Residual Stresses and Elastic Properties in Polycrystalline Materials
Abstract
The primary objective of this research program was to assess and develop the use of high-precision ultrasonic interferometry as a means of evaluating the internal residual stresses in polycrystalline materials. The method which was pursued involved the comparison of the elastic properties of the polycrystalline solid with those inferred for the stress-free aggregate from single-crystal data used in conjunction with and appropriate theoretical averaging scheme. Another approach, based on residual stress-induced transverse isotropy, also was evaluated. A primary problem with all acoustic approaches is associated with effects arising from microstructural characteristics. In the present study, accurate microstructure characterization and theoretical models were utilized to account for these effects. Residual stress evaluation by the photoelastic method was employed also as an independent means of comparison. Work in this study was limited to MgAl2O4 spinel, which was available in high- quality single-crystal specimens and polycrystalline blanks. Extensive sets of elastic property data were obtained as functions of both temperature and pressure for numerous specimens of single-crystal and polycrystalline spinel. Our single-crystal second-order elastic constant results for stoichiometric spinel compared favorably with those from previous studies. The higher-order property results, particularly with respect to temperature, are new and provide useful insight relevant to the high P,T equation of state.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 16, 1985
- Accession Number
- ADA161446
Entities
People
- E. K. Graham
- R. C. Bradt
Organizations
- Pennsylvania State University