Effect of a Single Overload upon Fatigue Crack Growth in an Aluminum- Lithium Alloy
Abstract
The fundamental goal of this thesis was to investigate the effect of a single overload upon the behavior of fatigue crack growth in the aluminum- lithium alloy designated A1Li 2091. Specimens used in this study were compact tension (CT) specimens; crack growth was produced by a cyclic loading of constant load ration (0.1) and a constant maximum stress intensity factor, punctuated with periodic (single) overloads. Crack growth in the CT specimens was monitored by a variety of different instrumentations. Crack length was tracked using the electric potential (EP) method. Far-field measurements were taken via a clip gage (at the specimen mouth). Optical measurements, taken by travelling microscope, allowed for the correction of the EP crack length monitoring during the test if needed. In addition, load-displacement measurements were taken at a set of microhardness indents near the crack tip with a laser interferometric displacement gage (IDG). These near field measurements were compared to the closure measured by the clip gage, a far-field device. (KR)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1989
- Accession Number
- ADA216183
Entities
People
- Albert S. Perkins
Organizations
- Air Force Institute of Technology