 35
- 239000003822 epoxy resin Substances 0.000 claims description 23
- 229920000647 polyepoxide Polymers 0.000 claims description 23
- 238000005507 spraying Methods 0.000 claims description 23
- 238000002156 mixing Methods 0.000 claims description 20
- 238000007711 solidification Methods 0.000 claims description 13
- 230000008023 solidification Effects 0.000 claims description 13
- 239000000853 adhesive Substances 0.000 claims description 12
- 230000001070 adhesive effect Effects 0.000 claims description 12
- 239000012260 resinous material Substances 0.000 claims 1
- 238000003756 stirring Methods 0.000 description 30
- 238000005259 measurement Methods 0.000 description 15
- 239000003973 paint Substances 0.000 description 12
- 230000008569 process Effects 0.000 description 10
- 238000010586 diagram Methods 0.000 description 5
- 230000008859 change Effects 0.000 description 4
- 238000005266 casting Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000003292 glue Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000011435 rock Substances 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 2
- 238000011068 loading method Methods 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 238000010835 comparative analysis Methods 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000001683 neutron diffraction Methods 0.000 description 1
- 238000007619 statistical method Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
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- 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
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/36—Embedding or analogous mounting of samples
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/36—Embedding or analogous mounting of samples
- G01N2001/364—Embedding or analogous mounting of samples using resins, epoxy
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/36—Embedding or analogous mounting of samples
- G01N2001/366—Moulds; Demoulding
-
- 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)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Sampling And Sample Adjustment (AREA)
- Casting Or Compression Moulding Of Plastics Or The Like (AREA)
Abstract
The invention discloses a method for monitoring a deformation field in a sample, which comprises the following steps: preparation of a transparent sample: resin materials are adopted for layered pouring to obtain transparent samples, scattered spots are sprayed between two adjacent layers of transparent samples, the space positions of the scattered spots of the multiple layers are not overlapped, and a white coating is arranged at the bottom of one end of each transparent sample; displacement field monitoring analysis: and performing test analysis on the internal deformation field of the transparent sample by adopting DIC monitoring equipment, and performing superposition analysis on the refraction effect on the multilayer transparent sample to obtain accurate deformation when the displacement points of scattered spots are extracted. According to the method for monitoring the deformation field in the sample, disclosed by the invention, the transparent sample is obtained by pouring the resin material so as to simulate the sample to be tested, the speckle monitoring points are arranged in the sample, displacement field monitoring analysis is performed by using DIC monitoring equipment, the monitoring of the displacement field and the strain field at different positions in the sample is realized, and the stress and the deformation condition at the corresponding positions in the sample can be further obtained by analysis.
Description
Technical Field
The invention relates to the technical field of strain measurement, in particular to a method capable of monitoring a deformation field in a sample.
Background
At present, in rock tests, an ultrasonic method, a resistance strain gauge, a stress sensor, a photoelastic patch method, a photoelastic strain gauge, a non-contact full-field strain measurement analysis method and a neutron diffraction method are often adopted to monitor the stress strain condition of a sample in the loading process.
The full-field strain measurement analysis method is widely popularized and used due to the advantages of high accuracy, convenient operation and the like. The method combines a digital image correlation technique (Digital Image correlation, DIC for short) and a binocular stereoscopic vision technique, and realizes full-field strain measurement of the surface of the object in the deformation process by tracking speckle images of the surface of the object, wherein the full-field strain measurement comprises three-dimensional coordinate measurement, displacement field measurement and strain field measurement; before the test, black or white speckle monitoring points are sprayed on the surface of the test sample according to the attribute of the test sample, so that the contrast ratio between the monitoring points and the color of the test sample is increased, the movement condition of the speckle in the test loading process is better monitored, and the change of a displacement field on the surface of the test sample is more accurately analyzed. However, in the experimental process, the sample is subjected to surface flaking, flaking or ejection, which causes speckle in the area to drop, and the displacement field of the area and the adjacent area cannot be continuously monitored, so that data is lost. It is worth noting that due to the singularity of the crack tip, when the method is used for monitoring, the real-time displacement field change at the tip cannot be accurately tracked, and the real-time displacement field change can only be derived according to the average value of the displacement of the adjacent data points in the area near the tip, which directly reduces the accuracy and the time delay of the result, and the fracture mechanism of the crack tip area cannot be accurately described. In addition, at present, only the deformation field of the surface of the sample can be tested, the displacement field and the strain field inside the sample can not be tested, and the stress and the deformation condition inside the sample can be deduced, so that the application range of DIC equipment is greatly limited.
Disclosure of Invention
Aiming at the technical problem that the whole-field strain measurement analysis method cannot test the deformation field in the sample in the technology, the invention provides a method for monitoring the deformation field in the sample.
The invention provides a method for monitoring a deformation field in a sample, which comprises the following steps:
preparation of a transparent sample: layering and pouring resin materials to obtain transparent samples, spraying scattered spots between two adjacent layers of transparent samples, wherein the space positions of the scattered spots are not overlapped, and the bottom of one end of each transparent sample is provided with a white coating;
displacement field monitoring analysis: and performing test analysis on the transparent sample by adopting DIC monitoring equipment, and performing superposition analysis on refraction effects of multiple layers of transparent samples to obtain accurate deformation when the displacement points of the scattered spots are extracted, so that the displacement field and the strain field are obtained by monitoring results, and the deformation and the stress at different positions in the sample are obtained according to the displacement fields and the strain fields.
In some embodiments, the resin material is obtained by mixing a proportion of a resin gel and a curing agent.
In some embodiments, the type of resin material and the ratio of the resin gel to the curing agent are selected based on the hardness and brittleness of the test sample to be simulated.
In some embodiments, the preparation of the transparent sample comprises the steps of:
(1) Calculating the mass of the resin adhesive and the curing agent according to the density of the resin adhesive, the density of the curing agent, the proportion of the resin adhesive to the curing agent and the volume of the pouring layer, uniformly mixing the weighed resin adhesive and the curing agent to obtain the resin material, and standing for later use;
(2) Pouring the resin material into a mould, standing and solidifying;
(3) After solidification, spraying scattered spots on the surface of the pouring layer, and standing to dry the scattered spots;
(4) Repeating the steps (1) - (3) to finish multi-layer pouring, and after the final layer pouring is finished, spraying no scattered spots so that the scattered spots are all positioned in the transparent sample;
(5) And after demolding, spraying the bottom surface of one end of the transparent sample to be white.
In some embodiments, the mold is an open-topped cylindrical structure.
The mold may also be of other suitable shape.
In some embodiments, the cylindrical structure has a diameter D and a height D/2.
Preferably, the height of the die of the cylindrical structure is half of the diameter, wherein the diameter D of the cylindrical structure is not particularly limited, and the D value is set according to actual requirements, preferably, D is 50-100mm.
In some embodiments, the resin glue is an epoxy resin, and the mass ratio of the resin glue to the curing agent is (3-5): 1. The stress deformation curve of the transparent sample formed by pouring in proportion accords with the stress-strain curve of the brittle material, and the obtained test result can be better used for optimizing experimental mechanical parameters of the rock material.
In some embodiments, the resin gel and the curing agent are mixed uniformly and then left to stand for 3-5 minutes for later use.
In some embodiments, the resin material is poured into a mold and allowed to stand for a curing time of 8-12 hours.
In some embodiments, the scattered spots are left to dry for a period of 0.5 to 1h.
Compared with the prior art, the invention has the beneficial effects that:
according to the method for monitoring the deformation field in the sample, disclosed by the invention, the transparent sample is obtained by pouring the resin material so as to simulate the sample to be tested, the speckle monitoring points are arranged at different positions in the sample, displacement field and strain field monitoring analysis is performed by using DIC monitoring equipment, so that the displacement fields and the strain fields at different positions in the sample are monitored, and the deformation condition and the stress at the corresponding positions are obtained.
The method for monitoring the deformation field in the sample can be used for forming the deformation process from the surface to different areas in the interior by extracting the deformation field on the surface of a layer of poured test sample and the deformation field on the layer where speckle monitoring points in a plurality of layers of poured samples are located and comparing and analyzing.
Drawings
The foregoing and/or additional aspects and advantages of the invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a schematic diagram of a structure for casting a layer of test sample;
FIG. 2 is a schematic diagram of a structure of a cast two-layer test specimen;
FIG. 3 is a schematic diagram of a structure of a cast three-layer test sample;
FIG. 4 is a schematic diagram of a structure for casting four layers of test samples;
fig. 5 is a schematic diagram of the structure of a cast five-layer test specimen.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative and intended to explain the present invention and should not be construed as limiting the invention.
A method for monitoring a deformation field inside a sample according to an embodiment of the present invention will be described below with reference to the accompanying drawings.
Taking a simulated rock material as an example, the resin adhesive is epoxy resin, and according to the optimal ratio close to the rock-like material strength and the change rule of the brittle material stress-strain curve, the mass ratio of the resin adhesive to the curing agent is 4:1. the casting mold is a cylindrical structure with a diameter of 50mm and a height of 25mm and an open top. It can be appreciated that the cleanliness of the inside of the mold and the flatness of the bottom meet the test requirements.
And calculating the mass of the epoxy resin and the curing agent required when only one layer is poured, namely directly pouring a disc with the diameter D of 50mm and the thickness H of 25mm. The mass of the mixture resin glue poured into the mold can be calculated by using the densities of the epoxy resin material and the curing agent material and the volume of the sample to be poured.
Wherein ρ is the mixing density in g/mm 3 ；ρ 1 Is the density of the epoxy resin, and the unit is g/mm 3 ；ρ 2 The density of the curing agent is expressed in g/mm 3 ；M 1 The mass of the epoxy resin is expressed as g;
volume of sample to be poured:
wherein V is the volume of a sample to be poured, and the unit is mm 3 The method comprises the steps of carrying out a first treatment on the surface of the D is the diameter of the die in mm; h is the height of the die in mm.
The mass of the mixture resin adhesive required for pouring a layer of transparent sample: m=ρv.
Wherein M is the mass of the mixture resin adhesive, and the unit is g.
In order to facilitate statistical analysis of test results, the final formed samples were ensured to be 50mm in diameter and 25mm in thickness.
Comparative example:
as shown in fig. 1, only one layer of test sample is poured, and the specific steps are as follows:
s1, measuring the calculated mass M of the epoxy resin required by pouring only one layer of test sample 1 And mass M of curing agent 1 And (4) uniformly stirring and mixing the two materials along one direction, and standing for 4min for standby, so that bubbles generated by stirring are discharged;
s2, pouring the mixed resin material with the mass M into a mould, initially standing and curing for 10 hours, wherein the loss is not considered for the convenience of explanation, namely M is equal to M 1 And M is as follows 1 And/4. It will be appreciated that in practice there will be process losses, and if process losses are considered, the mass M of epoxy resin required to cast only one layer of test sample is measured at this time 1 And mass M of curing agent 1 The sum of/4 is greater than M;
s3, after solidification is completed, scattered spots are uniformly sprayed on the surface of the material, and the material is stood for 0.5h to enable the scattered spots to be dried;
s4, demolding to obtain a transparent sample with scattered spots on the surface, wherein the transparent sample is not easy to distinguish when DIC monitoring is carried out in consideration of the fact that the poured sample is transparent, and white paint is sprayed at the bottom of one end of the sample without the scattered spots, so that contrast ratio is enhanced, and a better monitoring effect is achieved. After the paint is dried, the paint is left for 1 hour, and then a subsequent test is carried out. Preferably, the speckle is black.
Example 1:
as shown in fig. 2, two layers of test samples were cast. The method comprises the following specific steps:
s1, measuring mass M of epoxy resin 1 And mass M of curing agent 1 And (4) uniformly stirring and mixing the two materials along one direction, and standing for 4min for standby, so that bubbles generated by stirring are discharged;
s2, pouring the mass M/2 mixed resin material into a mold, completing pouring of a first layer, and initially standing and curing for 12 hours;
s3, after solidification is completed, scattered spots are uniformly sprayed on the surface of the material, and the material is stood for 1h to enable the scattered spots to be dried;
s4, measuring mass M of epoxy resin 1 And mass M of curing agent 1 And (4) uniformly stirring and mixing the two materials along one direction, and standing for 4min for standby, so that bubbles generated by stirring are discharged;
s5, pouring the mass M/2 mixed resin material into a mold, finishing pouring of a second layer, standing and curing for 12 hours;
s6, demolding to obtain a transparent sample with a layer of speckle monitoring points inside, spraying white paint on the bottom of one end of the sample, and standing for 1h after the paint is dried to perform a subsequent test.
Example 2:
as shown in fig. 3, three-layer test samples were cast. The method comprises the following specific steps:
s1, measuring mass M of epoxy resin 1 And mass M of curing agent 1 And (4) uniformly stirring and mixing the two materials along one direction, and standing for 4min for standby, so that bubbles generated by stirring are discharged;
s2, pouring the mass M/3 mixed resin material into a mold, completing pouring of a first layer, standing and curing for 12 hours;
s3, after solidification is completed, spraying first scattered spots on the surface of the material, and standing for 1h to enable the first scattered spots to be dried;
s4, measuring mass M of epoxy resin 1 And mass M of curing agent 1 And (4) uniformly stirring and mixing the two materials along one direction, and standing for 4min for standby, so that bubbles generated by stirring are discharged;
s5, pouring the mass M/3 mixed resin material into a mold, finishing pouring of a second layer, standing and curing for 12 hours;
s6, after solidification is completed, spraying second scattered spots on the surface of the sample, standing for 1h to enable the second scattered spots to be dried, and paying attention to that the second scattered spots are not overlapped with the first scattered spots in space positions, adding up surface areas where the two scattered spots are positioned to cover the whole surface of the transparent sample, and preferably, spraying 1/2 surface area of each scattered spot;
s7, measuring mass M of epoxy resin 1 And mass M of curing agent 1 And (4) uniformly stirring and mixing the two materials along one direction, and standing for 4min for standby, so that bubbles generated by stirring are discharged;
s8, pouring the mass M/3 mixed resin material into a mold, finishing pouring of a third layer, and initially standing and solidifying for 12 hours;
s9, demolding to obtain a transparent sample with two layers of speckle monitoring points inside, spraying white paint on the bottom of one end of the sample, and standing for 1h after the paint is dried to perform a subsequent test.
Example 3:
as shown in fig. 4, four layers of test samples were cast. The method comprises the following specific steps:
s1, measuring mass M of epoxy resin 1 And mass M of curing agent 1 And (4) uniformly stirring and mixing the two materials along one direction, and standing for 4min for standby, so that bubbles generated by stirring are discharged;
s2, pouring the mass M/4 mixed resin material into a mold, completing pouring of a first layer, and initially standing and curing for 12 hours;
s3, after solidification is completed, spraying first scattered spots on the surface of the material, and standing for 1h to enable the first scattered spots to be dried;
s4, measuring mass M of epoxy resin 1 And mass M of curing agent 1 And (4) uniformly stirring and mixing the two materials along one direction, and standing for 4min for standby, so that bubbles generated by stirring are discharged;
s5, pouring the mass M/4 mixed resin material into a mold, finishing pouring of a second layer, and initially standing and solidifying for 12 hours;
s6, after solidification is completed, spraying second scattered spots on the surface of the material, standing for 1h to enable the second scattered spots to be dried, and paying attention to the fact that the second scattered spots are not overlapped with the first scattered spots in space position;
s7, measuring mass M of epoxy resin 1 And mass M of curing agent 1 And (4) uniformly stirring and mixing the two materials along one direction, and standing for 4min for standby, so that bubbles generated by stirring are discharged;
s8, pouring the mass M/4 mixed resin material into a mold, finishing pouring of a third layer, and initially standing and solidifying for 12 hours;
s9, after solidification is completed, spraying third scattered spots on the surface of the sample, standing for 1h to enable the third scattered spots to be dried, and taking notice that the third scattered spots are not overlapped with the first scattered spots and the second scattered spots in space positions, adding up the surface areas where the third scattered spots are positioned to cover the whole surface of the transparent sample, and preferably spraying 1/3 surface area of each scattered spot;
s10, measuring mass M of epoxy resin 1 And mass M of curing agent 1 And (4) uniformly stirring and mixing the two materials along one direction, and standing for 4min for standby, so that bubbles generated by stirring are discharged;
s11, pouring the mass M/4 mixed resin material into a mold, completing pouring of a fourth layer, standing and curing for 12 hours;
s12, demolding to obtain a transparent sample with three layers of speckle monitoring points, spraying white paint on the bottom of one end of the sample, and standing for 1h after the paint is dried to perform a subsequent test.
Example 4:
five-layer test samples were cast as shown in fig. 5. The method comprises the following specific steps:
s1, measuring mass M of epoxy resin 1 And mass M of curing agent 1 And (4) uniformly stirring and mixing the two materials along one direction, and standing for 4min for standby, so that bubbles generated by stirring are discharged;
s2, pouring the mass M/5 mixed resin material into a mold, completing pouring of a first layer, and initially standing and curing for 12 hours;
s3, after solidification is completed, spraying first scattered spots on the surface of the material, and standing for 1h to enable the first scattered spots to be dried;
s4, measuring mass M of epoxy resin 1 And mass M of curing agent 1 And (4) uniformly stirring and mixing the two materials along one direction, and standing for 4min for standby, so that bubbles generated by stirring are discharged;
s5, pouring the mass M/5 mixed resin material into a mold, finishing pouring of a second layer, and initially standing and solidifying for 12 hours;
s6, after solidification is completed, spraying second scattered spots on the surface of the material, standing for 1h to enable the second scattered spots to be dried, and paying attention to the fact that the second scattered spots are not overlapped with the first scattered spots in space position;
s7, measuring mass M of epoxy resin 1 And mass M of curing agent 1 And (4) uniformly stirring and mixing the two materials along one direction, and standing for 4min for standby, so that bubbles generated by stirring are discharged;
s8, pouring the mass M/5 mixed resin material into a mold, finishing pouring of a third layer, and initially standing and solidifying for 12 hours;
s9, after solidification is completed, spraying third scattered spots on the surface of the material, standing for 1h to enable the third scattered spots to be dried, and paying attention to that the third scattered spots are not overlapped with the first scattered spots and the second scattered spots in space positions;
s10, measuring mass M of epoxy resin 1 And mass M of curing agent 1 And (4) uniformly stirring and mixing the two materials along one direction, and standing for 4min for standby, so that bubbles generated by stirring are discharged;
s11, pouring the mass M/5 mixed resin material into a mold, finishing pouring a fourth layer, and initially standing and curing for 12 hours;
s12, after solidification is completed, spraying a fourth scattered spot on the surface of the sample, standing for 1h to enable the fourth scattered spot to be dried, and paying attention to that the fourth scattered spot is not overlapped with the first scattered spot, the second scattered spot and the third scattered spot in space position, the surface areas where the fourth scattered spot is positioned are added to cover the whole transparent sample surface, and preferably, each scattered spot is sprayed with 1/4 surface area;
s13, measuring mass M of epoxy resin 1 And a curing agentMass M 1 And (4) uniformly stirring and mixing the two materials along one direction, and standing for 4min for standby, so that bubbles generated by stirring are discharged;
s14, pouring the mass M/5 mixed resin material into a mold, finishing pouring of a fifth layer, and initially standing and solidifying for 12 hours;
s15, demolding to obtain a transparent sample with four layers of speckle monitoring points, spraying white paint on the bottom of one end of the sample, and standing for 1h after the paint is dried to perform a subsequent test.
It is understood that the number of poured layers and the positions of scattered spots are not particularly limited in the preparation of the transparent sample, and the number of poured layers and the positions of the scattered spots are determined according to practical situations.
After pouring, all samples are transparent, and the sprayed speckle monitoring points are contained at different positions inside the samples. The test sample is placed on a test bed, one surface sprayed with white paint faces backwards, the other surface faces forwards and faces against DIC monitoring equipment, meanwhile, a high-speed camera and a matched light source system are placed at a position capable of clearly illuminating the whole test sample, the collection frequency is adjusted, and then the Brazilian split test is carried out through a control testing machine.
The contrast sample is subjected to a contrast test, and the speckle image on the surface of the sample is tracked by utilizing a full-field strain measurement analysis system in combination with a DIC image technology and a binocular stereoscopic vision technology, so that full-field strain measurement of a monitoring area in the deformation process is realized, wherein the full-field strain measurement comprises three-dimensional coordinate measurement, displacement field measurement and strain field measurement. Analyzing the surface deformation field, obtaining a strain cloud picture of the surface in the whole process of sample fracture, and further deducing stress, displacement and the like.
For the test samples of examples 1-4 with the interior sprayed speckle regions, the refractive effect of each poured transparent layer needs to be considered when analyzing the deformation field in the samples, and when extracting the displacement points of the speckle monitoring points, parameter correction needs to be performed to obtain accurate deformation. In particular for multilayer test samples, a superposition analysis of the refractive effects is required.
And extracting deformation fields of the surfaces of the test samples of the comparative examples and deformation fields of the layers of the speckle monitoring points in the multilayer samples, and performing comparative analysis to form deformation processes from the surfaces to different areas in the multilayer samples. In particular, the area adjacent to the center of the specimen where the greatest stress is generated is analyzed, which is helpful for understanding the occurrence of the indirect tensile failure test and the mechanism of rupture.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms may be directed to different embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: many changes, modifications, substitutions and variations may be made to the embodiments without departing from the spirit and principles of the invention, the scope of which is defined by the claims and their equivalents.
Claims (10)
1. A method for enabling monitoring of a deformation field within a sample, comprising:
preparation of a transparent sample: layering and pouring resin materials to obtain the transparent sample, spraying scattered spots between two adjacent layers of transparent samples, wherein the positions of surface areas where the scattered spots are positioned are not overlapped, and the bottom of one end of the transparent sample is provided with a white coating;
displacement field monitoring analysis: and performing test analysis on the internal deformation field of the transparent sample by adopting DIC monitoring equipment, and performing superposition analysis on refraction effects on multiple layers of the transparent sample to obtain accurate deformation when the displacement points of the scattered spots are extracted.
2. The method of claim 1, wherein the resinous material is obtained by mixing a proportion of a resinous gum and a curing agent.
3. The method of claim 2, wherein the type of resin material and the ratio of the resin gel to the curing agent are selected based on the hardness and brittleness of the test sample to be simulated.
4. A method according to claim 3, wherein the preparation of the transparent sample comprises the steps of:
(1) Calculating the mass of the resin adhesive and the curing agent according to the density of the resin adhesive, the density of the curing agent, the proportion of the resin adhesive to the curing agent and the volume of the pouring layer, uniformly mixing the weighed resin adhesive and the curing agent to obtain the resin material, and standing for later use;
(2) Pouring the resin material into a mould, standing and solidifying;
(3) After solidification, spraying scattered spots on the surface of the pouring layer, and standing to dry the scattered spots;
(4) Repeating the steps (1) - (3) to finish multi-layer pouring, and after the final layer pouring is finished, spraying no scattered spots so that the scattered spots are all positioned in the transparent sample;
(5) And after demolding, spraying the bottom surface of one end of the transparent sample to be white.
5. The method of claim 4, wherein the mold is an open-topped cylindrical structure.
6. The method of claim 5, wherein the cylindrical structure has a diameter D and a height D/2.
7. The method according to claim 4, wherein the resin paste is an epoxy resin, and the mass ratio of the resin paste to the curing agent is (3-5): 1.
8. The method of claim 7, wherein the resin gel and the curing agent are mixed uniformly and then left to stand for 3-5 minutes.
9. The method of claim 7, wherein the resin material is poured into a mold and allowed to stand for an initial curing time of 8 to 12 hours.
10. The method of claim 7, wherein the scattered spots are left to dry for a period of 0.5 to 1 hour.
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