Measuring Micromechanical Behavior for Polycrystalline Materials under Cyclic Loading

Other Titles
Abstract

Understanding the crack initiation and propagation mechanisms of a polycrystalline material under cyclic loading remains a challenging problem. Complicated crystal stresses arising from single crystal anisotropy and complex grain and phase morphologies make the prediction of crack initiation and propagation at the grain scale difficult. In this work, oxygen free high conductivity copper specimens were cyclically loaded while high energy synchrotron x-ray diffraction experiments were performed to find the orientation dependent crystal stresses. From the x-ray diffraction data, the lattice strains and the peak widths were measured for several crystallographic planes oriented in many different directions at various points along a specimen?s life. Using the lattice strain measurements, crystal elastic strain distribution and stress distribution over orientation space were calculated. It was found that the evolution of the crystal stress distribution over orientation space with respect to specimen life is small but not negligible. The peak widths associated with the dislocation density and the distribution of elastic strain in a material also showed small changes with respect to specimen life indicating changes in the grain size scale. The contributions from changes in dislocation density and elastic strain distribution to the peak widths were decomposed and showed that while the elastic strain distribution over orientation space is complicated, its contribution to the peak width is small.

Journal / Series
Volume & Issue
Description
Sponsorship
Date Issued
2008-08-19T11:55:15Z
Publisher
Keywords
fatigue; synchrotron radiation; lattice strain; crystal stress; x-ray diffraction
Location
Effective Date
Expiration Date
Sector
Employer
Union
Union Local
NAICS
Number of Workers
Committee Chair
Committee Co-Chair
Committee Member
Degree Discipline
Degree Name
Degree Level
Related Version
Related DOI
Related To
Related Part
Based on Related Item
Has Other Format(s)
Part of Related Item
Related To
Related Publication(s)
Link(s) to Related Publication(s)
References
Link(s) to Reference(s)
Previously Published As
Government Document
ISBN
ISMN
ISSN
Other Identifiers
Rights
Rights URI
Types
dissertation or thesis
Accessibility Feature
Accessibility Hazard
Accessibility Summary
Link(s) to Catalog Record