Digital Repository, FCP2003

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Crack Path Predictions on Modified C(T) Specimens under Variable Amplitude Loading
A. C. O. Miranda, M. A. Meggiolaro, T. P. Castro, L. F. Martha

Last modified: 2013-12-02

Abstract


A hybrid global-local methodology to predict fatigue crack propagationin 2D structures is extended to model crack retardation effects induced by variable-amplitude (VA) loading histories. First, finite element (FE) models are used at eachpropagation step to calculate the generally curved fatigue crack path. However, the FEapproach alone is not computationally efficient to predict crack growth rate, because itwould require time-consuming remeshing of the entire structure after each event in VAloading. Therefore, the crack path and their mixed-mode stress intensity factors are FEcalculated under constant-amplitude (CA) loading using fixed crack increments, requir-ing only relatively few remeshing steps. An analytical expression is then fitted to thecalculated KI values, which is used in a local-approach fatigue design program to pre-dict crack propagation lives under VA loading, considering load interaction effects suchas crack retardation or arrest after overloads. This methodology is experimentally vali-dated by fatigue crack growth tests on compact tension C(T) specimens, modified withholes positioned to attract or to deflect the fatigue cracks.

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