Creep Behavior of Thin Laminates of Iron Cobalt Alloys for Use in Switched Reluctance Motors and Generators.
Abstract
The United States Air Force is in the process of developing magnetic bearings as well as an aircraft Integrated Power Unit and an Internal Starter/Generator for main propulsion engines. These efforts are the driving force behind a new emphasis to develop magnetic materials with strengths in excess of 80 ksi up to about 1000 degrees F. Hiperco Alloy 50HS is one of the leading candidates for application and is the focus of this effort. Tensile testing provided stress versus strain behaviors that clearly indicated: a yield point, Luders elongation, the Portevin-LeChatelier effect at elevated temperatures, and, most often a section of homogeneous deformation that concluded with necking and fracture. Creep testing indicated two distinct types of behavior. The first was a traditional response with primary, secondary, and tertiary stages, while the second type could be characterized by an abrupt increase in steady-state strain rate. Analyses of the mechanical behavior included double linear regression of empirically modeled data, scanning electron microscopy, isochronous stress-strain relations, and constant strain rate testing. Also, elastic and creep deformation analyses were done, which incorporated material property data and material constants determined along with stress and displacement profiles for a specific design configuration.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1999
- Accession Number
- ADA366938
Entities
People
- Richard T. Fingers
Organizations
- Air Force Research Laboratory