3D fatigue crack propagation analysis of a helicopter component

In this paper, the analysis of fatigue crack propagation on the folding beams mounted on the rear fuselage of a helicopter is performed under complex flight and folding load spectra; a preliminary cumulative damage fatigue analysis is used to select the zone of the structure where cracking is most likely to occur. A damage tolerance analysis is then carried out in the selected zone using an FEM-based approach in conjunction with a Three-Dimensional (3D) automatic crack propagation algorithm developed by the authors. The submodelling technique is used to obtain accurate results in the assessment area with a limited increase in the amount of time required for calculations. The numerical approach is validated by the experimental results of full-scale fatigue tests on the rear fuselage of the helicopter.