NL2026165B1 - Method for analyzing tensile failure performance of 3d printing sample - Google Patents
Method for analyzing tensile failure performance of 3d printing sample Download PDFInfo
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- 238000007639 printing Methods 0.000 title claims abstract description 25
- 238000009864 tensile test Methods 0.000 claims abstract description 39
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/02—Details
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/02—Details
- G01N3/06—Special adaptations of indicating or recording means
- G01N3/068—Special adaptations of indicating or recording means with optical indicating or recording means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0014—Type of force applied
- G01N2203/0016—Tensile or compressive
- G01N2203/0017—Tensile
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0058—Kind of property studied
- G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
- G01N2203/0075—Strain-stress relations or elastic constants
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/026—Specifications of the specimen
- G01N2203/0262—Shape of the specimen
- G01N2203/0268—Dumb-bell specimens
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/06—Indicating or recording means; Sensing means
- G01N2203/0641—Indicating or recording means; Sensing means using optical, X-ray, ultraviolet, infrared or similar detectors
- G01N2203/0647—Image analysis
Abstract
The present invention discloses a method for analyzing the tensile failure performance of a 3D printing sample, comprising the following steps: printing a tensile sample 5 strip by 3D printing; and forming speckles on a surface of the tensile sample strip; placing the tensile sample strip on a tensile test device, and debugging the tensile test device; capturing an original image of the tensile sample strip before test; performing a tensile test; and acquiring images of the tensile sample strip throughout the tensile test; comparing and analyzing the original image and the target images after 10 deformation by using a digital image correlation method to obtain displacement and strain information; and obtaining a stress-strain curve according to the strain information; thus obtaining sample performance parameters and a strain line.
Description
METHOD FOR ANALYZING TENSILE FAILURE PERFORMANCE OF 3D
PRINTING SAMPLE Field of the Invention The present invention belongs to the field of tensile test of 3D printing samples, and specifically relates to a method for analyzing the tensile failure performance of a 3D printing sample. Background of the Invention The statement here merely provides the background art related to the present invention, and does not necessarily constitute the prior art. The traditional research methods of experimental mechanics are contact-type. Among them, the method for pasting a strain gauge is widely used in scientific research and engineering due to its advantages of high precision, simple operation, small size, light weight, large measurement range, etc. However, its precision of test for complex situations decreases. After all, when the strain gauge is pasted to the surface of a sample, it has certain impact on the sample. In addition, a large amount of strain gauges often need to be pasted to the surface of a sample and cannot be recycled. So, this method is greatly restricted in the field of use or the cost of use. The traditional optical measurement methods need complex optical paths (some even require an interference light source), and also need to be performed on vibration isolation platforms, so the experiment is complicated and unlikely to promote in engineering. It is usually assumed that the material is continuous and uniform, regardless of the defects of the material itself, but the anisotropies of products in the manufacturing industry can be seen everywhere. For the new technology of 3D printing, the layer-by-layer stacking molding process makes a product exhibit an anisotropy, and there are many printing parameter settings, such as layer thickness, printing speed, and nozzle temperature. The change of each parameter will atfect the performance of the product, so it is necessary to test the product by using a measurement technology with more comprehensive analysis, which will play a guiding role for this new industry. The introduction of digital image related methods has very important significance for the additive manufacturing industry.
In the existing measurement technology, the general scholars mainly use an electrical measurement method when researching the mechanical properties of printing samples, and propose finite element models of different molded samples. However, due to the molding complexity and anisotropy of the printing samples, these methods generally have defects and do not solve many problems well. Subsequent scholars have improved and amended the above methods, and most of them focused on the printing process. Starting from different printing processes, few scholars have provided more accurate, comprehensive and complete test information data for printing samples from different measurement angles. Some scholars have proposed the use of optical measurement methods, and most of them use some traditional optical measurement means, which have strict requirements for the environmental conditions of experiments, so the optical measurement methods are difficult to promote and use comprehensively. Some other scholars use numerical simulation methods to research sample failure, establish mechanical models to analyze the failure mechanism, and perform numerical simulation research on printing samples in combination with finite element software, wherein most of these methods are supported by certain theories, and the numerical models are to verify the feasibility.
Valid data can be obtained most directly by researching the tensile failure performance of printing samples through experiments. With the continuous improvement of research methods, it is particularly important for research in the field of additive manufacturing. Nahal Aliheidan et al. proposed a method to characterize the fracture resistance and layer-to-layer adhesion of fused deposition modeling 3D printed materials. A double cantilever beam (DCB) acrylonitrile butadiene styrene (ABS) sample was designed and printed with pre-cracks on a “layer” interface, the DCB was loaded in an open mode, and a load-displacement curve was synchronized with optical visualization of a crack tip to detect a critical load at the time of crack initiation. Caterina Casavola et al. measured residual stress of a printing sample, due to cyclic accumulation of residual stress produced by raw materials during the forming process of parts. In order to avoid local enhancement of the strain gauge, an electronic speckle interference method (ESPI) was used to measure the strain gauge. A surface location caused by stress relaxation was determined. Many domestic and foreign scholars have gradually realized that the limitations of electrical measurement methods can find a way out from optical measurement methods. Compared with these traditional optical measurement methods, the digital image correlation method has the advantages of measurement of full-field strain, simple operation, low requirements for environmental conditions, etc., so it is widely used in engineering research. However, the inventors found that the traditional mechanical property test can only obtain a stress-strain relationship curve and its peak strength before the sample fails, which is far from meeting the requirements of development of the additive manufacturing industry and in-depth study on failure properties of printing samples. Summary of the Invention In view of the shortcomings of the prior art, the objective of the present invention is to provide a method for analyzing the tensile failure performance of a 3D printing sample. This method introduces a digital image correlation method into the additive manufacturing industry. With the digital image correlation method for detection, information describing failure characteristics more comprehensively can be obtained.
In order to achieve the above objective, the present invention is implemented by the following technical solution: In a first aspect, an embodiment of the present invention provides a method for analyzing the tensile failure performance of a 3D printing sample, including the following steps: printing a tensile sample strip by 3D printing, and forming speckles on a surface of the tensile sample strip; placing the tensile sample strip on a tensile test device, and debugging the tensile test device; capturing an original image of the tensile sample strip before test; performing a tensile test, and capturing images of the tensile sample strip throughout the tensile test; comparing and analyzing the original image and the target images after deformation by using a digital image correlation method to obtain displacement and strain information; and obtaining a stress-strain curve according to the strain information, thus obtaining sample performance parameters and a strain line.
As a further technical solution, the step of forming speckles on a surface of the tensile sample strip is: spraying a whole side surface of the tensile sample strip with a white matte paint, and then embellishing it with a black matte paint to form speckles uniformly distributed.
As a further technical solution, the step of forming speckles on a surface of the tensile sample strip is: spraying a whole side surface of the tensile sample strip with a black matte paint, and then embellishing it with a white matte paint to form speckles uniformly distributed.
As a further technical solution, when the matte paint 1s sprayed to the tensile sample strip, one or more layers of gauze are spread between the tensile sample strip and a paint nozzle.
As a further technical solution, the tensile test device includes a universal tester, the universal tester is connected to a universal test control system, a CCD industrial camera is arranged in front of the universal tester, and the CCD industrial camera is connected to a computer; and the tensile sample strip is clamped by wedge-shaped clamps in the universal tester.
As a further technical solution, the process of placing the tensile sample strip is: placing the tensile sample strip in the middle of the tensile test device, such that the tensile sample strip is balanced vertically and horizontally, and the side of the sample strip sprayed with speckles faces the CCD industrial camera.
As a further technical solution, the loading speed of the tensile test device, the acquisition speed of the CCD industrial camera, and the brightness of a light source are adjusted before the test.
As a further technical solution, the process of obtaining displacement and strain information is: comparing and analyzing the captured original image and the target images after deformation, then calculating correlations of subsets of the images before and after deformation to obtain relative displacements of center pixels of the subsets before and 5 after deformation, thus obtaining the displacement and strain information.
As a further technical solution, the process of obtaining sample performance parameters is: obtaining a real-time stress-strain curve from the displacement and strain information in combination with the relationship between load and time, and obtaining performance parameters such as tensile strength, elongation, deformation speed and acceleration of the sample in combination with a strain cloud diagram obtained by the digital image correlation method.
As a further technical solution, the process of obtaining a strain line is: obtaining a real-time stress-strain curve of any point from the displacement and strain information in combination with the relationship between load and time, and obtaining the strain line that penetrates left and right and has the maximum strain value in combination with the strain cloud diagram obtained by the digital image correlation method.
Beneficial effects of the present invention are as follows: The present invention introduces a digital image correlation method into the additive manufacturing industry, and uses the digital image correlation method to detect the critical load at the time of crack initiation, so that the information such as full-field strain can be accurately obtained.
The method of the present invention overcomes the defect of inaccurate measurement in the traditional method under the uncertainty of the failure position of the printing sample. A “strain line” penetrating left and right is observed through the strain cloud diagram to determine the tensile failure of the sample strip. The displacement and deformation can be analyzed microcosmically, so the scope is smaller, the precision is higher, and the real deformation and failure law can be reflected.
The method of the present invention overcomes the problems of large errors of measured data given by traditional measurement methods and strict requirements for test conditions, and overcomes the defect in the prior art that the average value of failure of the tensile sample strip obtained only by analyzing the pressure-time curve in the stretching process cannot well reflect the situation of local failure.
The method is ingenious in design and easy to operate, requires low experimental conditions, has high environmental adaptability, and obtains accurate measurement results.
Brief Description of the Drawings The accompanying drawings constituting a part of the present invention are used for providing a further understanding of the present invention, and the schematic embodiments of the present invention and the descriptions thereof are used for interpreting the present invention, rather than constituting improper limitations to the present invention.
FIG 1 is a flowchart of steps of a method for analyzing the tensile fracture performance of a 3D printing sample according to one or more embodiments of the present invention; FIG 2 is a schematic diagram of a tensile test device according to one or more embodiments of the present invention; FIG 3 is a strain cloud diagram of a tensile test according to one or more embodiments of the present invention; FIG 4 is a strain-time relationship diagram given by a digital image correlation method according to one or more embodiments of the present invention; In the figures: 1 universal tester, 2 universal test control system, 3 CCD industrial camera, 4 computer.
In order to show the position of each part, the distance or size between them is exaggerated, and the schematic diagrams are only for schematic use.
Detailed Description of the Embodiments It should be pointed out that the following detailed descriptions are all exemplary and am to further illustrate the present invention.
Unless otherwise specified, all technological and scientific terms used in the present invention have the same meanings generally understood by those of ordinary skill in the art of the present invention.
It should be noted that the terms used herein are merely for describing specific embodiments, but are not intended to limit exemplary embodiments according to the present invention.
As used herein, unless otherwise clearly stated in the present invention, singular forms are also intended to include plural forms.
In addition, it should also be understood that when the terms “contain” and/or “comprise” are used in the description, it indicates the presence of features, steps, operations, devices, ingredients, and/or combinations thereof.
For the convenience of description, the terms “upper”, “lower”, “left” and “right” in the present invention only indicate the upper, lower, left and right directions of the drawings, but do not limit the structure.
They are only for the convenience of description and the simplification of description, do not indicate or imply that the devices or elements must have specific directions or be constructed and operated in specific directions, and therefore cannot be understood as limitations to the present invention.
Interpretation of terms: the terms “mounted”, “coupled”, “connected”, “fixed” and the like in the present invention should be generally understood, for example, the “connected” may be fixedly connected, detachably connected, integrated, mechanically connected, electrically connected, directly connected, indirectly connected by a medium, internally connected between two elements, or interaction between two elements, and the specific meanings of the terms in the present invention may be understood by those of ordinary skill in the art according to specific circumstances.
As described in the background, there are shortcomings in the prior art.
In order to solve the above technical problems, the present invention proposes a method for analyzing the tensile failure performance of a 3D printing sample.
In a typical embodiment of the present invention, a method for analyzing the tensile failure performance of a 3D printing sample is proposed.
This method is implemented in a tensile test device for a printing sample. As shown in FIG 2, the main structure of the device includes: a universal tester 1, a universal test control system 2, a CCD industrial camera 3, and a computer 4. The universal tester is used to stretch a 3D printing sample, the universal test control system is connected with universal tester to control the start and stop of the universal tester, the CCD industrial camera is arranged in front of the universal tester to capture an image when the universal tester stretches the 3D printing sample, and the CCD industrial camera is connected with the computer to store the captured image. In the tensile test of the method of the present invention, the universal tester 1 is provided with supporting tensile clamps, and the tensile clamps are wedge-shaped clamps that clamp the sample reliably for test according to the GB/T 1040-2006 standard. The cleanliness and corrosion of rubber mats inside the clamps need to be checked carefully before use to ensure the availability of the rubber mats of the rubber mats at both ends. The clamps at the upper and lower ends are placed firmly. The distance between the clamps at the both ends of the universal material tester needs to be adjusted according to the size of the tensile sample, so that clamping portions put to both ends of the sample are appropriate, and the sample is ensured to be placed vertically. The analysis on the tensile failure performance of the sample by using the tensile test device for a printing sample is as shown in FIG 1. The specific test method is carried out according to the following steps: L A standard model is established using three-dimensional modeling software SolidWorks, a printing sample (polylactic acid wires may be used) molded by fused deposition is selected, a Tiertime up box printer is used for slicing and supporting the model, and a standard sample strip is printed by a printing method of fused deposition according to relevant GB/T 1040-2006 standards.
2. Before test, a whole side surface of the sample strip is sprayed with a white matte paint, and then embellished with a black matte paint to form appropriate speckles, and vice versa. The speckles are used as important information for comparison before and after deformation, and the speckles are uniformly and randomly distributed. The size of speckle particles is related to an object distance, because the quality of the speckles directly affects the accuracy and precision of the results.
In order to ensure the quality of speckle formation, when the matte paint is sprayed to the sample strip, a layer of gauze is spread between the sample strip and a paint nozzle. In addition, the angle, force and the like of spraying are changed to some extent to ensure better randomness of the speckles sprayed on the surface of the sample.
3. When the tensile sample strip is placed, the tensile sample strip should be balanced vertically and horizontally, which is achieved by adjusting the clamps and using a gradienter, to avoid a horizontal component force during the tensile test.
The printing tensile sample strip is placed in the middle of the universal tester, and the side of the sample strip sprayed with speckles faces the CCD industrial camera, such that a sample strip image appears in the middle of the camera acquisition computer.
4. The CCD industrial camera and the universal material tester are debugged, and the loading speed of the universal tester and the acquisition speed of the camera are adjusted together to achieve an appropriate image acquisition frequency, which will affect its precision. The debugging is performed according to different precision requirements. In this embodiment, the loading speed of the universal tester is adjusted to 0.1 MPa/s, and the acquisition speed is adjusted to 2 fps.
5. A light source is also one of the important factors that affect the accuracy and precision of the results. Generally, ordinary white light is used, but special attention should be paid to the test: first, the image should not be exposed or dark, and second, strobing should be avoided during the test. A DC light source may be added or the brightness of the light source may be adjusted according to the situation on site, so that the lighting effect on site can meet the test requirements, and local exposure and local darkness do not occur on the surface of the sample.
When the brightness of the light source is adjusted, images displayed on the computer should be observed much, or a few images are first shot for analysis, and the light is supplemented with DC light to avoid strobing. If the natural light at the test site meets the requirements, light supplement is not required. In order to avoid the influence of light, a filter may be installed on a lens to better complete the test.
6. After the adjustment as described in steps 3 and 4, an image is shot using the CCD industrial camera as an original reference image before deformation, and stored to the computer as an initial comparison image for later use.
7. The universal tester and the CCD industrial camera are started. The CCD industrial camera is connected to the universal material tester, the universal material tester is triggered to start while the CCD industrial camera is started, images in the whole process that the universal tester stretches the sample strip for test are captured using the CCD industrial camera, and the captured images are used as sequential target images after deformation; and this process continues until the sample strip is broken by stretching, then the universal tester and the CCD industrial camera are turned off, and the image acquisition ends.
8. The original image captured in step 6 and the target images after deformation in step 7 are compared and analyzed by using a digital image correlation method. The basic principle of this method is: surface shape images of the tested object before and after deformation are converted into digital images by an emitron camera or a digital camera, then correlations of subsets of the images before and after deformation are calculated to obtain relative displacements of center pixels of the subsets before and after deformation, and mechanical information such as displacement and strain is obtained accordingly. When searching and matching for correlation calculation is performed in this method, the standard covariance correlation function used is:
AM AM > DVG») lg +141) g,] (2 SVGA] |X Ylearuyiv gf x=—M y=—Af x=M y= M : Where (4) and ZT.) represent gray values of each pixel of the images; In and $= are average gray values of the subsets of the images; u and v are displacements of the centers of the subsets in units of pixel.
9. Real-time image displacement of the sample and strain information of the full field are obtained from step 8, and combined with the relationship between load and time given by the universal tester to obtain a real-time stress-strain curve, and then performance parameters such as tensile strength, elongation, deformation speed and acceleration of the sample can be obtained in combination with a strain cloud diagram given by the digital image correlation method.
Based on the principle of the digital image correlation method, the information indicating the displacement field and strain field of the sample is obtained.
The image can be processed by software such as MATLAB, and the parameters that characterize the basic mechanical properties of the sample can be obtained in combination with the corresponding mathematical operation.
In addition, from the stress-strain curve and the strain cloud diagram, a “strain line” that penetrates left and right and has the maximum strain value is obtained.
A tensile failure is most likely to occur first at the strain line.
The strain line is a result of real-time detection and analysis on the tensile sample by using the digital image correlation method.
The “strain line” that penetrates left and right is a symptom of sample failure, which can realize the prediction of tensile sample failure and more convenient analysis on failure performance.
At the end of the test, the information such as images captured during the test and load time data of the tester may also be saved for future use.
The analysis method of the present invention, which adopts the digital image correlation method introduced for the first time to analyze the tensile failure, is more comprehensive and convenient than the traditional method, completes the description of characteristics of the tensile failure at a lower cost, and obtains more comprehensive information describing the characteristics of failure.
The analysis method of the present invention obtains the full-field strain of the sample from the digital image correlation method, which is combined with the information such as critical load when the universal material tester detects crack initiation at the early stage of failure, tensile strength, elongation, stress-strain curve, Poisson's ratio,
and elastic modulus, to achieve a more comprehensive analysis on the failure mechanism of the printing sample; and the location of failure can be predicted in combination with the stress-strain relationship curve and the strain cloud diagram, which can achieve the prediction of failure of the tensile sample and comprehensive analysis of the failure performance.
According to the present invention, the digital image correlation method is introduced into the additive manufacturing industry for the first time, the relationship between load and time is obtained by the universal material tester, the correlation of images is calculated in combination with the digital image correlation method to obtain full-field displacement and strain data, the whole process of tensile failure development can be obtained in combination with the strain cloud diagram given by this method, then the information such as tensile strength, elongation at failure, stress-strain curve, and critical load and trend of crack initiation before failure can be obtained, and comprehensive description about the tensile failure characteristics of the sample 1s achieved accordingly; and the tensile failure can be predicted, and a stress-strain curve can be given in combination with the relationship between load and time obtained by the universal material tester, thereby achieving a more comprehensive analysis on the tensile failure performance of the sample.
The method of the present invention may also be carried out with a high-speed camera focusing on the failure process at a high-frequency speed, which is combined with the record of the whole process of tensile test by a low-frequency camera to obtain comprehensive and accurate failure analysis.
The present invention provides a simpler and more convenient operation scheme, which gets more attention from the practitioners of the 3D printing industry and achieves comprehensive detection of mechanical properties.
In order that those skilled in the art can understand the technical solution of the present application more clearly, the technical solution of the present application will be described in detail below in combination with a specific embodiment.
This embodiment is implemented in a 3D printing sample strip tensile failure analysis device, by which the tensile failure performance of the sample is analyzed.
The specific test method is carried out according to the following steps:
1. A printing sample molded by fused deposition is selected, a standard sample strip is fabricated according to relevant standards, and the sample strip is sprayed with a matte paint to form speckles. The speckles are an important basis for deformation correlation analysis, so the sizes of the speckles should meet the requirements, and the speckles should be uniformly and randomly distributed.
2. The CCD industrial camera and the universal material tester are debugged, the printing tensile sample strip is placed in the middle of the universal tester, the side of the sample strip sprayed with speckles faces the CCD industrial camera, the loading speed of the universal tester is adjusted to 0.1 MPa/s, the acquisition speed is adjusted to 2 fps, and the brightness of the light source is adjusted to meet the test requirements.
3. After the positions are adjusted as described in step 2, an image is shot using the CCD industrial camera as an original reference image before deformation, and stored tothe computer as an initial comparison image for later use.
4. The universal tester and the CCD industrial camera are started, images in the whole process that the universal tester stretches the sample strip for test are captured using the CCD industrial camera, and the captured images are used as sequential target images after deformation; and this process continues until the sample strip is broken by stretching, then the universal tester and the CCD industrial camera are turned off and the image acquisition ends.
5. The original image captured in step 3 and the target images after deformation in step 4 are compared and analyzed by using a digital image correlation method. The basic principle of this method is: the shapes of the tested object before and after deformation are shot and recorded using the camera, then correlations of subsets of the images before and after deformation are calculated to obtain relative displacements of center pixels of the subsets before and after deformation, and information such as full-field displacement and strain is obtained accordingly. When searching and matching for correlation calculation is performed in this method, the standard covariance correlation function used is:
M M > lens leteruyvy-g,l C(u,v)= —_— 2 Van} |X Dlt vrg] (IJ) xm Af y=M x=M y=-Af Where (43) and SATIE V+V) represent gray values of each pixel of the images; In and 8» are average gray values of the subsets of the images; u and v are displacements of the centers of the subsets in units of pixel.
6. The strain information of the full field obtained from step 5 is combined with the relationship between load and time given by the universal tester to obtain a stress-strain curve, then a critical load and trend of crack initiation before failure can be obtained in combination with the correlation calculation of the digital image correlation method, a “strain line” that penetrates left and right and has the maximum strain value may also be found by observing the strain cloud diagram, a tensile failure is most likely to occur first at the strain line, and the prediction of tensile sample failure and more convenient analysis on failure performance can be achieved based on the symptom that the “strain line” penetrating left and right occurs. Described above are merely preferred embodiments of the present invention, and the present invention is not limited thereto. Various modifications and variations may be made to the present invention for those skilled in the art. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention shall fall into the protection scope of the present invention.
Claims (10)
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| CN202010468579.XA CN111426563A (en) | 2020-05-28 | 2020-05-28 | 3D printing sample tensile failure performance analysis method |
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| NL2026165A NL2026165A (en) | 2021-12-13 |
| NL2026165B1 true NL2026165B1 (en) | 2022-07-07 |
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| NL2026165A NL2026165B1 (en) | 2020-05-28 | 2020-07-29 | Method for analyzing tensile failure performance of 3d printing sample |
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| CN111855432B (en) * | 2020-07-20 | 2021-03-30 | 华中科技大学 | Device and method for testing stress-strain curve of titanium alloy material under high-temperature high-strain rate |
| CN113155615A (en) * | 2021-04-26 | 2021-07-23 | 中国石油大学(北京) | Casing-cement interface fracture toughness testing method |
| CN113984495A (en) * | 2021-10-15 | 2022-01-28 | 中国航发北京航空材料研究院 | High-temperature non-contact deformation measurement precision verification method |
| CN114088520A (en) * | 2021-10-26 | 2022-02-25 | 江苏大学 | Method for measuring uniaxial tension characteristic of noodle belt |
| CN114264542B (en) * | 2021-11-17 | 2024-04-12 | 国高材高分子材料产业创新中心有限公司 | Perforation performance measuring method, equipment and medium based on digital image correlation method |
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