The calculation procedure for determining the plasticity of pre-deformed metals during their processing by pressure has been developed. The calculation procedure is based on a fracture model, which in turn is based on the tensor description of damage accumulation. With known mechanical characteristics, as well as with known plasticity diagrams, the fracture model makes it possible to evaluate the plasticity of pre-deformed bend for any kind of stress state. When manufacturing steeply curved branches using the pipe extrusion method, the procedure was tested. Verification of the mathematical model has shown a high level of its adequacy, and it can be used in assessing the plasticity of pre-deformed billet.
The problem of forecasting the durability of structures, buildings and constructions is one of the most urgent and important tasks in building sphere. In this paper, the authors propose a mathematical model of damage accumulation for the numerical simulation of the fatigue life of concrete. The results of numerical experiments with different levels of the applied load to the model are given, the fatigue characteristics of concrete material - Wohler curve - is built. On the basis of the developed method, the algorithm for research building designs using mathematical and physical modeling is formulated.
In this first part of a two-part paper, a mathematical model is presented for the prediction of spalling fatigue life in rolling bearings, which operate in contaminated lubricant, resulting in denting damage of the rolling surfaces. Five damage accumulation cases are treated: (I) Early or pre-existing damage; (II) Linear damage accumulation from constant lubricant contamination; (III) Accelerating damage from progressive wear; (IV) A combination of the above; and (V) Damage leveling off during stress cycling. Cases (I)-(III) lead to Weibull distributions of fatigue life, the others to more complex distributions. Experimental corroboration and application examples of the model are presented in Part II [16] of this paper.
A mathematical model of damage accumulation processes in structural steels is developed. This model considers degradation mechanisms that combine fatigue and creep of the material. The processes of viscoplastic deformation and damage accumulation in 08Х18Н10Т and 12Х18Н9 structural steels are numerically studied. The numerical results are compared with the data from full-scale experiments. The reliability of chosen defining equations describing combined effect of fatigue and creep mechanisms is confirmed.
An experimental methodology to characterise post-necking behaviour and quantify ductile damage accumulation in isotropic materials
