The literature review on the effects of overloading on fatigue crack initiation and growth will be assessing the required technical and theoretical background.
The effect of overloading cycles on high cycle fatigue (HCF) crack growth rate is to be investigated. Exposure to overload can enhance or slow subsequent HCF crack growth rate depending on the amount of overload and the material. The results are to be compared to the cumulative damage rules commonly used in fatigue assessment. Modelling, numerical analysis and/or microscopic examination are to be conducted in order to identify both the strengthening and weakening mechanisms.
1.1 Different effects on fatigue failures
Several theoretical factors have been initiated for explaining the fatigue failure of different materials. Crack propagations after subjecting to overloads and other factors are visibly notable. Overloads are the main notable effect on fatigue failure with two main categories depending on it namely tensile overload, under loads and band overloads. Followings are the main mechanisms which will help for further propagation of cracks [1].
â€¢ Residual stresses
â€¢ Deflection of cracks
â€¢ Crack closure states
â€¢ Strain hardening
â€¢ Plastic blunting procedure/re-sharpening
The cracks will be propagating under different conditions stated above and they can be experimented under controlled experiments and procedures to monitor the status of cracks.
1.2 Factors and mechanisms
Developing a crack growth is simply a little harder and some prediction models can be recognized by initiating transient effects which have been under the effect of single overload and mechanisms such as crack closure, residual stress, crack deflection, plastic blunting/resharpening and strain hardening. Among these, two have been identified as the most critical examination and application on creating fatigue failure.
1.2.1 Single overloading
Overloading is the basic crack propagation cause which will initiate fatigue failure. Air craft modeling
and aviation technology vastly consider about overloading and its effects on fatigue failure. Loading components imposed on structural components will be mainly variable amplitude loading. A set of treatment should be considered for negating the effect of such loading. Some of them are crack tip stress analysis, an integrated consideration of flight load spectra, component load spectra and law related to crack growth

4-1 Given that: force F, a, Q, 0; (1)Determine the moment of F abo...