DIC Systems And Cameras

Digital Image Correlation

Digital Image Correlation, or DIC, is a non-contact optical method that uses one or multiple cameras to measure quantitative values defining the shape, contour, displacement, vibration and strain on various materials.
The values obtained by the DIC system are then used to create visual models of any problems with either strength or structure of the material. Depending on the scale of the system, DIC can be used in very small to huge testing scenarios. Depending on design and use, DIC can either be a 2D or 3D map.

Traditionally, strain gauges, extensometers, or displacement sensors are used to measure changes in the form of material. However, these instruments are unable to generate full strain maps. With Digital Image Correlation, a full strain measurement can be achieved. Since the deformation is determined by comparing multiple images of the test object before and after any deformity, it allows for a broader range of data to be gathered and more complex testing and analysis to be done.

Due to the ease of implementation, quality of output, and versatility when it comes to testing size, DIC has become increasingly popular over the years. Also, advances in computer technology, digital imaging, and cameras have added to the further use of this method in many applications. Since DIC is a non-contact technique, it does not need to physically interact with the test subject. The method may be used in several applications to test the deformation of many types of solids.

Components of Digital Image Correlation Systems

A DIC system typically consists of cameras that capture images of a test subject from multiple angles and specialized software. The cameras then capture multiple, consecutive pictures of the test material during the entire process; before, during, and after applying strain.
The test material is captured by multiple cameras from multiple angles, which are then analyzed by the software. A series of software computations are performed, ultimately outputs a deformation map. To make it more reliable, DIC testing will usually define parameters or requirements of the test that are used to evaluate if the result is successful. These requirements include:

• Quantities-of-interest (QOIs), such as displacement, strain, curvatures, direction and more
• Region-of-interest (ROIs) or the part of the subject material where predictions of expected deformations may occur are made, an
• Field-of-view (FOV), based on the ROI and expected deformity

DIC Cameras

Cameras used in DIC systems need high sensitivity, high resolution, and high frame rates. Depending on the camera model, some more sophisticated equipment will have the cameras embedded with the analysis software for much faster results. There are also different types of DIC testing, the system might use one camera, called 2D DIC, or two or more, which is also called 3D DIC.

DIC Software

Once the testing has been done, the physical strain has been applied to the subject, and the images taken, the DIC images are now processed by software. Depending on the user, they might opt to use commercial (usually closed-source) software or software that has been independently developed (open-source). Choosing what type of software to use relies solely on the user, and depending on the application, the requirements, and other specifications for a particular test, the user might opt for any one over the other.

DIC Applications

DIC can be used in virtually any industry where a physical object will be put under strain, and the structure of that object needs to be secured. Some common examples include:

• Material testing in automotives includes gears, tires, glass and ceramics, vibration analysis, and even high-speed crash testing.
• Aviation and space flight where similar testing is done
• Cancer research, prosthetics and orthotics, bone and tendon testing in medicine
• Material testing for educational research
• Ballistic and explosive testing in the military
• Wear and tear for running shoes and other wearables

Frequently Asked Questions About Digital Image Correlation (DIC) Cameras In Singapore