Foundation of multilevel apploach to fracture modeling for materials with submicrostructure applicable for Arctic and Subarctic environment

Abstract

A short review of research on multiscale modeling of the fracture processes of heterogeneous materials with submicrostructures applicable to Arctic and Subarctic environments is presented. The results of solving a number of model problems, both in terms of macroscopic strength and main crack growth, and describing the accumulation of microscopic defects and hierarchical fracture processes by the mechanisms of formation, growth, and fusion of secondary and microcracks, and microscopic pores are provided. Thus, for the fracture process of samples of porous concrete modified with oil palm fruit fibers to improve its consumer qualities, a simulation of crack growth was conducted, which showed a decrease in the crack resistance of the material with increasing fiber content. A three-point bend test was used to evaluate the bending strength and modulus of elasticity, and the compressive strength and modulus of elasticity were determined. An increase in the fiber content led to a decrease in the compressive strength and modulus of elasticity. The fracture surface analysis revealed the mechanism of crack propagation through the coalescence of micropores. The basis of the modeling was an experimentally substantiated criterion for concentrated fractures during crack formation based on percolation theory. Macroscopic finite-element and stochastic modeling of fractures during the bending of a beam made of wood have also been carried out. For wooden structures, the peculiarity is the anisotropic behavior of the material in the loading direction. The structure of the Bilinga tree timber at the mesoscopic and microscale levels was considered, and a hierarchy of the spatial and temporal scales of the fracture process was constructed. The crack growth rates at different scales were determined and compared with macroscopic FE simulations. Another task was to determine the dependence of the crack growth rate in the soil, such as regolith, under the influence of an ultrasonic impactor. Stochastic modeling of the crack growth in the array of micropores revealed the crack growth rate dependence on the ultrasonic transmitter beater parameters and pulse amplitude.