Publications

Thermal mechanical stresses of glass-ceramic to stainless steel (GCtSS) seals are analyzed using finite element modeling over a temperature cycle from a set temperature (Tset) 500°C to −55°C, and then back to 600°C. Two glass-ceramics having an identical coefficient of thermal expansion (CTE) at ~16 ppm/°C but very different linearity of thermal strains, designated as near-linear NL16 and step-like SL16, were formed from the same parent glass using different crystallization processes. Stress modeling reveals much higher plastic strain in the stainless steel using SL16 glass-ceramic when the GCtSS seal cools from Tset. Upon heating tensile stresses start to develop at the GC-SS interface before the temperature reaches Tset. On the other hand, the much lower plastic deformation in stainless steel accumulated during cooling using NL16 glass-ceramic allows for radially compressive stress at the GC-SS interface to remain present when the seal is heated back to Tset. The qualitative stress comparison suggests that with a better match of thermal strain rate to that of stainless steel, the NL16 glass-ceramic not only improves the hermeticity of the GCtSS seals, but would also improve the reliability of the seals exposed to high-temperature and/or high-pressure abnormal environments.

Public concern regarding the effects of noise generated by the detonation of excess and obsolete explosive munitions at U.S. Army demolition ranges is a continuing issue for the Army's demilitarization and disposal groups. Recent concerns of citizens living near the McAlester Army Ammunition Plant (MCAAP) in Oklahoma have lead the U.S. Army Defense Ammunition Center (DAC) to conduct a demonstration and evaluation of noise abatement techniques that could be applied to the MCAAP demolition range. With the support of the DAC, MCAAP, and Sandia National Laboratories (SNL), three types of noise abatement techniques were applied: aqueous foams, overburden (using combinations of sand beds and dirt coverings), and rubber or steel blast mats. Eight test configurations were studied and twenty-four experiments were conducted on the MCAAP demolition range in July of 2000. Instrumentation and data acquisition systems were fielded for the collection of near-field blast pressures, far-field acoustic pressures, plant boundary seismic signals, and demolition range meteorological conditions. The resulting data has been analyzed and reported, and a ranking of each technique's effects has been provided to the DAC.

Abstract not provided.