Three-dimensioanl, finite deformation, rate-dependent plasticity in single-crystal nickel alloys at elevated temperatures

摘要

Future increases in gas turbine performance will require numerical algorithms capable of predicting the deformation and rupture of blade materials at elevated temperatures. The current generation of Ni-based superalloys requires constitutive models for rate-deponent plastic deformation of single-crystal turbine blades. Ni-based superalloys show a complicated relationship between temperature adn slip on octahedral or cubic slip systems. Ni-based superalloys show a complicated relationship between temperature and slip on octahedral or cubic slip systems, including softening. A three demsional (3-D) finite deformation algorithm is presented for finite element analysis (FEA) of stress and strain histories in anisotropic elastic materials with rate-dependent slip on specific, multiples slip systems. The FEA includes multiplicative decomposition of the deformation gradients, Hencky strain tensor, and Green-Naghdi stress rate with temperature-dependent crystal slip relations to compute finite deformation, slip induced rotations and material softening. Deformation predictions of Ni-based superalloys are compared with experimental measurements and analytical solutions. Good agreement is found, especially when the specimen-to-specimen variations are considered.