The general structure of multilevel models of polycrystalline inelastic deformation based on crystal plasticity and allow describing the evolution of materials internal structure is considered. It is assumed that crystallite inelastic deformation is realized by intragranular dislocation slipping and is accompanied by a lattice rotation. The paper focuses on the description of hardening laws formulated on the basis of physical analysis of defect structure elements interactions. To establish the connection between similar characteristics of different scale levels the consistency conditions of constitutive relations are used. Results of computational experiments on cyclic loading of representative volume of polycrystalline pure copper are obtained; it shows that proposed models allows to describe some effects of metals cyclic loading.

No abstract

No abstract

No abstract

The development of new technologies for thethermomechanical processing of metals and the improvement of the existing ones would be unattainable without the use of mathematical models. The physical and mechanical properties of alloys and the performance characteristics of the products made of these alloys are generally determined by the microstructure of materials. In real manufacturing processes, the deformation of metals and alloys occurs when they undergo complex (non-proportional) loading. Under these conditions, the formation of defect substructures, which do not happen at simple (proportional) loading, can take place. This is due to the occurrence of a great number of slip systems activated under loading along complex strain paths, which leads, for instance, to the more intense formation of barriers of different types, including barriers on split dislocations. In these processes, the formation and annihilation of dislocations proceed actively. In this paper, we present a three-level mathematical model that is based on an explicit description of the evolution dislocations density and the formation of dislocations barriers. The model is intended for the description of arbitrary complex loads with an emphasis on complex cyclic deformation.The model is composed of macrolevel (a representative macrovolume of the material that can be considered as an integration point in the finite-element modeling of real constructions), and mesolevel-1 (description of the mechanical response of a crystallite) and mesolevel-2 (description of the defect structure evolution in a crystallite) submodels. Using the model, we have performed a series of numerical experiments on simple and complex, monotonic and cyclic deformations of materials with different stacking fault energies, analyzed the evolution of defect densities, and analyzed the challenges of a relationship between the complexity of loading processes at a macrolevel and the activation of slip systems at low scale levels.