Non-destructive strain determination based on phase measurement and radial basis function

A method of non-destructive strain field determination based on the combination of the temporal phase measurement interferometry (TPMI) with radial basis function (RBF) was proposed in this paper. The quality of unwrapped phase obtained by TPMI was improved after RBF interpolation. Then accurate displacements can be obtained, followed by the strain components calculated by employing point-wise local least-squares fitting technique. Optimal sampling intervals of images with different sizes were given based on numerical experiments. For validation, the normal strain distributions in y direction of an aluminum plate subjected to uniform tensile loading were determined by the proposed technique and compared with values measured by strain gauge. The results are in good agreement with each other. Besides, strain distribution of a three-point bending beam with pre-notch was evaluated by the proposed method and the strain gauge technique. Comparison of the results reveals the effectiveness and feasibility of the proposed method.