The three-dimensional strain map is useful to elucidate the relationships between microstructures and locally caused deformation and fracture. However, a robust tracking method, which enables error-free tracking in synchrotoron radiation computed tomography (SR-CT) images with more than ten-thousand microstructural features, is not currently available. In this study, a model sample was subjected to a tensile test and scanned by the SR-CT technique in order to develop a new tracking method. The developed tracking methods indicated a high tracking ratio and tracking success ratio of nearly 100% in a wide strain range, which included the assumed strain in a practical experiment. It was confirmed that tracking errors produce an incorrect strain distribution in three-dimensional strain mapping. This study verified the validity of the developed tracking method. The application of this method to high-resolution SR-CT images will make measurement and visualization of the strain distribution possible in three dimensions in bulk materials.
We present our plans for a MonteCarlo code simulating all possible combinations of (electromagnetic) interactions between colliding electron, positron, and both high-energy and laser photon beams, based on the ABEL code for beam-beam interaction. The implementation and first results for the laser-e-interaction are described. *Work supported by the Department of Energy contract DEAC-76SF00515 (SLAC)
Synchrotron X-ray microtomography has been used for the three-dimensional characterization of microstructure in the cell walls of aluminum foams. A combination of high-resolution phase contrast imaging technique and several application techniques has enabled the quantitative image analyses of microstructures as well as the assessment of their effects on deformation behaviors. The application techniques include local area tomography, microstructural gauging and in-situ observation using a specially designed material test rig. It has been clarified that ductile buckling of a cell wall occurs regardless of any of the microstructural factors in the case of a pure aluminum foam, while rather brittle fracture of a cell wall is induced by the existence of coarse micropores and their distribution independently of the intermetallic particles and the grain boundary in the case of aluminum foams alloyed with Zn and Mg. It has also been confirmed that coarse TiH 2 particles, which are a residual foaming agent added to alloy melts, remain intact during the deformation. When cooling rate during foaming is high, however, lower energy absorption might be attributable to the significant amount of residual TiH 2 particle and its inhomogeneous distribution. These tendencies are also confirmed by three-dimensional strain mapping by tracking internal microstructural features.
The status and initial performance of a simulation program CAIN for interaction region of linear colliders is described. The program is developed to be applicable for e + e − , e − e − , e − γ and γγ linear colliders. As an example of an application, simulation of a γγ collider option of NLC is reported.
The in situ high-resolution synchrotron x-ray computed microtomography has been applied to visualize and quantify the ductile fracture process of a notched Al alloy specimen. The three-dimensional (3D) investigation reveals that voids are nucleated, grow and coalesce more easily near the notch front and in the central region of the sample. These voids are mainly associated with Si particles in the eutectic (EU) phase. The 3D packing architecture of particles in the EU region, and the 3D morphology of α phase are also visualized. The feasibility of this technique highlights the potential of its application in the field of micromechanics-based fracture.
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