Unification of Calculation Methods and Tests for Strength, Resource, and Crack Resistance

摘要

In this paper, we show that the solution of the problems on strength, resource, and crack resistance for all objects of the machine-building complex is largely reduced to the scientifically substantiated determination of the acceptable design parameters of the resource and the retention of the stress and deformation levels of the bearing elements of the objects in question within the permissible limits. This requirement applies to the main operational design parameters: durability over the number of cycles and time, defect size, temperature, and deformation rate. Supported by the necessary computational and experimental information, the state equations corresponding to the indicated cases allow evaluating the conditions of reaching the limiting states of the objects under consideration by the value of the reserves. Traditional methods of designing, manufacturing, and operating equipment based on the determined criteria of static, long-term, cyclic, dynamic, and temperature strength, on standard characteristics of the mechanical properties of structural materials, on analysis of nominal and ultimate stress states of load-bearing structures, and on the introduction of stress reserves, deformations, and resource are considered using the described approach. The necessity of the transition in the calculations of strength, resource, and crack resistance to a generalized analysis of the fracture criteria based on multivariate calculation and experimental methods for determining reserves is emphasized. According to the above, the solution of the fundamental problems of analysis and ensuring the regular and emergency operation of objects of the technosphere according to the proposed approaches is based on their direct quantitative relation with the results of solving problems of constructing state equations, solving boundary value problems, and formulating criteria for limiting states with an assessment of safety margin, resource, and crack resistance. In this case, a complex and interconnected system of deformation curves and fracture curves is constructed based on the characteristics of the mechanical properties of materials included in the estimates of stress-strain and limiting states. Linear (elastic) and nonlinear (elastoplastic) approaches to construct the calculated kinetic dependences characterizing in general formation and development of damage and fracture zones that determine the change in reserves are analyzed as the main ones.