An experimental investigation of Iosipescu specimen for composite materials

A detailed experimental evaluation of the Iosipescu specimen tested in the modified Wyoming fixture is presented. Moire interferometry is employed to determine the deformation of unidirectional and cross-ply graphite-epoxy specimens. The results of the moire experiments are compared to those from the traditional strain-gage method. It is shown that the strain-gage readings from one surface of a specimen together with corresponding data from moire interferometry on the opposite face documented an extreme sensitivity of some fiber orientations to twisting. A localized hybrid analysis is introduced to perform efficient reduction of moire data, producing whole-field strain distributions in the specimen test sections.