Numerical approach for determining the endurance limit of autofrettaged components taking into account plasticity and temperature effects

摘要

The study offers some new insights into the role of the temperature effects on the residual stress redistribution and its impact on the endurance limit determined by numerical fracture mechanical methods. The influence of elevated temperature, typical for operating fuel injection systems of Diesel engines, on the fatigue strength of such systems is the subject of the research project. The investigation covered components, whose original durability has been increased by the mechanical procedure of autofrettage (unique mechanical overload). New investigations serve basically for the study of fatigue behaviour of components at elevated operating temperatures up to 180°C, which have influence on the residual stresses redistribution over many load steps. The numerical approach consists of two main tasks, the description of the material properties for the elastic-plastic material models and the application of nonlinear fracture mechanics based on the FE-analysis. Finally, the presented simulation results based on the finite element model and the fatigue crack growth life will be compared with experimentally determined data by testing autofrettaged cross-bore specimens.