Experimenal analysis of in-plane strain on curved surfaces using transferring techniques

Abstract

A new grid-transferring technique is introduced that allows the strain analysis of flat or curved surfaces of single or double curvature. The technique consists of transferring a grid from the structure to a flat surface by means of a thin, adhesive, transparent ribbon. Information is obtained along a strip, or point-by-point when circles or rosettes are used. The technique is specially suitable for the solution of problems of finite deformation of flexible structures, and its threshold strain is about 0.004. As a verification of the new method, strains obtained on a disc under diametral compression are compared with results already given in the literature. As a general example of application, strains on the anticlastic surface of tubes with and without perforation, and turned inside out, are determined. The method is not influenced by rigid-body motions.