Effective strategy for automated characterization in complex viscoelastoplastic and damage modeling for isotropic/anisotropic aerospace materials

The development of an overall strategy to estimate the material parameters for a class of recent viscoplastic and damage-material models is presented. The procedure is automated through an integrated parameter estimation scheme to enable the determination of an "optimum" set of material parameters by minimizing the errors between the experimental test data and the predicted response. The core ingredients are (1) the numerical experiment simulation analysis, which utilizes a finite-element-based solution scheme; (2) sensitivity analysis utilizing a direct-differentiation approach for the material response sensitivities; and (3) a gradient-based optimization technique of an error/cost function. This scheme is then applied to a variety of materials: (1) an anisotropic polymer matrix composite (PMC); (2) a 9Cr-1Mo material at 550degreesC; (3) a nickel-based Waspaloy at 700degreesC; and (4) a Cu-4 Cr-2 copper-based material at 200degreesC and 400degreesC. These first two materials were characterized for their deformation behavior, and the last two materials are characterized for both deformation and damage behavior. A rather comprehensive set of test conditions (e.g., uniaxial, multiaxial, and cyclic/ratcheting) is considered to demonstrate the scope and effectiveness of the approach.