Plastic deformation and fracture of solids at the mesoscale level

Physical mesomechanics treats a solid under loading as a multilevel system where micro-, mesoand macrolevels are selfconsistent. The element base for the scale levels of plastic deformation of a solid is offered which allows to describe any kind of plastic flow as a combination of definite elements of this element base. Special attention is paid to description of fragmentation of a solid under loading as the main mechanism of plastic flow at the mesolevel. Fracture is the final stage of solid fragmentation when its scale changes from mesoto macrolevel.