The Measurement of Strain Based on Finite Element Theory and Image Method

A large strain measurement program has been developed in Labview, which is based on digital image and finite element theory. It is a new method for strain measurement. This new method includes several steps: marking some circles on surface of the specimen, taking some pictures of the specimen before and after deformation, calculating the exact position of the mark center by the program, comparing the center position, and getting the strain according to the finite element theory. Finally, this paper gives experimental results, which proves the correctness of this method.