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A master's thesis from Aalborg University
Book cover


Fatigue in cast metals: A generalized algorithm for multiaxial loading

Translated title

Udmattelse i støbemetal: En generaliseret algoritme for multiaksiel belastning

Term

4. term

Publication year

2014

Submitted on

Pages

110

Abstract

A fatigue crack growth algorithm for mul- tiaxial variable loading was proposed. Crack growth models Paris’ law, Forman eq. and NASGRO was evaluated relatively to each other. For the tested case studies Paris’ law was preferred. Test and validation of numerically deter- mined K I magnitdues. In both 2D and 3D the accuracy was within 2% of analytical solutions. In a case study of a plane problem, the crack propagation criterion of Richard was proven to be equal, to the maximum tan- gential stress criterion. Numerical mixed mode I+II crack direc- tion, showed fluactuating results, whereas the numerical mixed mode I+III showed good results. Finally, a case study of mode I+III crack growth, led to too conservative results. The deviations noticed in the crack direc- tion case studies, may haven been caused by inaccurate K II magnitudes. The fatigue crack growth deviations were expected to show too conservative crack growth rates, because plasticity induced crack closure was not implemented.