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Technical Paper

Smoke Particle Sizes in Low-Gravity and Implications for Spacecraft Smoke Detector Design

This paper presents results from a smoke detection experiment entitled Smoke Aerosol Measurement Experiment (SAME) which was conducted in the Microgravity Science Glovebox on the International Space Station (ISS) during Expedition 15. Five different materials representative of those found in spacecraft were pyrolyzed at temperatures below the ignition point with conditions controlled to provide repeatable sample surface temperatures and air flow conditions. The sample materials were Teflon®, Kapton®, cellulose, silicone rubber and dibutylphthalate. The transport time from the smoke source to the detector was simulated by holding the smoke in an aging chamber for times ranging from 10 to1800 seconds. Smoke particle samples were collected on Transmission Electron Microscope (TEM) grids for post-flight analysis.
Technical Paper

Detection of Smoke from Microgravity Fires

The history and current status of spacecraft smoke detection is discussed including a review of the state of understanding of the effect of gravity on the resultant smoke particle size. The results from a spacecraft experiment (Comparative Soot Diagnostics (CSD)) which measured microgravity smoke particle sizes are presented. Five different materials were tested producing smokes with different properties including solid aerosol smokes and liquid droplets aerosol smokes. The particulate size distribution for the solid particulate smokes increased substantially in microgravity and the results suggested a corresponding increase for the smokes consisting of a liquid aerosol. A planned follow on experiment that will resolve the issues raised by CSD is presented. Early results from this effort have provided the first measurements of the ambient aerosol environment on the ISS (International Space Station) and suggest that the ISS has very low ambient particle levels.
Journal Article

Measurement of Smoke Particle Size under Low-Gravity Conditions

Smoke detection experiments were conducted in the Microgravity Science Glovebox (MSG) on the International Space Station (ISS) during Expedition 15 in an experiment entitled Smoke Aerosol Measurement Experiment (SAME). The preliminary results from these experiments are presented. In order to simulate detection of a prefire overheated-material event, samples of five different materials were heated to temperatures below the ignition point. The smoke generation conditions were controlled to provide repeatable sample surface temperatures and air flow conditions. The smoke properties were measured using particulate aerosol diagnostics that measure different moments of the size distribution. These statistics were combined to determine the count mean diameter which can be used to describe the overall smoke distribution.
Technical Paper

An Investigation of Springback Stresses in Deep-Drawn Cups Using Diffraction Techniques

Prediction of springback has become a major focus in sheet metal forming. Validation of finite element codes that are being developed to predict springback require accurate property data and a more complete understanding of the residual stresses that are involved. To provide experimental data for these calculations, neutron and synchrotron X-ray diffraction measurements were carried out to determine the through-thickness distribution of axial and hoop (or tangential) residual stresses in deep-drawn steel and aluminum cups. The techniques are able to provide true spatial resolutions as low as 0.05 mm for a strain measurement on cups with ≤ 1 mm wall thickness. It was found that the stresses exhibit non-linear gradients through the thickness that also depend on the axial position.
Technical Paper

Evolution of Deformation-Induced Surface Morphologies Generated in Fe-Based Sheet

The complex strain states that exist within a real metal stamping are likely to generate different surface morphologies when compared to the same level of plastic strain produced via single pass deformation. This study quantifies the surface morphology that develops when an as-received traditional plain carbon steel sheet is deformed under two different single-pass, in-plane stretching operations. Roughness measurements performed in the as-received condition with a high resolution scanning laser confocal microscope revealed that an initial surface roughness did not appear to influence the deformation generated with biaxial strain. However, the initial surface roughness could have affected the deformation generated with uniaxial strain. The roughness data were fitted to a probability density function (PDF) and resulted in a near-ideal Gaussian distribution of the surface profile heights.
Technical Paper

Frameworks and Experimental Protocols for Information-Intensive Manufacturing

In a recent preliminary report of the National Research Council, it is stated that U.S. manufacturers are increasingly coming to depend upon information technology--computers, communications, and complex systems that combine the two. As a first approximation, any information infrastructure for manufacturing will be based on distributed systems of fast, reliable, and relatively inexpensive computers linked by high-speed, high-bandwidth networks.