FORMULATION OF POLYCRYSTAL PLASTICITY BAS ED ON THE FUZZY MODELING AND SIMULATION OF ROLLING TEXTURE EVOLUTION IN BCC METALS

A concept of fuzzy constraints for grain-interactions modelling in the large deformation polycrystal plasticity is presented. In accordance with this concept, the formulation for a method in the Taylor type fra mework of polycrystal plasticity has been done as a fuzzy mathematical programming problem (we call the fuzzy-Taylor problem), by introducin g the idea of ill-defined or ambiguous constraints of deformation impo sed on each grain in polycrystalline aggregate. This fuzzy-Taylor prob lem can be described as a multiobjective mathmatical-programming conta ining fuzzy numbers which are charactirized through a triangular type of membership function. A solution method of this problem is provided for calculating the rolling texture of bcc metals deformed by [111] pe ncil glide. The predicted rolling texture of bcc metals based on the f uzzy model was distinctly different from ones by the FC and RC models, and it exhibited the presence of the so-called gamma-fiber texture, i n which the {111} planes are parallel to the rolling plane.