Abstract
The full-field principle strains are the most important parameters for instability evaluation. In this study, the microscale principle strain distributions of a carbon fiber reinforced plastic (CFRP) specimen under a three-point bending load were studied using the scanning electron microscope (SEM) moire fringes. The normal strain distributions in the horizontal and the vertical directions, and the shear strain distribution were first measured with the SEM moire method. The maximum as well as the minimum principle strain distributions and their orientation distributions were then determined from the theoritical strain status analysis. The principle strains are not affected by the specimen grating, even if the specimen grating direction is not parallel to the specimen axial direction.
