CN101726493A - Method and device for detecting shrinkage and cracking performance of cement-based material - Google Patents
Method and device for detecting shrinkage and cracking performance of cement-based material Download PDFInfo
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Abstract
The invention provides a method and a system for detecting shrinkage and cracking performance of a cement-based material based on image processing technology, and belongs to the field of material detection. The system mainly comprises an image acquisition unit, an image processing unit, a result display unit, a communication unit and the like; the image processing unit comprises an image pre-processing unit, an image enhancing unit and an image analyzing unit, wherein the image pre-processing unit finishes gray conversion of images and selection and shear of an effective area; the image enhancing unit peels a research object and a background image through smoothing, sharpening and gray morphology operation in turn; and the image analyzing unit finishes characteristic extraction of the research object and calculation of the crack width and shrinkage value. The detection method of the invention has the advantages of low computation and high image resolution; and the system has the advantages of stable structure, visual analysis, multiple channels, high precision (20 mum) and good economy, and is applicable to global detection and evaluation for the shrinkage and cracking performance development process of materials such as neat slurry, mortar, concrete and the like.
Description
Technical field
The present invention relates to the material tests field, be specifically related to a kind of method and device that cement-based material shrinkage cracking performance is detected.
Background technology
In technology of producing cement and the concrete preparation technique, the contraction of cement-based material, cracking phenomena can have a strong impact on the volume stability and the endurance quality of material, also are the focuses of Chinese scholars research.Although relevant method of testing is a lot, as utilizing contact method based on length, volume change, carry out the measurement of shrinkage based on the contactless method of sensor and optical principle, but existing method of testing respectively has relative merits: contact method equipment is simple, but precision lower, be subject to the influence of operating personnel's subjective factor; Contactless method has advantage on precision, but has comparatively problems such as complexity, cost height of actual mechanical process, and two kinds of methods all just are applicable to the measurement that different phase is shunk.Along with technical progress, traditional test, the evaluation means of cement concrete obtained further perfect, research method in the more brand-new or cross discipline has also obtained abundant application in test, the monitoring of cement concrete and in estimating, digital image processing techniques are exactly to use comparatively successful a kind of technology, as utilize the frequency histogram function in the digital image analysis software that the pore in the concrete zone to be measured is carried out class test, estimate the pore structure feature in the xoncrete structure; Sample section after utilizing backscattered electron image (BSEI) analytical technology to polishing carries out graphical analysis, and hydrated cement grog is not observed, and according to all represent the not pixel value of hydrated cement phase in every width of cloth image, carries out the test of degree of hydration.
Geng Fei has utilized the Delphi language compilation " crack picture analysis software ", carry out the observation and the evaluation (Southeast China University's master thesis) of concrete plastic crack feature, but because this software mainly is the O﹠A at FRACTURE CHARACTERISTICS, on precision, there is (because the restriction of capture instrument of very big defective, its image resolution ratio is 640 * 480Pixels, realistic accuracy is the millimeter level), if be used for shrinking measurement, its precision is far from being enough.
Summary of the invention
The object of the present invention is to provide and a kind ofly can shrink the system that detects and estimate with cracking performance to cement-based material based on digital image processing techniques.
A kind of cement-based material provided by the invention shrinks and the cracking performance detection system, mainly comprise unit such as image acquisition, Flame Image Process, result's demonstration and communication, image acquisition units is transferred to the image that collects in the graphics processing unit of computing machine by communication unit, image is through handling, and the result is by display unit output as a result; It is characterized in that: described graphics processing unit comprises image pretreatment unit, image enhancing unit and image analyzing unit, wherein:
The image pretreatment unit is finished the gradation conversion of image, the selection and the shearing of effective coverage;
Image enhancing unit is removed in the actual imaging process image fault because of imaging device and environment caused by smoothing processing successively, make the gradation of image contrast strengthen and form complete border by the sharpening processing, by the gray scale morphological operation image that border and border surrounded is carried out the outstanding processing of feature, make treat research object in black white image presenting with the antipodal color of background image, and peel off with background image;
Image analyzing unit is finished the calculating of feature extraction and fracture width and shrinkage value.
In described cement-based material contraction and the cracking performance detection system, the graphics processing unit function is to deliver in computing machine by the image processing software that the MATLAB language forms to realize.
In described cement-based material contraction and the cracking performance detection system, detect, in the described image enhancing unit, comprise also that at last the processing of interpolation convergent-divergent improves the resolution of image at shrinkage; Image analyzing unit will carry out feature extraction and calculating according to the figure after handling through the interpolation convergent-divergent.
In the described cement-based material contraction and cracking performance detection system based on image processing techniques, described computing machine minimalist configuration is: Intel Core 2CPU, the above internal memory of 1G, the above hard drive space of 512M, 32-position OpenGL display card.The described image capture device resolution that is connected with image acquisition units is 7,000,000 above pixels.
Described cement-based material shrink with the cracking performance detection system in, also comprise evaluation unit, with the comparison between the reference data of loading in the result of calculation of finishing graphics processing unit and the evaluation unit, and provide the evaluation suggestion, export by display unit.
Another purpose of the present invention be to provide a kind of degree of accuracy high cement-based material is shunk the method that detects with cracking performance based on digital image processing techniques.
The cement-based material that the present invention is based on image processing techniques shrinks and the cracking performance detection method, uses the above cement-based material to shrink and the cracking performance detection system, may further comprise the steps:
1), the image capture device that links to each other with image acquisition units of utilization carries out image acquisition to sample;
2) image that, collects is transferred in the graphics processing unit of computing machine by data line;
3), image obtains the result of calculation of cement-based material crack width and shrinkage value successively through image pre-service, figure image intensifying and graphical analysis;
4) with the output device output of result by being connected with display unit.
In the described cement-based material contraction and cracking performance detection method, also comprise in the step 3) the comparison procedure between result of calculation and the reference data, and provide evaluation result based on image processing techniques.
Concrete: in the described cement-based material contraction and cracking performance detection method based on image processing techniques, detect at shrinkage, described step 3) comprises following operation in proper order:
Image cut: select to comprise the appropriate area of two reference points, separate from original image in the zone that will contain reference point;
Gradation conversion: the color harmony saturation infromation of removal of images and the brightness that keeps image is converted into gray level image to rgb image;
Smoothing processing: because of the image fault that imaging device and environment caused, extract useful information in the removal actual imaging process, adopt Gauss's low-pass filtering, Wiener filtering and mean filter to realize linear smoothing;
Sharpening is handled: make the enhancing of gradation of image contrast and form complete border, reference point is separated from image;
The gray scale morphological operation: the image that border and border surrounded carried out feature is outstanding to be handled, make treat research object in black white image to present with the antipodal color of background image, reach the effect of peeling off with background image;
The interpolation convergent-divergent is handled: utilize the nearest algorithm that image is amplified, increase the resolution of image under the prerequisite that does not reduce picture quality;
Shrinkage value is measured and is calculated: with t be in the image in 0 moment between two reference points difference of pixel value be initial length L
0, the difference of measuring pixel value between the t moment two reference points respectively is for detecting length L
t, calculate the shrinkage value ε that its difference is t material during the length of time;
ε＝(L
0-L
t)
Concrete: in the described cement-based material contraction and cracking performance detection method based on image processing techniques, detect at cracking performance, described step 3) comprises following operation in proper order:
Image cut: select crannied appropriate area, separate from original image in the zone that will contain the crack;
Gradation conversion: the color harmony saturation infromation of removal of images and the brightness that keeps image is converted into gray level image to rgb image;
Smoothing processing: because of the image fault that imaging device and environment caused, extract useful information in the removal actual imaging process, adopt Gauss's low-pass filtering, Wiener filtering and mean filter to realize linear smoothing;
Sharpening is handled: make the enhancing of gradation of image contrast and form complete border, the crack is separated from image;
The gray scale morphological operation: the image that border and border surrounded carried out feature is outstanding to be handled, make treat research object in black white image to present with the antipodal color of background image, reach the effect of peeling off with background image;
Crack area measurement: obtain the number of pixels that crack area comprises, multiply by the real area of each pixel correspondence with number of pixels;
Fracture width is measured: crack area is carried out the Boundary Extraction operation to obtain crack girth numerical value, use the crack area divided by length again, obtain the crack mean breadth.
Adopt above scheme, the cement-based material that the present invention is based on image processing techniques shrinks and the cracking performance detection method, and wherein image is through after pre-service and strengthening operation, and operand reduces, image resolution ratio improves, and can realize material contracts and two kinds of performance detection of cracking.The cement-based material that the present invention is based on image processing techniques shrinks and the cracking performance detection system, and reasonable in design, compact in design can be finished the detection overall process well.The present invention has (being applicable to clean slurry, mortar, concrete) applied widely, Stability Analysis of Structures, visual analyzing, hyperchannel, precision height (20 μ m), good economy performance, can omnidistance evaluate shrinkage and the advantage of cracking performance.
Description of drawings
Fig. 1-1: be image collecting device one-piece construction synoptic diagram among the present invention.
Fig. 1-2: be image collecting device supporting configuration diagram among the present invention.
Fig. 1-3: for image collecting device sample among the present invention bears plate.
Fig. 1-4a: be image collecting device transversal displacement control lever exploded view among the present invention.
Fig. 1-4b: be image collecting device transversal displacement control lever among the present invention and chute connection diagram.
Fig. 1-5: be image collecting device displacement modulator structure left view, right view and front elevation among the present invention.
Fig. 1-6: be image collecting device length travel control lever among the present invention.
Fig. 1-7: be image collecting device capture equipment clamp structure synoptic diagram among the present invention.
Fig. 2 is the cement-based material shrinkage cracking performance detecting system basic composition figure that the present invention is based on Digital Image Processing.
Fig. 3 is Flame Image Process pie graph among the present invention.
Fig. 3-1 is harvester collection and the sample original image that is transferred to computing machine;
Fig. 3-2 is Fig. 3-1 image synoptic diagram after manually shearing;
Fig. 3-3 is Fig. 3-2 image effect synoptic diagram after gradation conversion;
Fig. 3-4 is Fig. 3-3 image effect synoptic diagram after strengthening;
Fig. 3-5 is the maximum display pixel value of Fig. 3-4 image X-direction;
Fig. 3-6 is the maximum display pixel value of X-direction behind Fig. 3-5 image interpolation convergent-divergent;
Fig. 3-7 is harvester collection and the crack original image that is transferred to computing machine;
Fig. 3-8 is Fig. 3-7 crack pattern picture after binary conversion treatment.
Fig. 4 is used testing process figure among the present invention.
Fig. 5 is that the present invention is to Crack Detection example curve figure.
Embodiment
The present invention adopts digital image processing techniques, utilize relevant apparatus collection, transmission, processing, analysing digital image, calculate the feature of shrinking, ftractureing at material, the trend of shrinking, ftractureing development is described, and at the composition form of cement concrete, the degree and the trend that starting material are influenced its contraction and cracking development are estimated, thereby obtain the detection and the evaluation result of material contracts and cracking performance.
One, cement-based material shrinks with cracking performance and detects evaluation system
The present invention is based on the cement-based material shrinkage cracking performance detecting system of Digital Image Processing, its basic composition is referring to shown in Figure 2, mainly comprise five unit such as image acquisition, Flame Image Process, assay, result's demonstration and communication, wherein, image acquisition is finished by image collecting device (referring to following), the image that collects is transferred in the graphics processing unit of computing machine by communication unit, image is through a series of processing, computing machine carries out fracture width by feature extraction and calculates and the shrinkage assay, and the result is by display unit output as a result.Below the major function unit is described further.
1. image acquisition
The collection of Sample Image when image acquisition units is finished different time points.Image capture device has digital camera (based on CCD or CMOS principle) and video camera etc. at present.Because come the features such as size of rendering image in the computing machine with image resolution ratio, resolution is closely related with the max pixel value of collecting device again, its size directly has influence on the display quality of image, therefore, in order to satisfy the needs of graphical analysis, use high-resolution image capture device as much as possible.Image acquisition uses 7,000,000 above pixel CCD digital cameras to carry out among the present invention.
Concerning the measurement of shrinkage, the collection of all images must be to carry out under identical adopting adopted as the absolute constant prerequisite of equipment maintenance relative position as environment, research object and image, could guarantee that like this research object has identical reference point, measurement result is just more accurate, science.
Therefore, according to the characteristics of cement-based material, the present invention designs as Fig. 1-1 to the image collecting device shown in Fig. 1-7.As Figure 1-1, this image collecting device comprises bearing support 1, transversal displacement control lever 2, length travel control lever 3, displacement modulator 4 and capture equipment anchor clamps 5.Wherein, transversal displacement control lever 2 and length travel control lever 3 mutual vertical racks are located on the bearing support 1, connect by displacement modulator 4 between transversal displacement control lever 2 and the length travel control lever 3, capture equipment anchor clamps 5 are fixedly connected on the lowermost end of length travel control lever 3.
Shown in Fig. 1-2, wherein bearing support 1 is made of pedestal 11, column 12, upper frame 14, and wherein pedestal 11 and upper frame 14 are by having formed bearing support 1 with column 12 welding; Middle part at any relative two frames of upper frame 14 offers chute 13.
Shown in Fig. 1-4a and Fig. 1-4b, transversal displacement control lever 2 is established a displacement control lever 24, is provided with screw thread 23 on the two ends of displacement control lever 24, and transversal displacement control lever 2 also is provided with a plurality of nuts 21 and a plurality of pad 22 that is spirally connected mutually with screw thread 23; Described in the present embodiment nut 21, pad 22 are 4 pairs, nut 21 wherein, two couple in the pad 22 place respectively on the screw thread 23 at displacement control lever 24 two ends, inboard at chute 13, nut 21, pad 22 are spirally connected with screw thread 23, displacement control lever 24 penetrates the chute 13 of bearing support 1, and in addition two pairs of nuts 21, pad 22 are fixed control lever from chute 13 outsides.
Shown in Fig. 1-5, be displacement modulator structural representation of the present invention, displacement modulator 4 is established the embedded hole 41 of level, vertical embedded hole 42 and screw 43, transversal displacement control lever 2 (as Figure 1-1) passes displacement modulator 4 among Fig. 5 by the embedded hole 41 of level, and by screw 43 fixing (shown in Fig. 1-5C), in case the displacement modulator rotates; Length travel control lever 3 (as Figure 1-1) passes displacement modulator 4 (shown in Fig. 1-5) by vertical embedded hole 42 among Fig. 5, and by tightening or unscrew screw 43 (shown in Fig. 1-5A), regulates the displacement size of vertical direction.
Shown in Fig. 1-6, be the synoptic diagram of length travel control lever 3 of the present invention, length travel control lever 3 is provided with safety screw 31 and steel column 32.Safety screw 31 is located at steel column 32 tops of length travel control lever 3, like this in experimentation, even if the screw among Fig. 5 B 43 is too unclamped owing to misoperation, also can be owing to the existence of screw 31, the phenomenon of the whole whereabouts of length travel control lever can not occur, thereby avoid damaging the possibility of capture equipment and sample.
Shown in Fig. 1-7, be capture equipment clamp structure synoptic diagram of the present invention, capture equipment anchor clamps 5 are provided with a plurality of screws 51 and clip slot 52, and clip slot 52 places in the capture equipment anchor clamps 5 (shown in Fig. 1-7D), and three screws 51 are fixed on (shown in Fig. 1-7B) in the clip slot 52 to capture equipment; Capture equipment anchor clamps 5 link together by steel column 32 bottoms of welding with length travel control lever 3;
As Figure 1-3, the present invention also comprises sample and bears plate 6, and it is a steel plate 62 that sample bears plate 6, around steel plate 62, be provided with draw-in groove 61, sample bears plate 6 and is embedded in together mutually with column 12 in the bearing support 1 by draw-in groove 61, and places on the pedestal 11, and sample then is placed on the steel plate 62.
Be combined to form image collecting device of the present invention by above, be used to adjust relative position between digital camera and the sample can collect distinct image.During work, sample to be checked (as prism-shaped cement bar or other size sample) is placed on sample and bears on the plate 6, after digital camera is installed in capture equipment anchor clamps 5 by screw 51, at first unclamp each nut 21 among Fig. 1-4, and mobile transversal displacement control lever 2 position to the sample, tighten each nut 21 to keep sample and capture equipment position relatively stable in the horizontal direction; Unclamp the screw 43 among Fig. 1-5B again, up-down adjustment length travel control lever 3, make digital camera obtain suitable scene depth, and then tighten above-mentioned screw 43, to keep relatively stable in the vertical direction position of sample and digital camera, make like this and adjust digital camera and the stable relative position of sample maintenance, be convenient to the experiment condition of digital camera according to setting, in different time sections sample is carried out the collection of image, to finish different shrinkage cracking performance tests in the length of time.
2. signal transmission
Carry out the signal transmission by communication unit, comprise the transmission of image and the transmission of data.Image is transmitted between capture equipment (digital camera) and the graphics processing unit and carries out, and transmission manner can be cable, movable storage device; Data transmission is at graphics processing unit and carry out between the display unit as a result, can adopt existing binary coding mode to transmit.
3. Flame Image Process
Utilize graphics processing unit to finish to transmitting the series of processes of the image that comes.
It is a lot of to utilize computing machine to carry out the software of Flame Image Process, as Photoshop, Corel Draw, Scion Image etc., but every kind of software can not be accomplished exhaustive, the emphasis that himself is all arranged, mainly bias toward processing as Photoshop to image visual effect, when relating to special dimension, these softwares are just beyond one's ability to help.Graphics processing unit of the present invention is with contraction, cracking feature at cement-based material, utilizes the MATLAB language to form image processing software and delivers in computing machine and realize.Referring to shown in Figure 3, image processing process of the present invention comprises image pre-service, figure image intensifying and the several key steps of feature extraction.
1) image pre-service:
At shrinking measurement image, mainly be that image collecting device collection and the image (shown in Fig. 3-1) that is transferred to computing machine are carried out gradation conversion (rgb image is converted to gray level image), sheared operations such as (selections of effective coverage).To shrink measuring, select to comprise the appropriate area of reference point exactly, be fundamental purpose with outstanding reference point, the data operation quantity that reduces image processing process; Wherein:
Image cut: the zone of containing reference point in the certain limit is separated from original image, the data operation quantity when reducing image processing and analyzing, the image after the shearing is shown in Fig. 3-2.
Gradation conversion: be color harmony saturation infromation, but keep the brightness of image that rgb image is converted into gray level image simultaneously, be convenient to the processing of back by removal of images.Computing machine adjustment meeting automatically selects threshold value to adjust image to image automatically, and effect is shown in Fig. 3-3 after the gradation conversion.
2) figure image intensifying: image enhancement technique is not consider the reason of image deterioration, the unwanted index that decays, and only interested feature is given prominence to, as giving prominence to the object profile, removing each noise like etc.Its objective is improve the sharpness of the feature of studying in image.Need carry out operations such as level and smooth, sharpening, gray scale morphology, interpolation convergent-divergent in the enhancement function.
The smoothing processing of image that is to say the denoising processing, mainly is in order to remove in the actual imaging process, because of the image fault that imaging device and environment caused, extracts useful information.Adopt Gauss's low-pass filtering, Wiener filtering and mean filter to realize linear smoothing.
The effect of sharpening is that the gray scale contrast is strengthened, because edge and profile all are positioned at the place of gray scale sudden change.The main sharpening function that adopts is strengthened the edge and the details of reference point, to form complete border, reaches the purpose that reference point is separated from image.
The research feature is carried out after the Boundary Detection operation, just need carry out the outstanding processing of feature to the image that border and border surrounded, make treat research object in black white image to present with the antipodal color of background image, reach the effect of peeling off with background image, with the outstanding feature of being studied, that is to say the processing of gray scale morphology.The image of sample to be tested after figure image intensifying (comprising level and smooth, sharpening, three steps of gray scale morphology) is handled as shown in Figure 3-4.
Changing the image size has dual mode, and a kind of is under the prerequisite that does not change image resolution ratio, increases the display size of image, and another kind is not change under the condition of picture display size, changes its resolution.Utilize interpolation convergent-divergent related function then can realize the latter's target, and this function is the most key one, even if dispose higher digital camera in the market because utilize, the image resolution ratio of being gathered still can't reach the high-precision requirement in the shrinkage test, utilize the interpolation zoom function then can under the prerequisite that does not reduce picture quality, increase the resolution of image, for the measurement of shrinkage is given security.
Fig. 3-5 has shown the maximum display pixel value of (identical with Fig. 3-4) X-direction in the image selection zone, its max pixel value is 1662.75, distance is known as 22cm between two reference points, therefore its resolution is 220000 microns/1662.75 pixels, be 132.5 microns/pixel, that is to say that pixel of every change will bring 132.5 microns variation, therefore, its full accuracy is 132.5 microns, and this is far from being enough for the measurement of shrinking.Utilize the nearest algorithm (conventional algorithm of operand minimum) in the interpolation zoom function to carry out 32 times of effects after the amplification shown in Fig. 3-6, show that its maximum pixel is 53192.5 this moment, resolution is 220000 microns/53192.5 pixels, be 4.14 microns/pixel, that is to say that full accuracy can reach 4.14 microns, take all factors into consideration the various inevitable error in the practical operation, utilize this software to shrink and to reach 10 microns precision when measuring.If simple utilize to improve adopt as the performance of equipment then high precision can't realizing, therefore, the present invention is used for the equipment that contraction fissure measures with other and compares, it is little to the dependence of adopting picture equipment.
Utilization interpolation zoom function has improved the resolution of image greatly, has also increased the operand of computing machine.Popular 1G internal memory, the configuration of double-core CPU can be satisfied the requirement of 32 times of amplifications fully on the market, especially computing power is upgraded so fast today, the 2G internal memory has obtained application to a certain degree on market, the CPU of 4 nuclears even 8 nuclears also puts on market, therefore, under this condition, precision can be further improved along with the renewal of computing power.
Computing machine is not only the display platform of image acquisition, pre-service, feature extraction, measuring accuracy etc., and is interconnective bridge between the different units, is central nervous system, and the height of its performance directly has influence on the precision and the speed of image analysis processing.The update speed of business computer is very fast in the market, its performance also is greatly improved, display device has developed into liquid crystal from CRT, CPU has developed into double-core from monokaryon, even multinuclear, speed and precision that this has all promoted Flame Image Process greatly also provide good platform for Flame Image Process.
In Digital Image Processing and analytic process, can relate to the lot of data computing, so the configuration of the speed of running software and precision and computing machine just there is direct relation.In order to obtain treatment effect preferably, minimum computer configuration is: Intel Core 2CPU, the above internal memory of 1G, the above hard drive space of 512M, 32-position OpenGL display card, if be higher than above-mentioned configuration, then can obtain better treatment effect.
For the crack pattern picture, need binary conversion treatment is adopted in image collecting device collection and the image (referring to Fig. 3-7) that is transferred to computing machine, comprise with above identical image pre-service and figure image intensifying in level and smooth, sharpening, gray scale morphology handle, making background is white, and the crack is black (referring to Fig. 3-8).
3) feature extraction
Feature extraction is finished by image analyzing unit.Feature extraction is exactly to measure the feature of research object, as contraction, cracking feature and other performance.
In the image analyzing unit, the realization of " shrink and measure " function mainly is based on the variation (shrinkage value) of measuring the distance between two reference points on the sample.Specific operation process: two reference point analyses on the sample are numbered A, B, and t represents the length of time, A
t, B
tRepresent t reference point pixel value in software during the length of time.The figure of sample to be tested is amplified to suitable multiple when utilizing the interpolation magnify tool with different length of time, and the mouse pointer of aciculiform is placed on A point in the image, the pixel value A of record this point that system shows this moment
rUnder same enlargement factor, the B point is carried out same operation.T is the poor (B of pixel value between two reference points in 0 constantly the image
0-A
0) be initial length L
0, represent 22mm, be example with Fig. 3-6, initial length is 53192.5 pixels, that is to say 4.14 microns/pixel; (B in the time of can getting t equally and be 1 day
1-A
1) be 53060.31 pixels, calculate as can be known that the length of sample has reduced 132.19 pixels after 1 day, promptly there is the contraction of 547.27 microstrains to produce.The calculating of shrinkage value is suc as formula shown in the 3-1:
ε=(L
0-L
t) (formula 3-1)
ε in the formula: be shrinkage value;
L
0: the initial distance between the reference point (Pixels), i.e. B
0-A
0
L
t: t is the distance between the reference point (Pixels) during the length of time, i.e. B
t-A
t
In the graphics processing unit, " cracking feature " function realizes mainly being based on area of cracks, the fracture width in the crack that occurs on the sample are measured.
Specific operation process:
1, utilize image capture device, take the step in above-mentioned 1, image acquisition is carried out in the zone that occurs the crack in the sample to forming, referring to Fig. 3-7;
2, utilize above-mentioned 3 step, binary conversion treatment is carried out in the crack in the image, handle the back image referring to Fig. 3-8;
3, select (the image pre-service and to strengthen the crack, back be black of zone to be measured after the Flame Image Process, referring to Fig. 3-8), utilize " crack area measurement " and " fracture width measurement " instrument in the graphics processing unit, the detection of the cracking eigenwert of can directly being correlated with.
Crack area measurement:, multiply by the real area of each pixel correspondence again with number of pixels according to the number of pixels that crack area comprises.
Fracture width is measured: crack area is carried out the Boundary Extraction operation, can obtain girth like this, length is approximately half of girth, uses area divided by length again, so just obtains mean breadth.
4. assay:,, estimate the influence of starting material to contraction, cracking performance and development trend thereof in conjunction with the cement-based material composition form of benchmark according to results such as the shrinkage value that detects and incipient crack time, fracture widths.
With the size of shrinkage value and maximum crack width, the morning and evening of incipient crack time etc. is an index, and with the comparative analysis of benchmark sample, the research starting material are to the control ability of concrete shrinkage and cracking performance.The shrinkage value that system-computed is gone out, maximum crack width be for detecting numerical value, compares with the correlation values of benchmark sample, detects numerical value more less than the correlation values of benchmark sample, illustrates that article to be measured have strong more anti-shrinkage cracking performance.
Need to prove that evaluation portion is not a necessary process of the present invention, but can be used as the continuity that the present invention detects.Evaluation result needs to decide according to the concrete condition of sample to be checked, need be complementary with the situation of benchmark sample, industry development.
5. output unit as a result
The display that mates with computing machine is the display platform of image acquisition, pre-service, feature extraction, measuring accuracy etc., also can be used as the output unit of computing and evaluation result; Can also adopt output device as a result of such as printer, USB interface.
Two, cement-based material shrinks with cracking performance and detects and evaluation method
Referring to shown in Figure 4, the measurement flow process of cement-based material contraction of the present invention with the cracking feature can be summarized as follows:
1) sample is prepared: according to GB/T 50080, in conjunction with the experimental program moulding cement mortar and the concrete sample of design, and maintenance is to the specific length of time.
2) utilize image collecting device, sample is carried out the image acquisition in 1,3,7,14, the 28 day length of time respectively, image acquisition is spaced apart 3 width of cloth/sample; The image IMU of gathering is crossed cable transmission to computing machine;
3) computing machine carries out image pre-service, figure image intensifying and feature extraction successively to the view data of obtaining;
4) computing machine utilizes embedded software to draw crack evaluation and shrinkage result of calculation;
5) computing machine output testing result.As the data of benchmark sample are housed in the computing machine, also will compare analysis, the output evaluation result.
Wherein, the described image pre-service of step 3) comprises the process of image being carried out successively adjusted size and gradation conversion; Described figure image intensifying comprises carries out operations such as smoothing processing, sharpening processing, gray scale morphology, interpolation convergent-divergent respectively to pretreated image; Described feature extraction comprises that FRACTURE CHARACTERISTICS is calculated and the calculating of shrinkage value.
Describe the present invention in detail below in conjunction with specific embodiment.Embodiment is only for specifying detection scheme of the present invention, not as the restriction to other embodiment of the present invention.
Test samples:
The shrinkage value test samples: compact dimensions is the cement mortar of 25 * 25 * 275cm (prism-shaped), and wherein sample 1 is not mixed economization agent, and sample 2 mixes 1% economization agent.
The characteristic of crack test samples: 60 * 60 * 7.5cm concrete sample, wherein, Ref: benchmark sample, G-1: economization agent 1% volume, G-2: economization agent 2% volume, G-5: economization agent 5% volume.
Operating process: the sample that together is placed on image collecting device behind the two contraction sample labels is born on the plate, relative position between adjustment digital camera and the sample is at 30cm, open digital camera and computing machine, after moulding, sample is taken pictures during the 1 day length of time and the image of gathering is transferred to computing machine, computer recording and display image in real time.For the shrinkage test, the reference point of pressing the sample mark is as measured zone; For the crack performance test, after image showed that the crack occurs, the time of this moment was just counted the incipient crack time (the initial point time corresponding of every curve among Fig. 5).Requirement according to the needed optimum efficiency of Flame Image Process, image is carried out pre-service (gray scale adjustment), figure image intensifying a series of images adjustment operations such as (smoothly, filtering, interpolation convergent-divergents etc.), and study the calculation procedure of feature (FRACTURE CHARACTERISTICS or shrinkage value), obtain the shrinkage value ε and the different time fracture width of different time.
Testing result: calculate different time sample shrinkage value result referring to table 1, different time fracture width testing result is seen Fig. 5.
By analytical table 1 as can be known, the shrinkage value of interim sample 2 of the same age is less than sample 1, show that mixing of economization agent reduced the shrinkage value in the different length of times, and this effect more obvious in early days (sample 2 shrinkage value in the time of 1 day has just reduced by 44%), this effect of later stage weakens (having reduced by 34% as sample 2 shrinkage value 28 days the time) to some extent, illustrate that economization agent has reduced the cement stone shrinkage value in the different length of times, but thisly reduce to act on more obvious in early days that there be weakening to a certain degree in the later stage.By shrinkage and the development trend thereof of having improved sample 2 of mixing to the comparative descriptions economization agent of two samples.
Table 1 is mixed economization agent cement mortar shrinkage value result of calculation
Maximum crack width: compare with the benchmark sample, mix SRA-G economization agent sample during the 28 day length of time breadth extreme be reduced to 0.342mm by 0.875mm, reduced by 61%, mix SRA-N economization agent sample and be reduced to 0.358mm, reduced by 59.1%.
Analyze: by postponing the incipient crack time, reduce maximum crack width in different length of time, economization agent mix the obvious resistivity of concrete that improved to the early-age shrinkage cracking.
Claims (10)
1. a cement-based material shrinks and the cracking performance detection system, mainly comprise unit such as image acquisition, Flame Image Process, result's demonstration and communication, image acquisition units is transferred to the image that collects in the graphics processing unit of computing machine by communication unit, image is through handling, and the result is by display unit output as a result; It is characterized in that: described graphics processing unit comprises image pretreatment unit, image enhancing unit and image analyzing unit, wherein:
The image pretreatment unit is finished the gradation conversion of image, the selection and the shearing of effective coverage;
Image enhancing unit is removed in the actual imaging process image fault because of imaging device and environment caused by smoothing processing successively, make the gradation of image contrast strengthen and form complete border by the sharpening processing, by the gray scale morphological operation image that border and border surrounded is carried out the outstanding processing of feature, make treat research object in black white image presenting with the antipodal color of background image, and peel off with background image;
Image analyzing unit is finished the calculating of feature extraction and flaw size and shrinkage value.
2. shrink and the cracking performance detection system according to the described cement-based material of claim 1, it is characterized in that: described graphics processing unit function is to deliver in computing machine by the image processing software that the MATLAB language forms to realize.
3. shrink and the cracking performance detection system according to claim 1 or 2 described cement-based materials, it is characterized in that: detect at shrinkage, in the described image enhancing unit, comprise also that at last the processing of interpolation convergent-divergent improves the resolution of image; Image analyzing unit will carry out feature extraction and calculating according to the figure after handling through the interpolation convergent-divergent.
4. shrink and the cracking performance detection system according to the described cement-based material of claim 3, it is characterized in that: described computing machine minimalist configuration is: Intel Core 2CPU, the above internal memory of 1G, the above hard drive space of 512M, 32-position OpenGL display card.
5. shrink and the cracking performance detection system according to the described cement-based material of claim 3, it is characterized in that: the described image capture device resolution that is connected with image acquisition units is 7,000,000 above pixels.
6. shrink and the cracking performance detection system according to claim 1 or 2 described cement-based materials, it is characterized in that: also comprise evaluation unit, with the comparison between the reference data of loading in the result of calculation of finishing graphics processing unit and the evaluation unit, and provide the evaluation suggestion, export by display unit.
7. the cement-based material based on image processing techniques shrinks and the cracking performance detection method, it is characterized in that: use the arbitrary described cement-based material of claim 1-5 to shrink and the cracking performance detection system, may further comprise the steps:
1), the image capture device that links to each other with image acquisition units of utilization carries out image acquisition to sample;
2) image that, collects is transferred in the graphics processing unit of computing machine by data line;
3), image obtains the result of calculation of cement-based material crack size and shrinkage value successively through image pre-service, figure image intensifying and graphical analysis;
4) with the output device output of result by being connected with display unit.
8. shrink and the cracking performance detection method according to the described cement-based material of claim 7, it is characterized in that: also comprise in the step 3) the comparison procedure between result of calculation and the reference data, and provide evaluation result based on image processing techniques.
9. shrink and the cracking performance detection method according to the described cement-based material based on image processing techniques of claim 7, it is characterized in that: detect at shrinkage, described step 3) comprises following operation in proper order:
Image cut: select to comprise the appropriate area of two reference points, separate from original image in the zone that will contain reference point;
Gradation conversion: the color harmony saturation infromation of removal of images and the brightness that keeps image is converted into gray level image to rgb image;
Smoothing processing: because of the image fault that imaging device and environment caused, extract useful information in the removal actual imaging process, adopt Gauss's low-pass filtering, Wiener filtering and mean filter to realize linear smoothing;
Sharpening is handled: make the enhancing of gradation of image contrast and form complete border, reference point is separated from image;
The gray scale morphological operation: the image that border and border surrounded carried out feature is outstanding to be handled, make treat research object in black white image to present with the antipodal color of background image, reach the effect of peeling off with background image;
The interpolation convergent-divergent is handled: utilize the nearest algorithm that image is amplified, increase the resolution of image under the prerequisite that does not reduce picture quality;
Shrinkage value is measured and is calculated: with t be in 0 constantly the image between two reference points difference of pixel value be initial length L0, measure respectively t constantly between two reference points difference of pixel value calculate the shrinkage value ε that its difference is t material during the length of time for detection length L t;
ε＝(L
0-L
t)
10. shrink and the cracking performance detection method according to the described cement-based material based on image processing techniques of claim 7, it is characterized in that: detect at cracking performance, described step 3) comprises following operation in proper order:
Image cut: select crannied appropriate area, separate from original image in the zone that will contain the crack;
Gradation conversion: the color harmony saturation infromation of removal of images and the brightness that keeps image is converted into gray level image to rgb image;
Smoothing processing: because of the image fault that imaging device and environment caused, extract useful information in the removal actual imaging process, adopt Gauss's low-pass filtering, Wiener filtering and mean filter to realize linear smoothing;
Sharpening is handled: make the enhancing of gradation of image contrast and form complete border, the crack is separated from image;
The gray scale morphological operation: the image that border and border surrounded carried out feature is outstanding to be handled, make treat research object in black white image to present with the antipodal color of background image, reach the effect of peeling off with background image;
Crack area measurement: obtain the number of pixels that crack area comprises, multiply by the real area of each pixel correspondence with number of pixels;
Fracture width is measured: crack area is carried out the Boundary Extraction operation to obtain crack girth numerical value, use the crack area divided by length again, obtain the crack mean breadth.
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