Characterization of stress-strain behavior of composites using digital image correlation and finite element analysis

This work presents a cost-effective method taking advantage of the full-field measurement capability of digital image correlation (DIC) for a simultaneous assessment of multiple stress-strain relations for fiber-reinforced composites in a principal material plane. The method is based on combining a finite element model based stress calculation and a full-field surface strain measurement in a custom short-beam shear (SBS) test. The unknown constitutive properties are determined through minimization of the square difference between the DIC-measured and the FEM-calculated strains. The robustness of the proposed method has been evaluated using different initial approximations of material constitutive parameters. Explicit derivation and evaluation of the sensitive matrix are not required in the method. Due to geometric nature of stress distribution in the unidirectional short-beam specimen loaded in a principal material plane, the optimization procedure converges rapidly, and is not sensitive to the formulation and parameters in the initial approximation of the constitutive model.