An Implicit Validation Approach for Digital Image Correlation Based Strain Measurements

Abstract

Finnish Funding Agency for Technology and Innovation (TEKES) and the industrial partners of the research project Process Development for Incremental Sheet Forming have supported this research.Abstract-A digital image correlation algorithm for strain measurements with some improvements is introduced and tested. A major problem related to strain measurements with spatial resolution is the lack of simple validation of the results as the overall strain given by the test machine is not applicable as a local strain reference estimate. An implicit error estimation approach based on statistical analysis is introduced and applied to an image test set from a uniaxial tensile test of a planar aluminum test piece. The spatial strain sampling frequency and the measurement accuracy and errors are studied, when varying a few parameters of the algorithm. An intra-validation procedure is in turn used to validate the error estimates.Keywords-error estimation, deformation, material engineering, measurements based on image.