A discrete-element based model of elastic-plastic materials with non-ideal plasticity and with an account of both cohesive and adhesive interactions inside the material is developed and verified. Based on this model, a detailed study of factors controlling the modes of adhesive wear is performed. Depending on the material and loading parameters, we observed three main modes of wear: slipping, plastic grinding, cleavage, and breakaway. We find that occurrence of a particular mode is determined by the combination of two dimensionless material parameters: (1) the ratio of the adhesive stress to the pure shear strength of the material, and (2) sensitivity parameter of material shear strength to local pressure. the case study map of asperity wear modes in the space of these parameters has been constructed. Results of this study further develop the findings of the widely discussed studies by the groups of J.-f. Molinari and L. pastewka.Adhesive wear is a complex, multiscale and still poorly understood phenomenon 1-3 . This kind of wear occurs in contact pairs where materials of interacting bodies are characterized by equal or similar values of hardness with the possible transfer of material from one surface to the opposite one. Since the publication of Rabinowicz from 1958 4 , it is known that adhesive wear is controlled by the relation of material parameters including elastic modulus, hardness and specific surface energy 4,5 . In a series of recent works by Aghababaei, Molinari et al., it was shown that adhesive wear may develop in two ways: 1) formation and evolution (growth or fragmentation) of wear particles or 2) plastic deformation of micro contacts accompanied by smoothing of asperities 6,7 . These studies together with works by other research groups 8-11 created a solid basis for a theoretical understanding of wear modes and opened possibilities for a new interpretation of classical concepts. In particular, the adhesive wear mode criterion by Rabinowicz was critically revised and details were disclosed of how the wear process occurs in both regimes of debris formation and plastic smoothing.The above mentioned fundamental results revealing the features of asperity fracture and wear were obtained using pseudo molecular dynamics (MD) simulation at the mesoscale, so the question remained whether these conclusions are universal and applicable to real materials. A particular problem of meso MD models consists in the difficulty of separating the plastic and adhesive properties of material as in meso molecular dynamics both of them are determined by the same interaction potential. On the mesoscopic scale, it may be necessary, firstly, to decouple strength from adhesion parameters of the material and, secondly to take into account more complex material properties such as yield stress and strain hardening, both strongly dependent on features of internal structure at lower scales (grain structure, grain boundaries, inclusions of other phases, etc.). This substantiates the need for a detailed theoretical analysis of wear r...

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The paper is devoted to the development of the formalism of the computational method of discrete elements (DEM) for describing the mechanical behavior of consolidated viscoelastic materials. We considered an advanced implementation of DEM, namely, the method of movable cellular automata (MCA). A feature of this implementation of DEM is the use of a generalized many-body formulation of the relations for the forces of element-element interaction. 3D numerical models of viscoelastic material with a spectrum of relaxation times (Kelvin and Maxwell models, the standard model of elastomers, and others) were developed within the formalism of MCA. The correctness of the developed discrete element formalism and its applicability for modeling the processes of deformation and fracture of viscoelastic materials under dynamic loading are shown using the standard model of elastomers as an example. The relevance of the results is determined by the prospects for the further development of DEM and its application to study and predict the mechanical response of viscoelastic materials of various nature under dynamic loading including contact problems.

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