Brittle Fracture Modeling for Steel Structures operated in the Extreme

Abstract

The Extreme here is an environment that contains conditions that are hard to survive even for steel structures due to extreme temperature, corrosion, inappropriate service and repair. So not only the mechanical properties and behavior of steel structures are important for structural integrity but also the phase transition processes, inhomogeneity and uncertainty factors. These problems are observed and discussed in the paper consisting of three main theoretical parts: the multiscale modeling approach for structural damage accumulation, the theory of low-temperature brittle-ductile transition for bcc steels, and uncertainty factors estimation concept. The applications describe the locomotive tire lifetime estimation at low temperature conditions, weld inhomogeneity calculation and bridge service life prediction. The modeling approach based on Kachanov-Rabotnov structural damage accumulation theory and stochastic crack growth modeling. Bayesian probability approach has been used for uncertainty factor estimation. The experimental research included the internal friction study of bcc steel, the mechanical tension and impact toughness testing for probes prepared from used in climatic condition of Central Yakutia locomotive tire steel, the low-cycling testing for welded steel probes, and microhardness estimation. The inhomogeneity of probes used for stress and strain state modeling. The microstructural study reveals the small cracks in heat affected zone so the size and distance between such defects used for stochastic modeling visualization of crack propagation and crack velocity estimation. The concept of service life estimation for welded steel bearing for bridges has been presented.