Three-dimensional finite element simulation of a polycrystalline copper specimen

International audienceThe application of crystal plasticity in finite element codes provides a virtual copy of a real grain structure, including stress–strain state and slip system activity. This paper presents, first, finite element computations of an oxygen-free, high-conductivity copper multicrystal under monotonic tension. A series of polishing operations are used to reveal the real three-dimensional (3-D) microstructure, so that the mesh is a full 3-D mesh. A single crystal plasticity model is used to represent the elasto-plastic behavior for each of the approximately 100 grains. The results obtained with a full 3-D mesh and an extended 2-D mesh with columnar grains are compared in order to check the bias introduced by a simplified mesh generation. The paper goes on to compare the computational results to experimental data obtained by orientation image microscopy and local strain field measurements. Local strain and lattice rotation fields are shown. Finally, the numerical results for the slip system activity are analyzed

Growth and optical properties of Ag clusters deposited on poly(ethylene terephthalate)

The growth and concomitant evolution of the optical properties of Ag nano-clusters deposited on biaxially extruded poly(ethylene terephthalate) films is studied by reflectance difference spectroscopy. It is demonstrated by low energy ion scattering and simulated optical spectra that the clusters form a two-dimensional layer buried beneath the surface of the substrate. The experimental spectra are described by simulations in which different configurations of the host such as anisotropy, amorphization, and dilution are considered in an effective medium approach. The contribution of the anisotropic substrate is used to explain the resulting line shapes. We also discuss the role of the rate of change of the filling fraction with Ag coverage in the evolution of the spectra and the detection of the onset of coalescence by optical means