2.2 Aircraft damage tolerant repair methodology for different repair techniques
To evaluate and compare the outcome of the repair techniques, we carry out the BRSW workflow described above for several scenarios, i.e., un-repaired, live-crack repair, and crack removal repairs, as shown in Figure 3. The methodology starts with crack initiation estimation from either an undamaged wing structure or repaired wing structure with crack removal based on Fatigue Mechanics theory [21] and literatures [22], [23]. Fatigue crack propagation prediction with and without repairs on damaged wing structures employs Fracture Mechanics tools in Ansys software, where fracture parameters such as stress intensity factors are evaluated through SMART [19] and XFEM [18] FEA technologies, which in turn drive and quantify fatigue crack growth. The obtained relationship between crack growth and load cycles allows the service life estimation and repair decision guidance. As the damaged structure takes more service cycles leading to further fatigue damage, the FEA process automatically advances the crack growth and updates the further weakened structure integrity, accurately capturing the complex cohesion between damage state and remaining service life.