Application of two creep fatigue life models for the prediction of elevated temperature crack initiation of a nickel base alloyCyclic Damage Accumulation (CDA) and Total Strain-Strain Range Partitioning (TS-SRP) models for predicting the creep-fatigue crack initiation life of high temperature alloys are presented. The models differ in their fundamental assumptions regarding the controlling parameters for fatigue crack initiation and in the amount of data required to determine model constants. The CDA model represents a ductility exhaustion approach and uses stress quantities to calculate the cyclic fatigue damage. The TS-SRP model is based on the use of total mechanical strain and earlier concepts of the Strain Range Partitioning Method. Both models were applied to a well controlled fatigue data set at a high temperature nickel base alloy, B1900 + Hf, tested at 1600 F and 1800 F. The tests were divided into a baseline data set required to determine model constants and a verification data set for evaluation of the predictive capability of the models. Both models correlated the baseline data set to within factors of two in life, and predicted the verification data set to within a factor of three or better. In addition, sample calculations to demonstrate the application of each model and discusions of the predictive capabilities and areas requiring further development are presented.
Document ID
19850061828
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Moreno, V. (Pratt and Whitney Aircraft Group East Hartford, CT, United States)
Nissley, D. M. (United Technologies Corp. Pratt and Whitney Group, East Hartford, CT, United States)
Halford, G. R. (Pratt and Whitney Aircraft Group East Hartford, CT, United States)
Saltsman, J. F. (NASA Lewis Research Center Cleveland, OH, United States)