Macrocrack-Multiple Defect Interaction Considering Elastic, Plastic and Viscoplastic Effects
Abstract
A finite element investigation was conducted to analyze an axial tension specimen with collinear defects placed symmetrically about a center crack. The material modeled was IN-718, a nickel-based superalloy used in jet engines. The effects of crack/defect interaction were compared using elastic, elastic plastic, and viscoplastic constitutive models. A 2-D nonlinear finite element code called SNAP was used. This program has the capability to simulate crack growth and closure by releasing or closing nodes along the crack plane. Elastic stress intensity solutions were developed for two different finite width specimens. The stress intensity versus crack length plots compared well with infinite theory. Results reflect the defect can partially shield the crack from finite width effects. A critical spacing was also noted where the stress intensity of the crack exceeded the stress intensity for the combined length of the crack and defect. The defect has a prominent influence range equal to approximately one defect length for all constitutive models. The presence of a defect increases the magnitude of the crack opening and stress/strain fields in front of the crack tip.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1988
- Accession Number
- ADA203186
Entities
People
- Leroy K. Smith
Organizations
- Air Force Institute of Technology