Fatigue Life Estimation of Damaged Structural Components Under Load SpectrumKatarina Maksimović Mirjana Đurić Miodrag Janković
This paper deals with fatigue behaviour of damaged aircraft structural components under cyclic loads of constant amplitudes and load spectrum. The primary attention of this investigation is to establish a computation procedure for the evaluation of the residual life of aircraft attachment lug type structural elements in the presence of initial cracks. The Strain Energy Density (SED) method is used in this investigation for a residual life estimation and a crack growth analysis. This method uses the low-cycle fatigue (LCF) properties of the material, which are also used for the lifetime evaluation until the occurrence of final failure. Therefore, the experimentally obtained dynamic properties of the material such as Forman`s constants are not required when this approach is concerned. The complete computation procedure for the crack propagation analysis using low-cycle fatigue material properties is illustrated with the cracked structural elements. To determine analytic expressions for stress intensity factors (SIF), singular finite elements are used. The results of a numerical simulations for crack propagation based on the strain density method have been compared with the author`s own experimental results. Key words: material fatigue, fatigue crack growth, cyclic load, low-cycle fatigue, finite elements, life time, aircraft construction.
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