Publications

Results 26–50 of 74
Skip to search filters

Magnetic Smart Tags (MaST) for Arms Control and Treaty Verification

Langlois, Eric L.; Pillars, Jamin R.; Monson, Todd M.; Arrington, Christian L.; Finnegan, Patrick S.; St John, Christopher S.; Smartt, Heidi A.

The ability to track nuclear material is a challenge for resiliency of complex systems, e.g., harsh environments. RF tags, frequently used in national security applications, cannot be used for technological, operational, or safety reasons. Magnetic Smart Tags (MaST) is a novel tag technology based on magnetoelastic sensing that circumvents these issues. This technology is enabled by a new, cost-effective, batch manufacturing electrochemical deposition (ECD) process. This new advancement in fabrication enables multi-frequency tags capable of providing millions of possible codes for tag identification unlike existing theft deterrent tags that can convey only a single bit of information. Magnetostrictive 70% Co: 30% Fe was developed as the base alloy comprising the magnetoelastic resonator transduction element. Saturation magnetostriction, S , has been externally measured by the Naval Research Laboratory to be as high as 78 ppm. Description of a novel MEMS variable capacitive test structure is described for future measurements of this parameter.

More Details
TYPE SAND Report YEAR 2016
OSTIDOI

Fatigue stress concentration and notch sensitivity in nanocrystalline metals

Journal of Materials Research

Furnish, Timothy A.; Boyce, Brad B.; Sharon, John A.; O'Brien, Christopher J.; Clark, Blythe C.; Arrington, Christian L.; Pillars, Jamin R.

Recent studies have shown the potential for nanocrystalline metals to possess excellent fatigue resistance compared to their coarse-grained counterparts. Although the mechanical properties of nanocrystalline metals are believed to be particularly susceptible to material defects, a systematic study of the effects of geometric discontinuities on their fatigue performance has not yet been performed. In the present work, nanocrystalline Ni-40 wt%Fe containing both intrinsic and extrinsic defects were tested in tension-tension fatigue. The defects were found to dramatically reduce the fatigue resistance, which was attributed to the relatively high notch sensitivity in the nanocrystalline material. Microstructural analysis within the crack-initiation zones underneath the defects revealed cyclically-induced abnormal grain growth (AGG) as a predominant deformation and crack initiation mechanism during high-cycle fatigue. The onset of AGG and the ensuing fracture is likely accelerated by the stress concentrations, resulting in the reduced fatigue resistance compared to the relatively defect-free counterparts.

More Details
TYPE Journal Article YEAR 2016
ScopusOSTIDOI
Results 26–50 of 74
Results 26–50 of 74