Refine Your Search

Search Results

Viewing 1 to 16 of 16
Technical Paper

Traceable Part Batching Performance Modeling: A Simulation Case Study

2004-09-21
2004-01-2822
This paper addresses a simulation modeling case study of a batching process. The batching process exists in a multi-server, multi-queue aircraft component manufacturing system where all parts and batches are serial numbered for traceability. Every lot of parts requires a unique set of serial numbers and the sequence of batches is required to follow the airplane master production schedule. The study goal was to identify and provide solutions to shorten arrival time differences among parts going to the same batch in a system of more than 100 shared processes. Queue lengths, resource utilization, bottlenecks, and various scenario comparisons were yielded from simulation modeling exercises.
Technical Paper

The Lithium Hydroxide Management Plan for Removing Carbon Dioxide from the Space Shuttle while Docked to the International Space Station

2003-07-07
2003-01-2491
The Lithium Hydroxide (LiOH) management plan to control carbon dioxide (CO2) for the Shuttle while docked to the International Space Station (ISS) reduces the mass and volume needed to be launched. For missions before Flight UF-1/STS-108, the Shuttle and ISS each removed their own CO2 during the docked time period. To control the CO2 level, the Shuttle used LiOH canisters and the ISS used the Vozdukh or the Carbon Dioxide Removal Assembly (CDRA) with the Vozdukh being the primary ISS device for CO2 removal. Analysis predicted that both the Shuttle and Station atmospheres could be controlled using the Station resources with only the Vozdukh and the CDRA. If the LiOH canisters were not needed for the CO2 control on the Shuttle during the docked periods, then the mass and volume from these LiOH canisters normally launched on the Shuttle could be replaced with other cargo.
Journal Article

Shielding Effectiveness of Sodium Alanate and Ammonia Borane for Galactic Cosmic Ray and Solar Energetic Particle Event Environments

2008-06-29
2008-01-2163
Estimates of the effectiveness of the high-hydrogen containing materials, sodium alanate and ammonia borane, are made by calculating dose and dose equivalent for the 1977 solar minimum and 1970 solar maximum galactic cosmic ray spectra and for the large solar particle event spectra from the space era event of August 1972 and comparing their shielding effectiveness with that of polyethylene.
Journal Article

Self-Configuring Hybrid Duct System and Attachment Technologies for Environmental Control Systems

2009-11-10
2009-01-3277
Environmental Control Systems (ECS) ducts on airplanes are primarily fabricated from aluminum or thermoset composites, depending on temperature and pressure requirements. It is imperative to fabricate lightweight, cost effective, durable, and repairable systems with minimal tooling. It is also important that the duct systems are easy to assemble even with alignment issues resulting from structural variations, tolerance accumulation, variation from thermal expansion of different materials, and inherent duct stiffness. These requirements create an opportunity and need for a technology that can address all of these issues, while increasing performance at the same time. This report provides a background on current ECS ducting systems.
Technical Paper

Machining-Induced Residual Stress and Distortion

2005-10-03
2005-01-3317
Distortion and buckling of aluminum aerospace components can be caused by machining-induced residual stress or by residual stress induced earlier in material processing. This stress is characterized through layer removal experiments and measurements of surface location. This stress is correlated to two machining process parameters, which can be changed, in order to control distortion and buckling of machined metallic components. Experiments are presented which compare distortion of thin machined parts to distortion of chemically milled parts in order to uncouple material bulk stress from machining-induced stress.
Technical Paper

Friction Stir Welding-A Revolutionary New Joining Method

1998-09-15
982149
Friction Stir Welding (FSW) can achieve high quality welds in aluminum alloys that are of interest to the aerospace industry (e.g. alloys 2014, 2219, 7050 and numerous aluminum-lithium alloys). The low distortion solid-phase welds exhibit metallurgical and mechanical properties, including fatigue, which are superior to conventional fusion welds achieved by arc processes. FSW, although a relatively new welding technique, has been systematically developed and proved by The Welding Institute (TWI) under contract to an international group of sponsors, one of which is The Boeing Company. To further validate the process, The Boeing Company conducted separate development activities including detailed mechanical testing of welds made from the FSW process.
Technical Paper

Experimental Study of Hole Quality in Drilling of Titanium Alloy (6AL-4V)

2002-04-16
2002-01-1517
This paper presents the experimental study of hole quality parameters in the drilling of titanium alloy (6Al-4V). Titanium alloy plates were drilled dry using three types of solid carbide drills i.e. 2-flute helical twist drill, straight flute and three-flute drill. The objective was to study the effects of process parameters like feed rate, speed and drill bit geometry on the hole quality features. Typical hole quality features in a drilling process are the hole quality measures such as surface roughness, hole diameter, hole roundness and burr height. The results indicate that proper selection of speed, feed rate, and drill geometry can optimize metal removal rate and hole quality.
Technical Paper

Electromagnetic Forming of Various Aircraft Components

2005-10-03
2005-01-3307
Electromagnetic forming (EMF) technology has been used lately for the joining and assembly of axisymmetric parts in the aerospace and automotive industries. A few case studies of compressive-type joining processes applied on both aluminum and titanium or stainless tubes for aerospace applications are presented. In the first case study, tests were conducted using 2024-T3 drawn tubes joined with a steel end fitting to form a torque tube using different forming variables including: the fitting geometry, material formability and forming power (KJ). The power setting and the fitting geometry were optimized to improve the fatigue life, torque off, and the axial load capability of the torque tube joints to drive the leading and trailing edge high-lift devices.
Journal Article

Development of Orbital Drilling for the Boeing 787

2008-09-16
2008-01-2317
The new materials and material combinations such as composites and titanium combinations used on today's new airplanes are proving to be very challenging when drilling holes during manufacturing and assembly operations. Orbital hole drilling technology has shown a great deal of promise for generating burr free, high quality holes in hard metals and in composite materials. This paper will show some of the orbital drilling development work Boeing is doing with Novator to overcome the obstacles of drilling holes in a combination of both hard metals and composites. The paper will include a new portable orbital drilling system designed for these challenging applications as well as some test results achieved with this system.
Technical Paper

Development of Non-Metallic Fastener Designs for Advanced Technology Structural Applications

2004-09-21
2004-01-2821
Fastening metallic structure for aerospace applications is relatively straightforward and has been done for some time. Dealing with advanced composites, though, requires a significantly different technological approach, especially primary structure. Although composite material utilization has increased enormously in civil and military aircraft in recent years, the application of composite materials to primary aircraft structure has not kept pace and is still greeted with some skepticism in the aerospace community. In particular, no major transport manufacturer has yet employed composite components for fuselage or wing primary structure. This appears to be changing rather rapidly with the introduction and the evolution of new airframes such as the 7E7 and Blended Wing Body (BWB) concepts.
Technical Paper

Development and Implementation of Sol-Gel Coatings for Aerospace Applications

2009-11-10
2009-01-3208
A family of water-based sol-gel coatings has been developed as an environmentally-friendly alternative to traditional aerospace finishing materials and processes. The sol-gel hybrid network is based on a reactive mixture of an organo-functionalized silane with a stabilized zirconium complex. Thin films of the material self-assemble on metal surfaces, resulting in a gradient coating that provides durable adhesion for paints, adhesives, and sealants. Use of the novel coating as a surface pretreatment for the exterior of commercial aircraft has enabled environmental, health, and safety benefits due to elimination of hexavalent chromium, and flight test and early fleet survey data support the laboratory observations that the sol gel coating reduces the occurrence of “rivet rash” adhesion failures. Modifications of the basic inorganic/organic hybrid network have yielded multifunctional coatings with promise for applications such as corrosion control and oxidation protection.
Technical Paper

Assessment of Lithium Hydroxide Conservation Via International Space Station Control of Orbiter Carbon Dioxide

2002-07-15
2002-01-2271
In order to conserve mass and volume, it was proposed that the International Space Station (ISS) control the level of carbon dioxide (CO2) in the Space Shuttle Orbiter while the Orbiter is docked to the ISS. If successful, this would greatly reduce the number of lithium hydroxide (LiOH) canisters required for each ISS-related Orbiter mission. Because of the impact on the Orbiter Environmental Control and Life Support Subsystem (ECLSS), as well as on the Orbiter flight manifest, a Space Shuttle Program (SSP) analysis was necessary. STS-108 (ISS UF1) pre-flight analysis using the Personal Computer Thermal Analyzer Program (PCTAP) predicted that the ISS would be able to control the level of CO2 in the Orbiter (and throughout the stack) under nominal conditions with no supplemental LiOH required. This analysis assumed that the Carbon Dioxide Removal Assembly (CDRA) located in the U.S.
Technical Paper

Analysis to Characterize Fresh vs. Aged Shuttle Orbiter Lithium Hydroxide Performance

2006-07-17
2006-01-2048
A recent endeavor has been undertaken to understand the performance of Shuttle Orbiter lithium hydroxide (LiOH) canisters used during STS-114. During this mission, the crew relied on both fresh LiOH and aged LiOH stored on the International Space Station (ISS). Due to the Space Shuttle being grounded after the Columbia accident, the canisters stored on ISS had passed the certified two-year shelf life and were considered expired. The focus of the analysis was to determine the performance of expired LiOH in relation to fresh LiOH and the accuracy of previous predictions1 regarding the performance of expired LiOH. Understanding the performance of expired LiOH is crucial in enabling the extension of the useful life of LiOH canisters. Extending the shelf life has ramifications not only in the current Shuttle program, but in regard to future exploration missions fulfilling the Vision for Space Exploration as well.
Technical Paper

Analysis of the Effect of Age on Shuttle Orbiter Lithium Hydroxide Canister Performance

2005-07-11
2005-01-2768
Recent efforts have been pursued to establish the usefulness of Space Shuttle Orbiter lithium hydroxide (LiOH) canisters beyond their certified two-year shelf life, at which time they are currently considered “expired.” A stockpile of Orbiter LiOH canisters are stowed on the International Space Station (ISS) as a backup system for maintaining ISS carbon dioxide Canisters with older (CO2) control. Canister with older pack dates must routinely be replaced with newly packed canisters off-loaded from the Orbiter Middeck. Since conservation of upmass is critical for every mission, the minimization of canister swap-out rate is paramount. LiOH samples from canisters with expired dates that had been returned from the ISS were tested for CO2 removal performance at the NASA Johnson Space Center (JSC) Crew and Thermal Systems Division (CTSD). Through this test series and subsequent analysis, performance degradation was established.
Journal Article

A Fresh Look at Radiation Exposures from Major Solar Proton Events

2008-06-29
2008-01-2164
Solar proton events (SPEs) represent the single-most significant source of acute radiation exposure during space missions. Historically, an exponential in rigidity (particle momentum) fit has been used to express the SPE energy spectrum using GOES data up to 100 MeV. More recently, researchers have found that a Weibull fit better represents the energy spectrum up to 1000 MeV (1 GeV). In addition, the availability of SPE data extending up to several GeV has been incorporated in analyses to obtain a more complete and accurate energy spectrum representation. In this paper we discuss the major SPEs that have occurred over the past five solar cycles (~50+ years) in detail - in particular, Aug 1972 and Sept & Oct 1989 SPEs. Using a high-energy particle transport/dose code, radiation exposure estimates are presented for various thicknesses of aluminum. The effects on humans and spacecraft systems are also discussed in detail.
X