The effect of material behaviour on the analysis of single crystal turbine blades: Part II – Component analysis

This paper describes the analysis of a turbine blade component using a slip system model developed for modern single-crystal superalloys. Structural elasto-viscoplastic calculations are carried out for the component. The emphasis throughout is on the effect of micromechanisms of deformation, accounted for in the material model, on the predicted overall behaviour of the component. With the recent proliferation in detailed material models that are available, it is prudent to take a step back and investigate the implications of such models for component analysis and design. This effect is manifested through the determination of a stabilised and redistributed stress state throughout the component. While some components are creep-limited in design, many are fatigue-limited and it is stabilised stresses which control the cyclic life of these components. The accuracy of the material model, incorporating various micromechanisms as a function of stress and temperature, can significantly effect these stabilised stresses. The effect of the crystallographic orientation on blade behaviour is illustrated and the implications of shakedown simulations for fatigue lifing of turbine blades are discussed.

[1]  Noel P. O’Dowd,et al.  Gradient-dependent deformation of two-phase single crystals , 2000 .

[2]  Georges Cailletaud,et al.  Single Crystal Modeling for Structural Calculations: Part 1—Model Presentation , 1991 .

[3]  D. W. Maclachlan,et al.  Modelling and prediction of the stress rupture behaviour of single crystal superalloys , 2001 .

[4]  P. J. Henderson,et al.  On the effects of heat treatments on the creep behaviour of a single crystal superalloy , 1986 .

[5]  D. W. Maclachlan,et al.  Anisotropic creep in CMSX-4 in orientations distant from 〈001〉 , 2000 .

[6]  Klaus-Jürgen Bathe,et al.  A hyperelastic‐based large strain elasto‐plastic constitutive formulation with combined isotropic‐kinematic hardening using the logarithmic stress and strain measures , 1990 .

[7]  D. W. Maclachlan,et al.  Fatigue behaviour and lifing of two single crystal superalloys , 2001 .

[8]  M. Mclean,et al.  On the threshold stress for dislocation creep in particle strengthened alloys , 1985 .

[9]  A. Argon,et al.  Creep resistance of CMSX-3 nickel base superalloy single crystals , 1992 .

[10]  Alan Needleman,et al.  An analysis of nonuniform and localized deformation in ductile single crystals , 1982 .

[11]  D. R. Hayhurst,et al.  Modelling of combined high-temperature creep and cyclic plasticity in components using continuum damage mechanics , 1992, Proceedings of the Royal Society of London. Series A: Mathematical and Physical Sciences.

[12]  John L. Bassani,et al.  Latent hardening in single crystals. II. Analytical characterization and predictions , 1991, Proceedings of the Royal Society of London. Series A: Mathematical and Physical Sciences.

[13]  R. Asaro,et al.  Micromechanics of Crystals and Polycrystals , 1983 .

[14]  D. W. Maclachlan,et al.  Modelling the uniaxial creep anisotropy of nickel base single crystal superalloys CMSX-4 and RR2000 at 1023 K using a slip system based finite element approach , 2002 .

[15]  D. M. Knowles,et al.  Constitutive modelling of anisotropic creep deformation in single crystal blade alloys SRR99 and CMSX-4 , 2001 .

[16]  D. M. Knowles,et al.  The effect of material behaviour on the analysis of single crystal turbine blades: Part I: Material model , 2002 .

[17]  Alan Needleman,et al.  Material rate dependence and localized deformation in crystalline solids , 1983 .

[18]  R. MacKay,et al.  The influence of orientation on the stress rupture properties of nickel-base superalloy single crystals , 1982 .

[19]  R. Ghosh,et al.  Creep deformation of single crystal superalloys—modelling the crystallographic anisotropy , 1990 .

[20]  A. Bertram,et al.  Damage modeling of the single crystal superalloy SRR99 under monotonous creep , 1998 .

[21]  Lei Chen,et al.  An assessment of three creep–fatigue life prediction methods for nickel‐based superalloy GH4049 , 2000 .

[22]  B. Fedelich.  A microstructure based constitutive model for the mechanical behavior at high temperatures of nickel-base single crystal superalloys , 1999 .

[23]  R. Reed,et al.  Creep of CMSX-4 superalloy single crystals: effects of rafting at high temperature , 1999 .

[24]  C. Laird,et al.  Latent hardening in single crystals - I. Theory and experiments , 1991, Proceedings of the Royal Society of London. Series A: Mathematical and Physical Sciences.

[25]  H. Brehm,et al.  Material model describing the orientation dependent creep behavior of single crystals based on dislocation densities of slip systems , 1999 .

[26]  N. O'Dowd,et al.  Finite element implementation of a generalised non-local rate-dependent crystallographic formulation for finite strains , 2001 .

[27]  R. Reed,et al.  On the primary creep of CMSX-4 superalloy single crystals , 2000 .

[28]  R. Reed,et al.  Creep of CMSX-4 superalloy single crystals: effects of misorientation and temperature , 1999 .

[29]  A. F. Giamei,et al.  Slip and climb processes in γ′ precipitation hardened nickel-base alloys , 1968 .

[30]  D. M. Knowles,et al.  Creep-behavior modeling of the single-crystal superalloy CMSX-4 , 2000 .