Algorithms for numerical simulation of structures deformation and fracture within relations of damaged medium mechanics

The article describes the algorithms implemented in computational complex UPAKS (VC UPAKS) which allow studying the start and development of fatigue cracks under low-cycle thermopower loadings by a direct numerical simulation based on the finite element method within the time acceptable for engineering computations. The studies are carried out in the framework of damaged medium mechanics and use the hypotheses on the multi-stage nature of damage development in the process of material failure. The paper presents an algorithm of predicting deformation processes and damage accumulation in structural elements at low-cycle thermopower loadings, which combines the possibility to have a detailed description of deformation and damage accumulation in the early fracture stages while minimizing the number of computations in the numerical modeling of these processes on the basis of FEM.To investigate the third stage of fracture process, the authors have developed an algorithm for crack propagation modeling in structural elements on the basis of results of the process simulation in the first two stages without changing the initial topology of finite elements of the studied structure. The results of simulation of elastic-plastic fracture of the experimental sample with a concentrator under a plain bending which have been made using VC UPAKS are given. The comparison of numerical results with experiments has shown their good compliance which proves that the efficiency of the proposed algorithm. By using the simulation examples/cases of low-cycle fracture of a cylindrical recessedsample the authors verified the software that implements the proposed algorithms as part of VC UPAKS software. It proved that they can be effectively used to simulate low-cycle fracture processes of structure elements.