The High Temperature Viscoplastic Fatigue Behavior of a Compact Tension Specimen Using the Bodner-Partom Flow Law.
Abstract
Few studies have been made concerning the effects of low cycle fatigue on the stress/strain field or the plastic zone size ahead of a crack tip in a high temperature environment. Experiments using a superalloy IN-100 at 732 C have shown crack growth during fatigue is slower than the growth rate during long periods of sustained load. These investigations also show that crack growth rates during hold periods after fatigue cycling are dependent on the cycle frequency. This study focuses on fatigue as it effects the changing stress field and plastic zone ahead of a crack tip. Finite element modeling was accomplished using an in-house computer program named VISCO, which was modified to incorporate load cycling. A compact tension specimen geometry was modeled using the Bodner-Partom viscoplastic constitutive equations to describe the material behavior. Results show that material behavior near a crack tip closely correlates to uniaxial material response data under stress controlled loading. During cyclic loading, the greatest plastic deformation near the crack tip occurs in the first load cycle. Computations show that IN-100 displays significant amounts of time dependent inelastic behavior.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1982
- Accession Number
- ADA124682
Entities
People
- James E. Keck
Organizations
- Air Force Institute of Technology