Treffer: Assessment Approaches to Optimum Surface Hardening Parameters of Stress Concentrator-Bearing Structures.

The assessment of optimum surface hardening parameters of stress concentrator-bearing components is examined. Mechanics and mathematical model approaches were used to set the variational statement of the problem to find such a nonlocal (gradient) distribution of mechanical properties in the surface layers of components with stress concentrators that would improve the serviceability of structures as a whole. The functional was chosen as the optimality criterion that describes the contact strength of the structure and can assess the impact of strength parameters and stress concentrator characteristics on the product performance. The problem was solved with a free FEniCS finite element analysis package in Python. For a computer-processable software package, the algorithm is offered to evaluate the stress-strain state of a body with stress concentrators in contact interaction. The applied two-dimensional problem to assess the performance parameters of plasma-hardened locomotive tires with elliptic stress concentrators in view of their geometry is considered. A set of numerical experiments demonstrated that the geometric concentrator characteristics had a much greater impact on the product reliability than the size of such a defect. The concentrator radii ratio effect on the contact strength of a wheel tire was established. Elliptic concentrators with a major axis radii ratio greater than 40 were found to be most dangerous since just in the vicinity of their vertices, the stress state exhibits the worst performance parameters. Practical recommendations were advanced as regards the modified plasma-hardened layer depth to ensure adequate reliability of the rolling surfaces of railway wheels with an examined type of stress concentrators. [ABSTRACT FROM AUTHOR]

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