Abstract: For combined HCF/LCF loading, whose stress history is simplified so that it consists of one LCF stress block with a number of cycles equal to the number of start-up in-service operations and one HCF stress block with all HCF cycles summed-up, we derived the closed form expression for estimating both the crack initiation life and the crack propagation life at combined HCF/LCF loading. As an example of use, Smith and Haigh diagrams were obtained for titanium alloy (Ti-6Al-4V) components, which enable to estimate the fatigue strength for the designed fatigue life, known load ratio and certain number of HCF cycles per one combined stress block.Keywords: machine elements, fatigue, service life prediction, crack initiation, crack growth, stress historyPublished in DKUM: 01.06.2012; Views: 2585; Downloads: 51 Link to full text
Abstract: The paper deals with the research on the crack growth in a bolt connection of a lug for crane counter weight bars. Counter weight bars are structural elements subjected to very heavy loads and therefore need special attention. The main purpose of this research is to determine the number of load cycles required for a crack to propagate from initial to criticakl crack length, whenthe final failure can be expected to occur. All required material parameters and experimental results were determined in our previous research. The influence of the initial crack siye upon the remaining life of the lug is reserched numericallu by means of FE analysis and analytically by use of the corrected analystical model.Keywords: fracture mechanics, cyclic loading, fatigue crack growth, service life prediction, numerical analysis, bolt connectionPublished in DKUM: 31.05.2012; Views: 2501; Downloads: 125 Link to full text
