Dynamics of window glass fracture in explosions

An exploratory study was conducted under the Architectural Surety Program to examine the possibility of modifying fracture of glass in the shock-wave environment associated with terrorist bombings. The intent was to explore strategies to reduce the number and severity of injuries resulting from those attacks. The study consisted of a series of three experiments at the Energetic Materials Research and Testing Center (EMRTC) of the New Mexico Institute of Mining and Technology at Socorro, NM, in which annealed and tempered glass sheets were exposed to blast waves at several different levels of overpressure and specific impulse. A preliminary assessment of the response of tempered glass to the blast environment suggested that inducing early failure would result in lowering fragment velocity as well as reducing the loading from the window to the structure. To test that possibility, two different and novel procedures (indentation flaws and spot annealing) were used to reduce the failure strength of the tempered glass while maintaining its ability to fracture into small cube-shaped fragments. Each experiment involved a comparison of the performance of four sheets of glass with different treatments

Downhole steam generation: material studies

One enhanced oil recovery technique for extracting heavy crude from deep reservoirs by steam at the bottom of an injection well. Development of a downhole steam generator that will produce steam and inject it into formations at depths greater than 2500 feet is one objective of a Department of Energy/Sandia National Laboratories development effort - Project DEEP STEAM. Extensive material studies have been performed in support of Project DEEP STEAM; current efforts are devoted primarily to the selection and evaluation of materials for use in downhole steam generators. This paper presents observations of the performance of candidate metals and refractory ceramics (combustor liners) during tests of two prototypic, high pressure, diesel/air combustion, direct contact, downhole steam generators. The first downhole test of such a generator provides data on the performance of various metals (304L, 310 and 316S stainless steels and plain carbon steel) exposed for several weeks to a warm, aerated saltwater environment. A number of corrosion mechanisms acted to cause severely degraded perforance of some of the metals. Several refractory liner designs were evaluated during ground level tests of a generator having a ceramic-lined combustion chamber. Of the two refractories employed, alumina and silicon carbide, the alumina liners exhibited more serious surface degradation and corrosion

Physiological and behavioral effects of dextroamphetamine on Beagle dogs

The purpose of the study was to measure the effects of a dose of 0.2 mg/kg dextroamphetamine on body temperature, heart rate, motor activity, and associated behavior changes in Beagle dogs. Reliability of a collar-mounted accelerometer as an objective measure of motor activity was also investigated by comparing motor activity with that observed using video recordings. A total of 12 research colony Beagle dogs (13-20-months-old) served as their own control in this placebo-controlled crossover design, receiving both placebo and 0.2 mg/kg dextroamphetamine as treatment. Baseline and posttreatment values for body temperature, heart rate, and motor activity were obtained using a rectal temperature, heart rate monitor, and a collar-mounted accelerometer, respectively. Behavior sequences were filmed and analyzed. Repeated measures model indicated that dogs receiving a dose of 0.2 mg/kg dextroamphetamine had a significantly (P = 0.044) reduced heart rate as compared with placebo. There was no effect of treatment on the dogs\u2019 body temperature, motor activity, or other behaviors such as \u201clip-licking,\u201d \u201cpanting,\u201d and \u201cyawning.\u201d There was a significant linear and positive relationship between the gross motor activity as measured by observational video and the accelerometer counts (P 15% reduction in heart rate. However, no data exist on the various effects of a low dose (0.2 mg/kg) of oral dextroamphetamine in dogs. The results of this study indicate that although as a group the medicated dogs showed a significantly lower heart rate than the placebo group, individual Beagle dogs showed variability in changes of heart rate. The use of the accelerometer in this study is a reliable tool for measuring motor activity in the dog

Using Designed Residual Stress Profiles to Produce Flaw-Tolerant Glass

A processing approach has been identified and reduced to practice in which a residual stress profile can be designed such that cracks in a brittle material are arrested or grow in a stable fashion. In the procedure, cracks in the body encounter an increase in the magnitude of residual compression as the crack propagates. If correctly designed, the process increases strength, significantly decreases strength variability and gives rise to multiple cracking. This approach is demonstrated for an ion-exchanged silicate glass using four-point and biaxial flexure strength testing. Optical microscopy was used to study the morphology and development of the multiple cracking that precedes the final failure