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.