AS&M Digital Image Correlation Services
Analytical Services & Materials, Inc. (AS&M) provides digital image correlation (DIC) services using state-of-the-art cameras and software. We have more than 20 years of experience providing these services to the NASA Langley Research Center, other NASA Centers, and commercial customers. We offered a non-contact shape, deformation (surface strains and displacements), velocity, and operational mode shape measurements using the Video Image Correlation (VIC)-3D system from Correlated Solutions, Inc.
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Digital Image Correlation Finite Element Analysis
What is DIC?
DIC uses pairs of digital cameras to capture images before, during, and after deformation. Each pair of cameras are focused on the same location and multiple pairs of cameras can be synced to capture different sides or areas of a structure.
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The imaged area is painted with a random high contrast (e,g., black speckles on a white surface) and uses pattern recognition to determine the rigid body motion and deformation of the speckled surface. The software can resolve displacements on a sub-pixel level, so with today’s high-resolution cameras that means that displacements less than 0.001 inches are easily obtained.
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The spatial derivatives of the displacements can be used to calculate the full-field surface strains. With high-speed cameras, the temporal derivates of the displacements can be used to calculate the full-field velocities.
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Think of DIC as a non-contacting method that is equivalent to having tens of thousands of strain gages or accelerometers on the structure!
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What is DIC Used For?
DIC is used to measure the deformation of just about any surface that can be painted and has an optical path to the cameras. For example:
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Laboratory coupon testing for elastic and elastic-plastic material behavior.
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Sub-component, component, and full-size structures for operational qualification and analysis validation
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Structural response due to high-speed impacts or ultra high-speed explosives
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Characterization of the response of cracks and delaminations
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Measurement of the behavior of materials and structures subjected to elevated or cryogenic temperatures
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And many other applications in the aerospace, transportation, energy, construction, semi-conductor, and bio-medical industries.
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Examples of DIC
Mars 2020 Rover Heat Shield Ground Qualification Test
Axial Strains in a 0.03 inch Carbon Fiber Bundle
Immediately Before Failure
Strain Localization Due to Grain Structure
Wltra-High Speed Deformation of an Explosive Joint
(1,000,000 frames per second)
