Collective effects in a defect system of the structural element scale under deformation of a heterogeneous material with a regular structure

The accumulation of cracks (fibers break) under tensile deformation in a conventional model composite with a “small-scale” (on the order of 10 $\mu$m) structural element is studied by detecting acoustic emission signals in the linear location mode. The statistical analysis of the acoustic emission signal flow shows that an increase in correlation between breaks of fibers in one area is not fatal: the process is suddenly interrupted in this area and simultaneously initiated in the adjacent one. This process is governed solely by the relaxation mechanism of local stress redistribution. An ensemble of defects arising in one area produces a heterogeneity of a new scale. Because of the compatibility of strains, this qualitatively changes the structure of the object on a higher scale level. In the case of multiple micro- and mesocracking, the initiation of a main crack (macrofracture) depends on the stress field redistribution among higher scale areas compared with a typical structural element.