CONSTRUCTING PURE DIGITAL SECONDARY MOIRE PATTERNS

A new method of constructing pure digital secondary moiré patterns of equal-strain fringes is proposed in this paper. By this method, a pure secondary moiré pattern, without trace of primary moiré fringes, is obtained directly from common digital moiré patterns regardless of how low or high the fringe density. The pure secondary moiré patterns eliminate the backnoise of primary fringes and give the strain value at every point over the whole strain field. This technique can significantly increase the measurement accuracy and the range of moiré techniques. © 1990 Society for Experimental Mechanics, Inc.