How Effective is 2D DIC in Materials Testing?
Digital Image Correlation (DIC) is a technique which offers transformative data quality in materials testing applications.
This technique is often portrayed as expensive, but the requisite software and equipment are more accessible than ever. This blog provides a brief overview of 2D DIC and why it can be a highly effective testing option. The information below is based on a webinar presentation by advanced materials testing expert Fadi Abu-Farha, Ph.D. For a deeper look at this topic, you can view the webinar here.
What is 2D DIC?
DIC refers to digital image correlation. In materials testing, this technique uses optical data recorded by one or more cameras to analyze how a material sample changes under stress. Digital images of a material sample are divided into small subsets of pixels (sometimes called facets), where minute changes can be detected through comparison with a reference image.
This methodology is often used for displacement, tension, and strain testing. Traditionally, these tests are based on measurements gathered using tools like strain gages and extensometers. These tools are capable of taking accurate measurements but cannot match the depth and quality of data offered by digital imaging.
2D DIC refers to an implementation using only one camera. By comparison, 3D DIC uses multiple cameras to generate a three-dimensional digital image.
Three-dimensional imaging adds the ability to analyze an out-of-plane deformation.
While additional 3D-driven capabilities are required in some applications, 2D DIC is still useful for a wide array of tests without compromising on quality. It can also be a simpler and more cost-effective option for an organization implementing DIC for the first time.
Measuring the Effectiveness of 2D DIC in Materials Testing
An effective testing solution requires both accuracy and reliability. How effective is 2D DIC in materials testing? Can it match 3D techniques?
Dr. Abu-Farha’s webinar answers these questions with an in-depth quantitative comparison based on practical, industry-standard tests. This study examines multiple material types, multiple types of tests, and the possibility of 2D DIC using commercially available equipment like video extensometers.
We summarize the results.
- How accurate and reliable are 2D DIC Measurements?
Properly calibrated 2D measurements are highly accurate and reliable—data show that even in the materials/tests which showed the biggest divergence between 2D and 3D measurements, the reliability of the final testing results was still not a concern.
Differences between 2D/3D outcomes, for example, are insignificant compared to typical variations in material samples.
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How does 2D DIC measurement affect testing outcomes?
In general, results demonstrate that 2D DIC generates measurements which are extremely close to 3D DIC results. While small deviations in certain measurements are detectable, the final stress/strain curves generated are virtually indistinguishable.
For a much deeper look at this topic, including numerous examples of real DIC tests and a deep-dive quantitative comparison, we recommend watching the full webinar using the link below.