Georgy Shashurin

Numerical Life Estimation of Structure Components Subjected to Hydrogen Embrittlement and Cycling

Engineering models to estimate a life of structure components which are simultaneously subjected to aggressive hydrogen environment influence and cycling, substantially, use two different approaches to problem-solving, i.e. the influence of aggressive hydrogen environment on material and the fatigue. A developed engineering model to estimate the life of structure components assumes that either the influence of aggressive hydrogen environment, or the fatigue initiates a local fracture of structure component. The engineering model enables a calculating of a structure component life.

Engineering model of crack development in metals and alloys under corrosive hydrogenous media

The number of constructions with elements that are directly exposed to corrosive hydrogenous media is growing all over the world. This is why the problems of the design of engineering models of crack development in the elements of machines and constructions continuously affected by corrosive hydrogenous media are urgent. As compared to all other aspects of engineering modeling, special attention is being paid to approaches to the construction of kinetic energy charts of crack growth that are considered the main engineering tool of service life forecasting for elements that develop cracks. One such approach is described below.

Hydrogen Aggressive Media Impact on Cycling Durability of Structure Components

To develop modern CAE systems for durable and reliable structure components design, mathematical modeling of environmentally assisted metal cracking becomes very important. For structure components exploited in aggressive environment and under cyclic load, it is a problem of today. Besides, mathematical rule of damage accumulation of different causes (for instance, hydrogen media impact and cycling) is rarely used in CAE systems, but if such rule was used, crack propagation simulation considering several damage causes would be possible.Environmentally assisted metal cracking model (developed earlier by authors) is described in the paper. This model considers cyclic load and hydrogen embrittlement, the most important characteristics of which are hydrogen environmental concentration and load frequency respectively.The authors’ model successfully predicts effect, known from certain experimental data, that the greater is the frequency, the less hydrogen embrittlement affects fatigue cracks propagation and, vice-versa, that there are certain boundaries of cycling frequency for which embrittlement effect is comparably big.Such boundaries of frequency were numerically estimated by means of the presented model. Plots showing dependency of the component’s life on different defect and loading features are shown.

Cloud Applications Performance in Crack Growth Simulations of Pre-Hydrogenated Structure Components

The design of durable structure components requires durability analysis in CAE systems and cloud computations use is favorable for batch processing of multiple same-type calculation routines. To develop CAE durability modules analytical approach to different batch processing systems efficiency estimation is necessary. Such modules are intended for durability analysis of pre-hydrogenated and statically loaded structure components with initial defects. Durability estimate is defined as crack growth time elapsed from initial defect state to structure component fracture. Crack kinetics model had been used to simulate a fracture process, required for safe operation of a structure; crack length curves had been obtained and analyzed. The results were verified with the published experimental data on the subject at hand.The authors’ efficiency criterion was applied for performance analysis of the developed cloud application to find a subset of one modelling parameter in which the application is efficient being constrained in number of computational resources available and in the desirable level of performance.