Load sharing in two-phase alloys is investigated by means of finite element simulations of polycrystalline aggregates subjected to uni-axial compression. Attention is focused on the redistribution of stress as the overall load level increases and the material progresses from a purely elastic state to eventual yielding of both phases. Virtual specimens having two phases, one of iron and the other of copper, were created and subjected to compression. The lattice (elastic) strains, which are directly proportional to the stress, were examined over the course of the compression test for a system having equal volume fractions of each phase. Comparisons were made first with measurements by neutron diffraction to confirm that the simulated strains followed the observed behavior. The computed lattice strain tensors then were examined in terms of the changes in their principal directions as the overall load increased. The redirection of the stress signals a change in the relative stiffnesses of the phases, from which follows a repartitioning of stress between the phases.
Bibliographical noteFunding Information:
This research was sponsored by Air Force Office of Scientific Research (AFOSR) under University Grant #F49620-02-1-0047. Parallel finite element calculations were performed at the Cornell Theory Center. The authors wish to thank Professor Matthew Miller for useful discussions on the experiments, and Mr. Joel Bernier for providing the diffraction experimental data. Diffraction experiments were performed on the Spectrometer for Materials Research at Temperature and Stress (SMARTS) facility at the Los Alamos Neutron Science Center (LANSCE) with the assistance of Dr. Donald Brown. Iron–copper alloys from which specimens were fabricated were provided by Professor Christian Hartig, Department of Materials Science and Technology, Technical University Hamburg-Harburg. The authors also would like to acknowledge Dr. Martin Mataya at Los Alamos Laboratory for supplying the macroscopic stress–strain data.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering