A New Approach for Investigating Crystal Stresses that Drive the Initiation of Fatigue-Induced Defects in Structural Alloys
Abstract
We have developed an approach to investigate crystals stresses during cyclic load by coordinating experiments and simulations at the size scale where fatigue induced defects initiate. Our efforts provided new understanding of the stress evolution during cyclic loading through a complementary process between the experimental measurement of lattice strain and the simulation results. The comparison of the experimental and the simulated lattice data culminated in a novel picture of how the stress evolves at the crystal scale. Specifically, using the crystal-based elastoplastic finite element model, we found that for different levels of the single crystal elastic anisotropy, different sets of crystal {hkl}s within a FCC polycrystalline sample evolve differently through the elastic-plastic transition under monotonic tension loading. It is the strength-to-stiffness ratio of these {hkl}s that determines the crystal lattice strain and yield behavior for different values of the single crystal elastic anisotropic ratio. The single crystal elastic anisotropy also causes the hysteresis loops under fully-reversed cyclic loading to contract preferentially. For a given average grain size and crystallographic texture, an experimental method for measuring a representative volume element (RVE) in orientation.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 31, 2008
- Accession Number
- ADA500764
Entities
People
- Paul R. Dawson
Organizations
- Cornell University