Crack propagation influenced by variable loads that are lower than the loading level of quasistatic fracture is called material fatigue. Fatigue is causing the largest number of damages and failures of parts and structures during exploitation. In a number of cases damages can be assigned to the material state, but a lot of damages are consequence of a poor constructive design and more often bad welded joints. Accordingly, fatigue tendency of a part of machine, structure or welded joint, does not depend merely on fatigue strength of the material used for a part fabrication but its geometry as well. Therefore, when increasing a machine or structure fatigue endurance is set as a task, it should be taken into consideration that mere selection of more durable material for parts fabrication is not sufficient and often is inefficient, and new constructive solutions presents better alternative. Defects in metals and various forms of stress concentration (notches, grooves, holes welded and mechanical joints) in elements can’t be avoided. Therefore, period until fatigue crack initiates, Ni, can be neglected, from angle of total fatigue life until crack appearance, Nu. Considering that macroscopic crack growth rate can’t be affected by structural alternation, it remains to determine the crack growth rate in laboratory conditions for the given material of specimen or element, and after the crack size determination during occasional inspection to estimate the remaining life of machine part or structure. Theses of linear elastic fracture mechanics provide the possibility for this estimation.
Тематска област:
Механика и конструкције
Уводни рад:
Да
Датум:
29.12.2010.
Бр. отварања:
873
11th International Conference on Accomplishments in Mechanical and Industrial Engineering
Датотека уз рад
(5.86 MB)
