DIC Course Lecture 1

Lecture 1: 2D DIC + Uncertainty quantification (duration:1h00)

This session summarizes and reiterates on the import aspects of the following on-line provided courses:

Outline the basic principles of subset-based digital image correlation to perform displacement measurements.
Digging deeper into 2D DIC and experimental setup issues

Basic principles of DIC: Image matching. Why is a speckle pattern needed ( correspondence problem)? What is subset size and step size (what are their limitations)?
Correlation criterion: Cross correlation vs. Sum of Squared Differences, offset and scaling in lighting.
Interpolation: DIC measures displacements with subpixel accuracy. How to look in between sampled points.
Shape functions: Deformation of the subset for optimal matching according to the deformation process. What order to use?
Optimization routines: How does a basic correlation run works (coarse and refinement) and how to interpret number of iterations.
How do we derive strains
Initial guess and incremental correlation for large deformations
Local versus Global approach
UQ terminology for DIC
Speckles and lighting: how to obtain the ideal DIC images
What is aliasing and how to avoid it?
Impact of non-perpendicular camera alignment
Impact of out-of-plane motion
Impact of camera motion
How does air turbulence influences my images?
Impact of lens distortions
Practical setup guidelines in a 2D DIC setup

The trainee is familiar with the basic parametric settings (subset size, step size, correlation criterion, interpolation, shape function …) in a DIC formalism to measure displacements and knows which ones to use in various circumstances.
The trainee is provided with a roadmap how to setup a 2D DIC experiment and has a good knowledge on possible error sources and how to avoid them