Fatigue Crack Modeling and Analysis in Beams

Fatigue crack detection in aircraft engine bladed disk assemblies is slow, costly and imperfect, but developing an automated Structural Health Monitoring (SHM) system can help to reduce cost and improve detection probability. However, current methods for modeling nonlinear structural response are also too slow to generate suciently large data libraries for automation. In an eort to develop a faster method, fatigue cracks in beams are modeled by modifying the inputs to the structure rather than the structure model itself to produce a closed-form solution for the total response. With this approach, the time to produce data sets is reduced from days to seconds. Crack identication methods are then demonstrated using the data produced by the closed-form approach to correctly identify fatigue cracks in data generated by a more traditional bilinear model. Although the method investigated is orders of magnitude faster and can successfully identify fatigue cracks over certain regions, limitations are observed that require more investigation to resolve. Overall, the proposed method for modeling and identifying fatigue cracks in beams shows promise but will require more development before being used on more complicated structures such as bladed disks.