Engineering topics

Smith, James E., Jr.

Publications and source records attributed to Smith, James E., Jr..

8 records

NASA NTRS1992

High temperature aircraft research furnace facilities

Focus is on the design, fabrication, and development of the High Temperature Aircraft Research Furnace Facilities (HTARFF). The HTARFF was developed to process electrically conductive materials with high melting points in a low gravity environment. The basic principle of operation is to accurately translate a high temperature arc-plasma gas front as it orbits around a cylindrical sample, thereby making it possible to precisely traverse the entire surface of a sample. The furnace utilizes the gas-tungsten-arc-welding (GTAW) process, also commonly referred to as Tungsten-Inert-Gas (TIG). The HTARFF was developed to further research efforts in the areas of directional solidification, float-zone processing, welding in a low-gravity environment, and segregation effects in metals. The furnace is intended for use aboard the NASA-JSC Reduced Gravity Program KC-135A Aircraft.

Smith, James E., Jr.↗

NASA NTRS1992

Vacuum chamber translation/positioning mechanism and welding power supply controller

Welding in the vacuum of space represents an important and fundamental problem for space exploration. Repairs or connection of metal components on orbit or during travel to the moon or distant planets may be required. Cracks or holes in spacecraft skin or supporting structures external to the pressurized section will require some type of repair that must be permanently made to the skin or support by welding. The development of a translation/positioning system that will permit research into welding of metal samples in a small vacuum chamber located at Marshall Space Flight Center (MSFC) is addressed. The system and associated software was tested to the extent possible without the availability of the welder power supply or control computer that must be supplied by MSFC. Software has been developed for straight line welding. More extensive and varied translations are possible with simple alterations to the operating software to use the full capabilities of this three axes system. The source code 'VW.BAS' has been provided to serve as an example for further development of the vacuum welder translation system.

Smith, James E., Jr.↗

NASA NTRS1992

High temperature furnace modeling and performance verifications

Analytical, numerical, and experimental studies were performed on two classes of high temperature materials processing sources for their potential use as directional solidification furnaces. The research concentrated on a commercially available high temperature furnace using a zirconia ceramic tube as the heating element and an Arc Furnace based on a tube welder. The first objective was to assemble the zirconia furnace and construct parts needed to successfully perform experiments. The 2nd objective was to evaluate the zirconia furnace performance as a directional solidification furnace element. The 3rd objective was to establish a data base on materials used in the furnace construction, with particular emphasis on emissivities, transmissivities, and absorptivities as functions of wavelength and temperature. A 1-D and 2-D spectral radiation heat transfer model was developed for comparison with standard modeling techniques, and were used to predict wall and crucible temperatures. The 4th objective addressed the development of a SINDA model for the Arc Furnace and was used to design sample holders and to estimate cooling media temperatures for the steady state operation of the furnace. And, the 5th objective addressed the initial performance evaluation of the Arc Furnace and associated equipment for directional solidification. Results of these objectives are presented.

Smith, James E., Jr.↗

NASA NTRS1991

High temperature furnace modeling and performance verifications

A two dimensional conduction/radiation problem for an alumina crucible in a zirconia heater/muffle tube enclosing a liquid iron sample was solved numerically. Variations in the crucible wall thickness were numerically examined. The results showed that the temperature profiles within the liquid iron sample were significantly affected by the crucible wall thicknesses. New zirconia heating elements are under development that will permit continued experimental investigations of the zirconia furnace. These elements have been designed to work with the existing furnace and have been shown to have longer lifetimes than commercially available zirconia heating elements. The first element has been constructed and tested successfully.

Smith, James E., Jr.↗

NASA NTRS1988

Development of an endoscopic probe for radial metrology

The goal of this work was to design and build a prototype for conducting stress analysis and making spectroscopic measurements inside cavities. The objectives were as follows: (1) to develop a prototype for radial profilometry; (2) to explore the possibility of using the radial profilometer for spectroscopic analysis; and (3) to interface the prototype with various combinations of data acquisition and image processing equipment.

Gilbert, John A.↗

NASA NTRS1988

High temperature furnace modeling and performance verifications

Analytical, numerical and experimental studies were performed on two classes of high temperature materials processing furnaces. The research concentrates on a commercially available high temperature furnace using zirconia as the heating element and an arc furnace based on a ST International tube welder. The zirconia furnace was delivered and work is progressing on schedule. The work on the arc furnace was initially stalled due to the unavailability of the NASA prototype, which is actively being tested aboard the KC-135 experimental aircraft. A proposal was written and funded to purchase an additional arc welder to alleviate this problem. The ST International weld head and power supply were received and testing will begin in early November. The first 6 months of the grant are covered.

Smith, James E., Jr.↗

NASA NTRS1987

Cast iron freezing mechanisms

This task focused on liquid phase sintering and infiltration studies of refractory metals and metal composites. Particular emphases was placed on those powered metal compacts which produce liquid alloys in sintering. For this class of materials, heating to a two phase region causes the constituent components to react, forming an alloy liquid which must wet the solid phase. Densification is initially driven by the free energy effects which cause rapid rearrangement. Further densification occurs by evaporation and condensation, surface diffusion, bulk flow, and volume diffusion.

Lillybeck, N. P.↗

NASA NTRS1987

Transparent Analogs for Alloy Phase Studies

Report describes experiments to add information to data base supporting use of transparent, partially miscible liquids and solids as analogs in studies of alloy solidification. Behavior of these materials observed directly while they undergo liquid/liquid and liquid/solid phase transformations. Light-scattering techniques used to determine phase boundaries. Transparent analogs allow observation of both solidification patterns and processes leading to those patterns, whereas metal alloys require tedious post-solidification metallographic analyses because processes not generally observed. Experiments with transparent substances safer and cheaper since conducted at much lower temperatures.

Frazier, D. O.↗