CN107643213B - A kind of high temperature strain measurement method for eliminating off face Influence of Displacement - Google Patents
A kind of high temperature strain measurement method for eliminating off face Influence of Displacement Download PDFInfo
- Publication number
- CN107643213B CN107643213B CN201710638786.3A CN201710638786A CN107643213B CN 107643213 B CN107643213 B CN 107643213B CN 201710638786 A CN201710638786 A CN 201710638786A CN 107643213 B CN107643213 B CN 107643213B
- Authority
- CN
- China
- Prior art keywords
- test specimen
- strain
- cameras
- displacement
- high temperature
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Landscapes
- Length Measuring Devices By Optical Means (AREA)
Abstract
The invention discloses a kind of high temperature strain measurement methods for eliminating off face Influence of Displacement.When the present invention is directed under high temperature with the measurement surface of test piece strain of two-dimensional digital image correlation technique, the measurement error caused by the acoplanarity displacement of test specimen, it proposes one kind and being based on the relevant double camera measurement method of two-dimensional digital image, the surface strain that can be used for test specimen under hot environment measures.It is linear according to virtual strain caused by acoplanarity displacement and object distance, test specimen is imaged in the camera of two different object distances, and then eliminate the influence of acoplanarity displacement, overcomes the problem that traditional measurement method error is big or hardware configuration is complicated.
Description
Technical field
The present invention relates to a kind of high temperature strain measurement methods for eliminating off face Influence of Displacement, belong to contactless high temperature
Field of optical measurements.
Background technology
The strain measurement of test specimen is the important content of Experimental Mechanics, and strain measurement in surface of test piece mainly by pasting under room temperature
The contact measurement methods such as foil gauge, but contact measurement method is no longer practical under high temperature environment, and non-contact measurement
Method can then measure the surface strain information of test specimen under far from high ambient conditions.
Digital Image Correlation Method is a kind of non-contact optical measurement method, passes through two width before and after acquisition test piece deformation
Image can obtain surface strain and the displacement information of test specimen using matching algorithm.Conventional two-dimensional digital image correlation technique exists
When measuring the strain of the surface of test piece whole audience, fail the influence for eliminating test specimen acoplanarity displacement.But because test specimen is flat in actually measuring
Face and camera will not strictly parallel, loading direction and image plane will not strictly parallel, material poisson effect, the high of test specimen warm
Acoplanarity displacement will inevitably occur in the influence of the various factors such as expansion, test specimen.Acoplanarity displacement can lead to putting for test specimen imaging
Big or diminution, causes additional virtual strain.
The works such as Pan Bing, Wang Yuejiao, Gu Yizhuo " it is a kind of characterized for the strain measurement of carbon fiber multifilament and mechanical property it is non-
The influence of acoplanarity displacement is eliminated in contact video measuring system " (ZL.201610757771.4) using doubly telecentric camera lens.It is double remote
Heart camera lens keeps it insensitive to acoplanarity displacement since its distinctive parallel light path designs, but also due to this special light path pattern,
The sample dimensions that can be measured are big as its Lens, and the size so as to cause doubly telecentric camera lens is very big, very stupid
Weight, and its price is very expensive.
" a kind of high-temperature three-dimensional digital image related measurement system and its measurement method " of Pan Bing, Wu great Fang, Xia Yongzhu
(ZL.201010271515.7) Binocular Vision Principle is utilized, the whole audience of test specimen is measured based on three-dimensional digital image correlation technique
Strain.This method needs in advance demarcate two cameras, and common calibration process is cumbersome and stated accuracy is to measuring essence
Degree influences very big.Experimental provision is complicated and expensive, and operation difficulty is also very big, for the technical staff not Jing Guo professional training
It is inconvenient to use.
Invention content
The present invention is to solve the deficiencies in the prior art, proposes that a kind of high temperature for eliminating off face Influence of Displacement is answered
Become measurement method.
The high-temp strain survey that in order to solve the above technical problem, the present invention provides a kind of for eliminating off face Influence of Displacement
Amount method, includes the following steps：
Test specimen is fixedly mounted on high temperature weighted platform by step 1, is made at random in surface of test piece using heat-resisting material
Speckle；
Step 2 fixes two cameras, and two cameras are respectively L with a distance from test specimen1, L2；
Step 3 loads test specimen, record load temperature T and load p, while acquiring test specimen with two cameras and adding
Carry front and back speckle pattern；
The speckle pattern of two camera acquisitions is inputted computer by step 4, is calculated wherein with two-dimensional digital image correlation technique
The strain stress of speckle pattern in one camera1, then utilize two-dimensional digital image correlation technique by two magazine speckle patterns
Match, then calculates the strain stress of speckle pattern corresponding points in another camera by Digital Image Correlation Method2；
Step 5 passes through the object distance L of two cameras1, L2, and the strain stress that measures1,ε2, caused by acoplanarity displacement being eliminated
Virtual strain, and then obtain the logarithmic strain ε that test specimen is generated by load.
Further, two camera lens planes in step (2) are parallel with surface of test piece.
Further, two cameras are unequal with a distance from test specimen in step (2).
Further, step (5) is described as：
Wherein, wherein ε1,ε2The strain measured in respectively two cameras, L1, L2For the object distance of two cameras, ε is test specimen
The logarithmic strain generated by load.
The beneficial effects of the invention are as follows：Compared with prior art, the present invention haing the following advantages：This method using test specimen because
Acoplanarity displacement and the virtual strain and object distance that generate are linear, and logarithmic strain that it is generated by load it is unrelated with object distance this
Test specimen is imaged in the camera of two different object distances, and then eliminates the influence of acoplanarity displacement by one feature, improves measurement accuracy,
It is set to can be applied to the whole audience strain measurement under high temperature.
Compared with using doubly telecentric camera lens, this method can measure large scale test specimen, and visual field is wider.Reduce hardware device
Cost, keep device structure more compact.Compared with using three-dimensional digital image correlation technique, this method does not need two cameras
Relative coordinate, it is only necessary to the object distance of two cameras, therefore eliminate cumbersome camera calibration process.Since this method does not need
The relative position of two cameras, therefore the slight movement of two cameras influences very little to measurement result, compared to 3-dimensional digital figure
As correlation technique, lower, more convenient operation is required to the vibrationproof of measuring environment.
Description of the drawings
Fig. 1 is the high temperature strain measurement schematic device provided by the invention for eliminating off face Influence of Displacement；Wherein, 1- high temperature
Weighted platform；2- test specimens to be measured；3- cameras A；4- cameras B；5- computers；
Fig. 2 is measuring method flow chart provided by the invention.
Specific implementation mode
The present invention is further illustrated in the following with reference to the drawings and specific embodiments.
As shown in Figure 1, the high temperature strain measurement device for eliminating off face Influence of Displacement of the present embodiment includes that high temperature load is flat
Platform, test specimen to be measured, two cameras and the computer containing calculation procedure.
Test specimen in the present embodiment is aluminum alloy materials, camera pixel 1024*1024.The test specimen is fixedly mounted on height
On warm weighted platform, random speckle is made in surface of test piece using heat-resisting material.Fix two cameras, the object distance L of camera A1
For 500 bold and unconstrained rice, the object distance L of camera B2For 300 bold and unconstrained rice, two camera lens planes should be substantially parallel with speckle plan, two
Camera lens plane is no more than 5 degree with speckle pattern plane included angle respectively, guarantee test specimen region blur-free imaging to be measured in two cameras,
That is the region to be measured of test specimen is contained in the coincidence visual field of two cameras, when the temperature at camera place is worked normally not higher than camera
The temperature that can bear.
Test specimen is loaded under high temperature environment, load temperature is 300 degree, load 2kN, while being tried with two camera acquisitions
The speckle pattern of two camera acquisitions is inputted computer, with two-dimensional digital image correlation technique by the part speckle pattern front and back in load
Calculate the whole audience strain stress of speckle pattern in camera A1, then utilize two-dimensional digital image correlation technique by two magazine speckles
Figure matches, then the strain stress of speckle pattern corresponding points in another camera B is calculated by Digital Image Correlation Method2。
Can obtain the logarithmic strain field that test specimen is generated by load is：
It needs to illustrate, in the method for the present invention, object distance L1, L2Can be negative value, object distance positive value represents camera and is located at test specimen front,
Negative value represents camera and is located at test specimen another side, and the two cannot be equal, works as L1, L2One is that just, when one is negative, should ensure that test specimen
The symmetry of tow sides, i.e., the contingency theory value that test specimen tow sides are generated by load are equal.
The principle of the method for the present invention is：The strain that test specimen is generated by load is unrelated with object distance, and test specimen is because of acoplanarity displacement
Caused virtual strain and object distance are linear, and the void that is generated by acoplanarity displacement of two cameras can be pushed away to obtain by pin-hole imaging model
Strain is respectively：
Wherein Δ L is the acoplanarity displacement of test specimen, then the test specimen overall strain that two cameras measure is respectively：
ε1=ε+Δ ε1,ε2=ε+Δ ε2 (2)
Can obtain the logarithmic strain that test specimen is generated by load is：
Claims (2)
1. a kind of high temperature strain measurement method for eliminating off face Influence of Displacement, it is characterised in that：Include the following steps：
Test specimen is fixedly mounted on high temperature weighted platform by step 1, and random dissipate is made in surface of test piece using heat-resisting material
Spot；
Step 2 fixes two cameras, and two camera lens planes are parallel with surface of test piece, and two cameras are with a distance from test specimen
Respectively L1, L2, wherein L1≠L2；
Step 3 loads test specimen, record load temperature T and load p, while acquiring test specimen before load with two cameras
Speckle pattern afterwards；
The speckle pattern of two camera acquisitions is inputted computer by step 4, one of them is calculated with two-dimensional digital image correlation technique
The strain stress of speckle pattern in camera1, then utilize two-dimensional digital image correlation technique to match two magazine speckle patterns, then
The strain stress of speckle pattern corresponding points in another camera is calculated by Digital Image Correlation Method2；
Step 5 passes through the object distance L of two cameras1, L2, and the strain stress that measures1,ε2, void caused by acoplanarity displacement can be eliminated and answered
Become, and then obtains the logarithmic strain ε that test specimen is generated by load.
2. a kind of high temperature strain measurement method for eliminating off face Influence of Displacement according to claim 1, feature exist
In：The step 5 is described as：
Wherein, wherein ε1,ε2The strain measured in respectively two cameras, L1, L2For the object distance of two cameras, ε is test specimen because adding
The logarithmic strain for carrying and generating.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710638786.3A CN107643213B (en) | 2017-07-31 | 2017-07-31 | A kind of high temperature strain measurement method for eliminating off face Influence of Displacement |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710638786.3A CN107643213B (en) | 2017-07-31 | 2017-07-31 | A kind of high temperature strain measurement method for eliminating off face Influence of Displacement |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107643213A CN107643213A (en) | 2018-01-30 |
| CN107643213B true CN107643213B (en) | 2018-07-20 |
Family
ID=61110744
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710638786.3A Active CN107643213B (en) | 2017-07-31 | 2017-07-31 | A kind of high temperature strain measurement method for eliminating off face Influence of Displacement |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN107643213B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109668780B (en) * | 2018-10-16 | 2022-06-07 | 南京林业大学 | Method for continuously detecting internal strain distribution of oriented strand board under load condition |
| CN110057399B (en) * | 2019-03-28 | 2021-05-11 | 东南大学 | Temperature field and displacement field synchronous measurement system and measurement method based on 3D-DIC |
| CN110763146A (en) * | 2019-10-31 | 2020-02-07 | 河海大学 | High-precision optical extensometer and measuring method based on double cameras |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1693874A (en) * | 2005-05-27 | 2005-11-09 | 苏州大学 | High precision measuring method for stretching displacement |
| CN102679899A (en) * | 2012-05-11 | 2012-09-19 | 北京理工大学 | Micro-scale speckle manufacturing method for interface high-temperature deformation measurement |
| CN104236759A (en) * | 2014-09-23 | 2014-12-24 | 北京航空航天大学 | Portable residual stress measurement device and method |
| CN106500612A (en) * | 2016-10-12 | 2017-03-15 | 北京科技大学 | The non-contact measurement system of material members high temperature deformation and method |
| CN106802258A (en) * | 2016-12-13 | 2017-06-06 | 合肥通用机械研究院 | High temperature creep property method of testing based on variable cross-section sample |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004072629A1 (en) * | 2003-02-17 | 2004-08-26 | Nanyang Technological University | System and method for inspection of silicon wafers |
| CN102012215B (en) * | 2010-11-05 | 2012-09-19 | 东南大学 | Digital image-based noncontact optical strain measurement method and strain gauge |
| EP2740075A4 (en) * | 2011-08-02 | 2014-12-31 | Us Gov Sec Navy | System and method for remote full field three-dimensional displacement and strain measurements |
| CN106023193B (en) * | 2016-05-18 | 2018-06-19 | 东南大学 | A kind of array camera observation procedure detected for body structure surface in turbid media |
-
2017
- 2017-07-31 CN CN201710638786.3A patent/CN107643213B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1693874A (en) * | 2005-05-27 | 2005-11-09 | 苏州大学 | High precision measuring method for stretching displacement |
| CN102679899A (en) * | 2012-05-11 | 2012-09-19 | 北京理工大学 | Micro-scale speckle manufacturing method for interface high-temperature deformation measurement |
| CN104236759A (en) * | 2014-09-23 | 2014-12-24 | 北京航空航天大学 | Portable residual stress measurement device and method |
| CN106500612A (en) * | 2016-10-12 | 2017-03-15 | 北京科技大学 | The non-contact measurement system of material members high temperature deformation and method |
| CN106802258A (en) * | 2016-12-13 | 2017-06-06 | 合肥通用机械研究院 | High temperature creep property method of testing based on variable cross-section sample |
Also Published As
| Publication number | Publication date |
|---|---|
| CN107643213A (en) | 2018-01-30 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102003946B (en) | High-temperature three-dimensional digital image related measurement system and measurement method | |
| Pan et al. | High-accuracy 2D digital image correlation measurements using low-cost imaging lenses: implementation of a generalized compensation method | |
| Burke et al. | Qualifying parabolic mirrors with deflectometry | |
| CN107643213B (en) | A kind of high temperature strain measurement method for eliminating off face Influence of Displacement | |
| CN103575227A (en) | Vision extensometer implementation method based on digital speckles | |
| CN108489421A (en) | A kind of fringe projection detection plane component face shape method and device | |
| Chen et al. | High-precision video extensometer based on a simple dual field-of-view telecentric imaging system | |
| Hijazi et al. | Influence of camera’s optical axis non-perpendicularity on measurement accuracy of two-dimensional digital image correlation | |
| CN110806182A (en) | High-precision optical extensometer and measuring method based on telecentric lens | |
| Wu et al. | An accurate method for shape retrieval and displacement measurement using bi-prism-based single lens 3D digital image correlation | |
| Zhang et al. | Accuracy-enhanced constitutive parameter identification using virtual fields method and special stereo-digital image correlation | |
| CN106813594A (en) | Heavy caliber glancing incidence reflects focus lamp high-precision surface shape detection method | |
| Synnergren | Measurement of three-dimensional displacement fields and shape using electronic speckle photography | |
| CN113701657A (en) | Out-of-situ handheld video extensometer and measuring method | |
| CN105783735A (en) | Real-time extensometer measurement method based on two-dimensional digital image correlative compensation algorithm | |
| CN103900495A (en) | Large-diameter mirror plane shape detecting method and device based on stripe reflection | |
| CN111336942A (en) | Shooting method for three-dimensional strain deformation measurement | |
| CN110702505A (en) | Double-view-field video extensometer based on telecentric lens and cubic prism | |
| CN110954253A (en) | Stress measurement method and stress measurement light path device | |
| TW201800717A (en) | Optical interferometric apparatus for real-time full-field thickness inspection | |
| Xie et al. | Tensile test for polymer plastics with extreme large elongation using quad-camera digital image correlation | |
| Hijazi | A novel approach for the determination of surface tilt angles in two-dimensional digital image correlation experiments | |
| CN103543075B (en) | Bendind rigidity method of testing and device under high and low temperature environment | |
| CN203672722U (en) | Bending rigidity testing device used in high-low temperature environments | |
| JP5458263B2 (en) | Displacement / strain measuring device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |