Cyclic crystal plasticity analyses of stationary, microstructurally small surface cracks in ductile single phase polycrystals

This paper explores the effects of microstructural heterogeneity on the cyclic crack tip opening and sliding displacements for stationary, microstructurally small transgranular surface cracks in a single phase metallic polycrystal using planar double slip crystal plasticity computations. Crack tip displacements are examined under plane strain conditions for stationary cracks of different lengths relative to grain size as a function of the applied nominal strain amplitude for tension-compression and cyclic shear. Nominal strain amplitudes range from well below to slightly above the nominal cyclic yield strength for each type of loading condition. Results indicate the complex nature of the crack tip sliding and opening displacements as functions of nominal strain amplitude and orientation of the nearest neighbour grains, the influence of the free surface in promoting the cyclic opening displacement even for cracks in the first surface grain, the rather restricted limits of applicability of linear elastic fracture mechanics, and very interesting crack tip plasticity effects which include crack tip displacement ratcheting or progressive accumulation, even for completely reversed, proportional applied loading. Results are compared for cases with and without crack face friction.

[1]  Chingshen Li.  On the interaction among stage I short crack, slip band and grain boundary: a FEM analysis , 1990 .

[2]  K. P. Walker,et al.  The viscoplastic behavior of Hastelloy-X single crystal , 1993 .

[3]  Keisuke Tanaka,et al.  Propagation and non-propagation of small fatigue cracks , 1989 .

[4]  Y. Dafalias.  PLANAR DOUBLE-SLIP MICROMECHANICAL MODEL FOR POLYCRYSTAL PLASTICITY , 1993 .

[5]  Chingshen Li.  Vector CTD analysis for crystallographic crack growth , 1990 .

[6]  K. Gall,et al.  A Methodology for Predicting Variability in Microstructurally Short Fatigue Crack Growth Rates , 1997 .

[7]  M. Rashid,et al.  A constitutive algorithm for rate-dependent crystal plasticity , 1992 .

[8]  K. J. Miller,et al.  MODELLING SMALL FATIGUE CRACKS INTERACTING WITH GRAIN BOUNDARIES , 1991 .

[9]  A. Navarro,et al.  A MODEL FOR SHORT FATIGUE CRACK PROPAGATION WITH AN INTERPRETATION OF THE SHORT‐LONG CRACK TRANSITION , 1987 .

[10]  J. Lankford,et al.  Experimental Characterization of Fatigue Crack Tip Processes , 1985 .

[11]  On stable numerical integration methods of maximum time step , 1981 .

[12]  David L. McDowell,et al.  Microplasticity in HCF of Ti–6Al–4V , 2001 .

[13]  Florian A. Potra,et al.  Efficient line search algorithm for unconstrained optimization , 1995 .

[14]  K. J. Miller,et al.  THE EFFECTS OF MEAN AND ALTERNATING SHEAR STRESSES ON SHORT FATIGUE CRACK GROWTH RATES , 1992 .

[15]  Michael Ortiz,et al.  Computational modelling of single crystals , 1993 .

[16]  E. R. Rios,et al.  An alternative model of the blocking of dislocations at grain boundaries , 1988 .

[17]  L. Edwards,et al.  The effect of grain boundaries on the development of plastic deformation ahead of small fatigue cracks , 1992 .

[18]  David L. McDowell,et al.  A Finite Element Procedure of a Cyclic Thermoviscoplasticity Model for Solder and Copper Interconnects , 1998 .

[19]  P. Bowen,et al.  CRACK CLOSURE IN SMALL FATIGUE CRACKS—A COMPARISON OF FINITE ELEMENT PREDICTIONS WITH IN‐SITU SCANNING ELECTRON MICROSCOPE MEASUREMENTS , 1997 .

[20]  David L. McDowell,et al.  Polycrystal plasticity simulations of fretting fatigue , 2001 .