The Effect of High Altitude Environments on the Dislocation Structure Evolution During Fatigue Cracking of Legacy and Next Generation Aerospace Aluminum Alloys
Abstract
Next generation structural integrity management of airframe fatigue damage can increase accuracy and reduce over-conservatism by coupling the substantial progress in understanding and modeling mechanical loading spectra with similar efforts to capture the strong influence of an environmental spectrum. Recent efforts have quantitatively demonstrated orders of magnitude reductions in the fatigue crack growth rates (da/dN) for testing in high altitude environments (e.g. low temperature and low water vapor pressure (PH2O)) pertinent to high altitude flight. Critically, despite a constant exposure parameter (PH2O/frequency), differences in da/dN are observed between tests at 23 degrees C and low temperature environments (below -30 degrees C). The main objective of this project is to gain an understanding of the factors governing the environmental cracking behavior via characterization of the dislocation structure in the near crack wake regime of an aerospace Al alloy (7075-T651) at different environmental conditions.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 18, 2019
- Accession Number
- AD1104804
Entities
People
- James Burns
Organizations
- University of Virginia