Multiaxial Low Cyclic Fatigue Damage Model for Single Crystal Nickel-Based Supe ralloy
Ding Zhiping(1),Chen Jiping(1),Yin Zeyong(2)
(1 Zhuzhou Institute of Technology，Zhuzhou，412008, China) (2 China Aviation Power Plant Research Institute, Zhuzhou, 412002,China)

Abstract: According to the continuum damage mechanics theory, being known as at hermodynamics generalized force, a strain energy release ratio is employed in describing fatigue damage course of orthotropic materials. The nonlinear effec t of crystal orientation of single crystal Nickel-based superalloys on fatigue damage is taken into account by introducing an orientation function. An anisotro picfatigue damage model is proposed, the coefficients appearing in the model can be obtained by fitting fatigue test data with multianalysis of linear regression. The strain triaxiality factor for single crystal superalloys containing three elastic constants was deduced, where the correlation of crystalloid orientation of material performance as well as mutual action between tension stress are mani fested. The correlation coincides with experiments well while the model is used to predict the stress controlled low cycle fatigue life of single crystal Nickel-based superalloy CMSX2 under fully-reversed tension-torsion loads, and the all data fall into the factor of 2.2 scatter band.
Keywords: single crystal superalloy, orthotropy, low cyclic fatigue, damage model.