Multi-scale Corrosion Fatigue Model And The Method Of Software Integration

A variety of structures subjected to cyclic loading corrosion fatigue failure may occur in engineering application, which often results in a major accident and heavy losses. Therefore, a corrosion fatigue probabilistic model based on chemical-mechanical mechanism was necessary for corrosion fatigue life prediction in industry field. A multi-scale probabilistic corrosion fatigue model that composed of four stages:pitting nucleation, pit growth, short crack growth, and long crack growth was proposed in this thesis. Then, the model was verified by experimental data, the Monte Carlo simulation was used for reliability analysis. Finally, based on the representative model the corrosion fatigue life prediction software with a visual interface was developed. An idea to analyze corrosion fatigue by incorporating the research on corrosion fatigue mechanism, total life model, probabilistic reliability analysis and the method of software integration was proposed in the thesis, and it also supports a practical analysis method for corrosion fatigue life cycle management and safe life design of components. The main research contents and conclusions are listed as follows:(1) Considered the chemical-mechanical interaction of corrosion fatigue, the critical size of pit to short crack, short crack to long crack was constant and determined by the system, short crack to long crack were included in the crack propagation, a multi-scale model that contains all stages of corrosion fatigue was established.(2) The established corrosion fatigue life model was verified by experimental data from classic literature.2024-T3aluminum alloy,12Gr Turbine blade steel, LY12aluminum alloy in the literature was verified and discussed, and the model predictions showed great agreement with experimental results.(3) Based on the probability of damage tolerance method and fracture mechanics theory a probabilistic model of corrosion fatigue was established, and the reliability was analyzed with the Monte Carlo simulation, it was implemented with2024-T3aluminum alloy.(4) Based on classical corrosion fatigue models, the corrosion fatigue life prediction software (CFCrack) was developed. It contained some different environmental systems such as solution-metal, gas-metal, and included22kinds of specific environment system (Cl or S corrosion, etc.), and could be effectively used for life predictions.