Digital image correlation (DIC) is a non-contact optical measurement technique to measure 3D full-field displacement, strain, and acceleration using images from digital cameras. Digital image correlation has revolutionized engineering measurements and has evolved from university curiosity towards an industrially accepted technique. It can be used with many tests including tensile, torsion, bending, and combined loading in materials engineering as well as in structural testing for both static and dynamic applications. Our solution embeds the latest tracking and image registration technology for 3D full-field measurement based on changes in images. Behind the nice colorful images, you will find accurate, reliable, and quantitative 3D full-field data everywhere, easily matched to results of 3D finite element analysis. Compared to point measurements with sensors, DIC provides many more insights with limited instrumentation time. These results are used to accurately identify mechanical properties of new and innovative materials, to increase the accuracy and reliability of simulation models based on quantified results, and to accelerate component and system structural validation testing enabling faster and more responsive development cycles. Digital Image Correlation (DIC) is a powerful tool for analyzing deformation of an object. It is based on comparing optical images obtained from a moving and/or deforming object. The comparison of the images allows obtaining displacement vectors of the surface of the image at a very high spatial resolution. If two or more cameras are used, also the out of plane displacements can be obtained. DIC can be compared to as having thousands of mini-extensometers on the sample. The
benefits of DIC include: We use DIC for variety of applications, where we track either displacements or strains of a target during a test. This method is very useful, for example, when studying strain localizations, necking during tensile test, and fracture of a specimen. These all are local phenomena, which would be rather difficult to study with a simple strain gage or extensometer. Recently we have also used the DIC together with infrared imaging, and calibrated the two image modalities to the same coordinate system. This allows measurement of both temperature and deformation of the sample at a very high spatial resolution. This is a very powerful tool for complete analysis of thermomechanical behavior of the material. DIC is also very useful for comparing experimental and simulation results. It may be easy to develop a model that predicts an average strain or average forces, but the detailed comparison of the full field strains requires a very good model. We are always developing our skills and know-how of Digital Image Correlation, and we are looking for new applications of this measurement method. We have developed a measurement tool for analyzing the deformation and movements of the human heart during open-heart surgery. A following video demonstrates our innovation, for which we also have an EPO and US patents pending for approval. Our experimental capabilitiesWe are currently using a commercial DAVIS10 system from LaVision. Low rate system
High rate system
IR:The TELOPS Fast IR-1500 M2K high speed IR camera offers high-speed thermal imaging with high temporal resolution. Therefore, it is ideal to analyse dynamic events.
Simultaneous high speed DIC and IR analysisThe DIC and IR imaging can be carried out simultaneously so that for each DIC image there is a corresponding IR image. Or alternatively the DIC images can be aquired at a higher frequency so that every Nnt image is acquired simultaneously. At low imaging speeds this is quite challenging, but at high rate this is technically a very complex and difficult test. The temporal synchronization together with spatial matching of the two images allows extracting both temperature and strain information on any pixel location of the specimen. We have developed spatial calibration methods that allow spatial synchronization of the images by first calculating the full field displacements from the DIC analysis and applying those vector displacements on the infrared image. This allows careful evaluation of, for example, adiabatic heating in strain localizations, shear bands, necking etc. Other high speed video systemsMemrecam fx K5 Memrecam fx K5 provides ultra high light sensitivity, ultra high speed and mega pixel
Cordin 535-16 Cordin model 535-16 is a High Resolution Rotating Mirror CCD Framing Camera System. This system use a complex optical system centered on a multi-faceted mirror that spins at very high speeds. This action distributes the image to individual CCD channels which record the frames. This approach yields the best image quality available in ultra-high speed applications.
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