Full-field assessment of the damage process of laminated composite open-hole tensile specimens. Part I: Methodology

The present paper is the first part of a study dedicated to the assessment of the damage taking place in composite open-hole tensile specimens using full-field strain measurements. It concentrates on the thorough validation of the methodology used to process the full-field data. First, the grid method used to provide the two components of the in-plane displacement field at the surface of the test specimens is described. Then, the data processing procedure to obtain the displacement maps during the test is discussed. The main part of the paper is dedicated to the derivation of strains from displacements, investigating two procedures: local differentiation and polynomial fitting. The effect of the grid is also investigated. Finally, successful experimental results are presented.