Hybrid Process Uses Electromagnetic Force to Mold Aluminum Auto Parts
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tents into a sarcophagus of solid granite. Beyond it lies the zone of metamorphosed rock, and beyond that, a final zone where hydration reactions will add a final barrier by plugging rock fractures. These zones constitute a multiple “near field” barrier, whereas the 4-km burial depth—much greater than that envisaged for conventional nuclear repository—constitutes the “far field” barrier. Gibbs said that rocks are much more uniform at such great depth, liberating planners from the dictates of shallow geology, and thus greatly increases the choice of available sites. He said also that any intra-rock water present at these depths is stable, has been there for millions of years, and will not return to surface so long as
the hole is adequately back-filled and sealed. Leakage of radionuclides from the sarcophagus would probably not matter since the waters present at such depths have not moved for millions of years. Very deep disposal of this sort also increases the likelihood of the containment surviving earthquakes.
Hybrid Process Uses Electromagnetic Force to Mold Aluminum Auto Parts Glenn S. Daehn, professor of materials science and engineering at Ohio State University, and his colleagues at Ohio State and General Motors developed a process that combines traditional metal
stamping with electromagnetic forming. In this hybrid technique, a tool stamps out the general shape of a part, and electromagnetic pulses help form details. As Vincent J. Vohnout, a postdoctoral researcher in materials science and engineering, reported at the International Conference on Technology of Plasticity in Nuremberg, to keep the aluminum sheet from tearing, the researchers softened the shape of the tool, replacing sharp corners with gradual curves, and stamped the general shape of the part. They then turned to electromagnetic forming, and like-charged metal coils repel the metal into a mold. The researchers placed coils behind only the unfinished spots of the panel, and used electromagnetic force to
Biomechanics Meeting Presents Materials-Related Topics Scientists at the 23rd Annual Meeting of the American Society of Biomechanics, held in October 1999 in Pittsburgh, presented materials-related issues involving polymers, surface treatment, and bone prostheses. In one presentation, by simulating the natural load on human thigh bones, scientists Michael H. Santare and Suresh G. Advani of the University of Delaware proposed a design for an artificial hip that would reduce stress-shielding and prevent bone atrophy. After they modeled the function of a healthy hip, Santare and Advani compared their findings with an analysis of the stress patterns produced by a conventional artificial hip and by the design pioneered by E. Munting and M. Verhelpen in 1995 in which a much shorter rod than previously used, attached to the top of the thigh by several small bolts, was inserted through the exterior side of the bone. Santare and Advani’s resulting design greatly reduced the prosthetic rod, which seems to be responsible for much of the rigidity and alt
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