A novel fracture mechanics approach has been used to predict crack propagation lives in gas turbine engine blades subjected to vibratory high cycle fatigue (HCF). The vibratory loading included both a resonant mode and a nonresonant mode, with one blade subjected to only the nonresonant mode and another blade to both modes. A life prediction algorithm was utilized to predict HCF propagation lives for each case. The life prediction system incorporates a boundary integral element (BIE) derived hybrid stress intensity solution, which accounts for the transition from a surface crack to corner crack to edge crack. It also includes a derivation of threshold crack length from threshold stress intensity factors to give crack size limits for no propagation. The stress intensity solution was calibrated for crack aspect ratios measured directly from the fracture surfaces. The model demonstrates the ability to correlate predicted missions to failure with values deduced from fractographic analysis. This analysis helps to validate the use of fracture mechanics approaches for assessing damage tolerance in gas turbine engine components subjected to combined steady and vibratory stresses.

Cunningham, S. E., DeLuca, D. P., and Haake, F. K., 1993, Crack Growth and Life Prediction in Single Crystal Nickel Superalloys, Vol. 1, P&W Internal Report FR-22593-1, Mar.
Cunningham, S. E., DeLuca, D. P., Hindle, E. H., III, Sheldon, J. W., and Haake, F. K., 1994, Crack Growth and Life Prediction in Single Crystal Nickel Superalloys, Vol. 11, P&W Internal Report, Mar.
Cunningham, S. E., and DeLuca, D. P., 1995, “Assessing Crack Growth Behavior Under Continuous Temperature Gradients,” Second Symposium on Thermo Mechanical Fatigue Behavior of Materials, M. J. Verrilli and M. G. Castelli, eds., American Society for Testing and Materials, Philadelphia, submitted for publication.
DeLuca, D. P., and Cowles, B. A., 1989, in: Hydrogen Effects on Material Behavior, N. R. Moody and A. W. Thompson, eds., Warrendale, PA, pp. 603–613.
, and
L. J.
, “
The Unusual Near-Threshold FCG Behavior of a Single Crystal Superalloy and the Resolved Shear Stress as the Crack Driving Force
Engineering Fracture Mechanics
, Vol.
, pp.
This content is only available via PDF.
You do not currently have access to this content.