Three-dimensional simulation of fretting crack nucleation and growth

Fretting nucleation models and three-dimensional finite element analyses are used to compute the fretting fatigue life for metallic components. The models predict crack nucleation cycles and location(s). Discrete crack growth simulations provide stress intensity factor histories, with multiple, non-planar, three-dimensional cracks possible. The histories are input into crack growth rate model(s) to compute propagation cycles. The sum of fretting nucleation plus propagation cycles is the total life. Experimental fretting data, including crack nucleation location and cycles, and crack growth trajectory and propagation cycles, are used to validate the approach. Predictions for a realistic turbine blade/disk are comparable to field observations.

► Fretting fatigue nucleation models are combined with discrete crack growth.
► Standard finite elements used to simulate total fretting fatigue process.
► Predicted cycles and crack location from multiple nucleation models.
► Simulated discrete crack growth from nucleation site matches observed cracks.
► Simulation results indicate need for more fundamental micro-mechanics.