FATIGUE CRACK GROWTH BEHAVIOUR UNDER MIXED-MODE LOADING

L. P. Borrego  F. V. Antunes  J. D. Costa  J. M. Ferreira     

Anales de la Mecánica de la Fractura, nº 22 . 2005 . Pág. -
Ver (.pdf): 62

Resumen: Fatigue crack propagation tests in compact mixed-mode specimens were carried out for several stress intensity ratios of mode I and mode II, KI/KII, in AlMgSi1-T6 aluminium alloy with 3 mm thickness. The tests were performed in a standard servo-hydraulic machine. A linkage system was developed in order to permit the variation of the KI/KII ratio by changing the loading angle. Crack closure loads were obtained through the compliance technique. A finite element analysis was also done in order to obtain the KI and KII values for the different loading angles. Crack closure increases under mixed-mode loading conditions in comparison to mode-I loading due the friction between the crack tip surfaces. Moreover, the crack closure level increases with the KI/KII ratio decrease. Correlations of the equivalent values of the effective stress intensity factor with the crack growth rates are also performed.

LocalizaciónAlmagro

Departamento de Engenharia Mecânica, Instituto Superior de Engenharia de Coimbra, Instituto Politécnico de Coimbra, Portugal.
Departamento de Engenharia Mecânica, Faculdade de Ciências e Tecnologia da Universidade de Coimbra, Portugal.
Departamento de Engenharia Mecânica, Faculdade de Ciências e Tecnologia da Universidade de Coimbra, Portugal.
Departamento de Engenharia Mecânica, Faculdade de Ciências e Tecnologia da Universidade de Coimbra, Portugal.