I wish to test some material with tensile testing machine, and capture film of it, with CCD camera, but do not know which camera to use for filming, so I can later use DIC on the recorded video.
If anyone has any information or experience with this method, I would be grateful on given information.
If you have to film rapid events and you are not intersted on thermal field you can find interesting solutions on PHOTRON HIGH SPEED VIDEO site .
Yes the Photron is a nice camera. If you do not need high-speed, you can use just about any camera that can capture digital images. DIC can work on any image sequence with high-contrast and reasonable resolution. And the built in MATLAB cross-correlation can be used for many purposes as well.
You're right Photron's an interesting choice and with that camera would be interesting to work. But to me it is sufficient 50 frames / second frequency, I do not need high-speed, so I wos thinking to use something like the Olympus SZ-30MR digital camera or HD camcorder.
Now it remains the problem of software, I have limited financial resources, I found from Correlated Solutions VIC 2D program that they give me one months free use but maybe I need more time to explore. Is anyone ever worked with them, or do you suggest another manufacturer
I think that it is important which kind of image processing you need. If you use LABVIEW you have a lot of facilities (IMAQ tools) and you can achieve, in relatively simple way, a lot of informations from your matricial image. In other way (this is i.e. my case, depending om your needs, if you need to have deatiled informations there are other techniques like i.e. Wavelet transform.
I am working on my dissertation, by examining the deformation of metals. I will use this method to determine degrees of deformation and stress at certain points of the samples. For now we take DIC as most suitable method, as published results in the literature show when using of these method.
By the way thank you all for your answers.
Ivan, I'm using Correlated Solutions VIC-3D/2D with tensile tests. If you're planning on building a DIC system yourself, you have to be prepared to spend a considerable amount of time to get to the level of performance of the commercial systems. That much said, you can use any sort of camera that gives you the resolution you need. Logitech has a webcam with 5MPixels for instance under 100€. But you will have to correct distortion, calibrate the camera and correct the images, otherwise your measurements will be seriously compromised.
I will use the commercial system, from Correlated Solutions VIC2D. Do you have any work published with this method, I'd like to know more about the DIC method. Can u tell me which coating did you use to obtain random points on the surface of samples for DIC?
And another thing, since you have experience with the method, Can I record a video and then take pictures out of it for DIC, or do I need some special way to record one frame after a nother, so program can to accept them?
We started working with the system very recently and we still don't have any publications.
You should paint the speckle yourself. Use a decent quality airbrush and start by painting a uniform white coating. Then, change the nozzle to spray-in black dots that take 3 to 8 pixels on your image. This simple recipe seems to give us best results. Finally, yes, you can record a video and select the frames you need. But you have to take into consideration the amount of work that option involves. If you use a 25 fr/s camera, a few seconds of video will provide you with too many frames to select from. If you use a commercial system, you will be able to synchronize frame grabbing with maximum force, for instance, and grab just the frames you need. Hope that helps.
It helps a lot, but still have questions :)
I assumed that it will be a large amount of work, but I need to record the whole process of deformation, because only later I will choose a point that I'm interested from thermo-recorded videos. I will use thermal camera to measure temperature, then in that moment of interest I will calculate strains. Did you tray to use white spackles on black uniform coating. I need black coating due to measuring with thermal IR camera?
and one more thing, what program do you use for your research?
We did not. But I'd expect it to work as well. The correlation you are after should in principle be equally attained with either option. The software we're using is VIC2D and VIC3D from Correlated solutions and it is fairly competent. The software for image acquisition is VIC-SNAP, also from Correlated. VIC-SNAP has a software module that allows you to synchronize image capture with an external input, such as a periodic signal from a test machine or any other sort of event after a number of cycles of your choice, which is really, really helpful. I think you can download a demo, but I'm not entirely sure that option works on the demo. it is called Fulcrum. Can you tell me a little more about your research?
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