Strain determination based on strain gauge-guided radial basis function and digital image correlation

Abstract

Two methods are proposed to determine structure surface strain fields in the presence of discontinuities. A partition inverse sequence calculation (PISC) method is presented to calculate displacement based on image matching from the second-last to first image, sequentially. The final deformed image is selected as a reference image, and several areas of interest are identified along the crack boundary prior to calculation. A strain gauge-guided partial derivative of a radial basis function (SPD-RBF) method is introduced to obtain strain distributions. Experimental data from strain gauges that adhered to specimen surfaces are applied to estimate shape parameter and obtain guided values, followed by strain calculation based on PD-RBF. Two typical experiments are conducted to verify the validity and accuracy of the PISC and SPD-RBF. Moreover, the proposed methods are successfully applied to evaluate the strain distributions at the crack tip of a cast iron beam. The experimental results further validate the applicability of the proposed methods in handling deformation with discontinuities.