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Journal Article

The Effects of Surface Texture on Fretting Fatigue between Fastener and Aluminum Structure

2010-09-28
2010-01-1854
Multi-fastener lap joints are vulnerable to fretting fatigue when they are subjected to repeated loading. In general the fretting fatigue condition leads to degraded properties of metallic structures due to the presence of the surface stress concentration resulting at the sites of fretting pits. In many cases, fretting can result in premature structure failures therefore a series of counter measures are frequently taken to minimize fretting especially at the fastener holes. One of major factors that affect the fretting phenomena between the fastener and fastener hole is the surface condition of the fasteners. In this study, the influences of the surface texture and the surface plating of the fastener on the joint life were investigated by conducting double lap shear fatigue testing. It has been found that the joint fretting fatigue resistance is very sensitive to the surface texture of the fastener and as the surface roughness of the fastener is reduced the joint life increases.
Journal Article

FC43®: A New Structural Panel Fastener

2012-09-10
2012-01-1888
Structural panel fasteners have been used in the aerospace industry for longer than the previous half century. This paper presents the new FC43® Panel Fastener with a novel retaining feature which enables the use of a full shank stud. The retaining feature can be used with a variety of thread configurations and is independent of nut style or head configuration, providing an unprecedented modularity for this type of fastening system. With a stud design that is free of slots or axial recesses, the FC43® provides higher mechanical performance than existing equivalent panel fasteners. Mechanical characteristics and performance comparisons with the most commonly used panel fasteners in the aerospace industry are also presented.
Technical Paper

International Space Station (ISS) Carbon Dioxide Removal Assembly (CDRA) Desiccant/Adsorbent Bed (DAB) Orbital Replacement Unit (ORU) Redesign

2007-07-09
2007-01-3181
The Carbon Dioxide Removal Assembly (CDRA) is a part of the International Space Station (ISS) Environmental Control and Life Support (ECLS) system. The CDRA provides carbon dioxide (CO2) removal from the ISS on-orbit modules. Currently, the CDRA is the secondary removal system on the ISS, with the primary system being the Russian Vozdukh. Within the CDRA are two Desiccant/Adsorbent Beds (DAB), which perform the carbon dioxide removal function. The DAB adsorbent containment approach required improvements with respect to adsorbent containment. These improvements were implemented through a redesign program and have been implemented on units on the ground and returning from orbit. This paper presents a DAB design modification implementation description, a hardware performance comparison between the unmodified and modified DAB configurations, and a description of the modified DAB hardware implementation into the on-orbit CDRA.
Technical Paper

Influence of Fastener Coatings on Fretting Fatigue

2007-09-17
2007-01-3890
Previous fatigue tests on mechanically fastened aerospace joints showed fatigue cracks often initiated in the countersink of the fastener hole where the fastener head was in contact with and caused fretting on, the hole bore. The work presented here evaluated the potential of a number of possible fastener coatings to reduce fretting and increase the fatigue life of the joint. The coatings were tested in a fretting fatigue test and in a ‘zero load’ fatigue test. The results showed that the best fretting resistance and fatigue life was obtained when aluminum pigmented coating (in accordance with NAS 4006) was used. The results also suggest that both test methods provide a similar ranking of performance. This means that the simpler fretting fatigue test may be useful as an initial screening method. However, more testing is needed to confirm this relationship.
Technical Paper

Development of an Automated Part Loading and Unloading System for a Cylindrical Die Thread Roller

2007-09-17
2007-01-3916
This paper outlines the design of a part transport and loading/unloading automation system for a cylindrical die thread roller, enumerating many of the design decisions encountered. Specifically, a transport tray system is proposed and prototyped as a benchmark for factory automation. Details of an automation system which will interface with the proposed transport tray system are discussed. A gripping system which accommodates a wide variety of fastener head styles is developed to work in conjunction with the tray concept, and prototyped with favorable results.
Technical Paper

Universal Splice Machine

2007-09-17
2007-01-3782
There is an increasing demand in the aerospace industry for automated machinery that is portable, flexible and light. This paper will focus on a joint project between BROETJE-Automation and Boeing called the Universal Splice Machine (USM). The USM is a portable, flexible and lightweight automated drilling and fastening machine for longitudinal splices. The USM is the first machine of its kind that has the ability not only to drill holes without the need to deburr, (burrless drilling) but also to insert fasteners. The Multi Function End Effector (MFEE) runs on a rail system that is mounted directly on the fuselage using a vacuum cup system. Clamp up is achieved through the use of an advanced electromagnet. A control cart follows along next to the fuselage and includes an Automated Fastener Feeding System. This paper will show how this new advancement has the capabilities to fill gaps in aircraft production that automation has never reached before.
Technical Paper

Integrated Air Interchange System Performance for Early Internatonal Space Station Assembly Missions

1998-07-13
981588
A multi-element fixed control volume integrated air interchange system performance computer model has been developed and upgraded for the evaluation/assessment of atmospheric characteristics inside the crew compartments of the mated Orbiter and International Space Station (ISS). In order to ensure a safe, comfortable, and habitable environment for all the astronauts during the Orbiter/ISS docked period, this model was utilized to conduct the analysis for supporting the early ISS assembly missions. Two ISS assembly missions #2A and #4A were selected and analyzed.
Technical Paper

International Space Station Temperature and Humidity Control Subassembly Hardware, Control and Performance Description

1998-07-13
981618
The temperature and humidity of the air within the habitable areas of the International Space Station are controlled by a set of hardware and software collectively referred to as the Temperature and Humidity Control (THC) subassembly. This subassembly 1) controls the temperature of the cabin air based on a crew selected temperature, 2) maintains humidity within defined limits, and 3) generates a ventilation air flow which circulates through the cabin. This paper provides descriptions of the components of the THC subassembly, their performance ranges, and the control approach of the hardware. In addition, the solutions of the design challenges of maintaining a maximum case radiated noise level of NC 45, controlling the cabin air temperature to within ±2°F of a setpoint temperature, and providing a means of controlling microbial growth on the heat exchanger surfaces are described.
Technical Paper

Virtual Laboratory (VLAB) Concept Applied in a Life Science Laboratory

1998-07-13
981792
As pieces of the International Space Station (ISS) enter their test phase, access to information and data from the test laboratories must be made immediately available to analysts, managers, and customers. The Virtual Laboratory (VLAB) concept provides remote access to laboratory test data and other information, indirectly as archived data or directly as real-time data off the test bed. We applied VLAB to a life support system hardware test (the Trace Contaminant Control System, TCCS) in the Life Support Technology Center (LSTC). In this paper we describe the VLAB concept in the context of the TCCS hardware test.
Technical Paper

Evaluation of Alternatives to Electrodeposited Cadmium for Threaded Fastener Applications (II)

2008-09-16
2008-01-2312
Cadmium electroplating is coming under increasing pressure due to both environmental and worker safety issues. Since 2005, Alcoa Fastening Systems (AFS) and Lockheed Martin have been conducting a collaborative research program to identify the most appropriate fastener coating materials for a Cadmium (Cd) plating replacement. Four candidate coatings were selected for the initial Phase I evaluation: electroless nickel (EN), electroless nickel composite (EN-PTFE), electrodeposited surface mineralization based zinc-nickel (Zn-Ni), and electroplated aluminum (Al). The Phase I testing results indicated that the Zn-Ni and Al coatings were the best of the four candidates for Cd replacement. However, it is hard to conduct direct comparisons with different coating thicknesses, surface treatments, and lubrication among various Cd alternatives. Thus, further evaluation with more careful control of these parameters would be necessary.
Technical Paper

Effects of Fastener Coating and Shear Strength on Joint Lap Shear Strength

2008-09-16
2008-01-2311
In aerospace fastener industry, all materials used or being considered for fastener applications must meet specified minimum shear strength values tested via single-shear test and double-shear test. However, shear testing results are not as precise as tension and compression testing due to the introduction of friction and bending forces in the testing process, resulting in the difficulty in obtaining accurate test data. Previous study showed the various effects of coating tribology on fastener single and double shear strength. Experimental results, statistical analysis and finite element analysis all confirmed that surface tribology could significantly affect the shear strength test results. Comparing to un-coated or bare fasteners, confirmed that fasteners from the same lot exhibited significantly lower shear strength values after coating. This effect is well known in the Aerospace fastener industry.
Technical Paper

Integrated Electrical System Testing and Modeling for Risk Mitigation

2008-11-11
2008-01-2897
International Space Station (ISS) Payload Engineering Integration (PEI) organization adopted the advanced computation and simulation technology to develop integrated electrical system models based on the test data of various sub-units. This system model was used end-to-end to mitigate system risk for the integrated Space Shuttle Pre-launch and Landing configurations. The Space Shuttle carries the Multi-Purpose Logistics Module (MPLM), a pressurize transportation carrier, and the Laboratory Freezer for ISS, a freezer rack for storage and transport of science experiments from/to the ISS, is carried inside the MPLM. An end-to-end electrical system model for Space Shuttle Pre-Launch and Landing configurations, including the MPLM and Freezer, provided vital information for integrated electrical testing and to assess Mission success. The Pre-Launch and Landing configurations have different power supplies and cables to provide the power for the MPLM and the Freezer.
Technical Paper

A Quick Change System for Portable Fastening Tooling Systems

2009-11-10
2009-01-3269
The installation of aerospace fasteners with pneumatic or cordless tools generally requires specialized systems which are dedicated to the fastener hex size and torque, often requiring laborious disassembly for a configuration change. This paper presents a quick change system that can be used together with a large variety of tooling configurations and provides instant socket exchange without requiring wrenching or disassembly. A comparison with traditional socket system is made, highlighting the characteristics and benefits of this new technology in terms of ergonomics, productivity and cost.
Technical Paper

Evaluation of Alternatives to Electrodeposited Cadmium for Threaded Fasteners Applications (III)

2009-11-10
2009-01-3228
Since 2005, Alcoa Fastening Systems (AFS) and Lockheed Martin have been partnering to identify a Cadmium (Cd) plating replacement for threaded fasteners. Previously reported Phase I, II and III studies resulted in alternative coatings that indicated promise as suitable plating materials. Phase IV and V studies continued the program by testing two different fasteners (NAS1580 and NAS4452) manufactured in AFS facilities. Testing included plating material characterization such as coating thickness, torque-tension relationships, locking and breakaway torque measurements, salt spray (fog) corrosion, stress corrosion, and push-in and interference properties. Additionally, mechanical properties of the plated fasteners were tested (tensile, double shear, durability, and fatigue). Candidates included two electroplated zinc-nickel coating systems (Zn-Ni and Zn-Ni2) and an electrodeposited aluminum coating (AI).
Technical Paper

Efficient Assembly Integration and Test (EAIT) Moves Theory to Practice at a System Level to Effect Lean Outcomes on the Shop Floor

2009-11-10
2009-01-3169
This paper will describe the Efficient Assembly Integration and Test (EAIT) system level project operated as a partnership among Boeing business units, universities, and suppliers. The focus is on the successful implementation and sharing of technology solutions to develop a model based, multi-product pulsed line factory of the future. The EAIT philosophy presented in this paper focuses on a collaborative environment that is tightly woven with the Lean Initiatives at Boeing's satellite development center. The prototype is comprised of a platform that includes a wireless instrumentation system, rapid bonding materials and virtual test of guidance hardware there are examples of collaborative development in collaboration with suppliers. Wireless tools and information systems are also being developed across the Boeing Company. Virtual reality development will include university partners in the US and India.
Technical Paper

Portable Fastener Delivery and Installation System

2003-09-08
2003-01-2953
The Portable Fastener Delivery System or PFDS, has been developed at the Boeing St. Louis facility to streamline the manual fastener installation process. The PFDS delivers various fasteners, on demand, through a delivery tube to an installation tool used by the operator to install the fasteners in an aircraft assembly. This paper describes the PFDS in its current configuration, along with the associated Huck® International (now Alcoa Fastening Systems) installation tooling, as it is being implemented on the F/A-18E/F Nosebarrel Skinning application. As a “portable” system, the PFDS cart can be rolled to any location on the shop floor it might be needed. The system uses a removable storage cassette to cache many sizes and types of fasteners in the moderate quantities that might be required for a particular assembly task. The operator begins the installation sequence by calling for the particular fastener grip length needed using a wireless control pendant.
Technical Paper

An Integrated Human Modeling Simulation Process for the International Space Station, Intra-Vehicular Activity

2001-09-11
2001-01-3035
Defining a process for integrating human modeling within the design and verification activities of the International Space Station (ISS) has proven to be as important as the simulations themselves. The process developed (1) ensured configuration management of the required digital mockups, (2) provided consistent methodology for simulating and analyzing human tasks and hardware layout, (3) facilitated an efficient method of communicating design requirements and relaying satisfaction of contract requirements, and (4) provided substantial cost savings by reducing the amount of late redesign and expensive mockup tests. Human simulation is frequently the last step in the design process. Consequently, the influence it has on product design is minimal and oftentimes being used as a post-design verification tool.
Technical Paper

ESM Analysis of COTS Laundry Systems for Space Missions

2002-07-15
2002-01-2518
Clothing supply has been examined for historical, current, and planned missions. For STS, crew clothing is stowed on the orbiter and returned to JSC for refurbishment. On Mir, clothing was supplied and then disposed of on Progress for incineration on re-entry. For ISS, the Russian laundry and 75% of the US laundry is placed on Progress for destructive re-entry. The rest of the US laundry is stowed in mesh bags and returned to earth in the Multi Purpose Logistics Module (MPLM) or in the STS middeck. For previous missions, clothing was supplied and thrown away. Supplying clothing without washing dirty clothing will be costly for long-duration missions. An on-board laundry system may reduce overall mission costs, as shown in previous, less accurate, metric studies. Some design and development of flight hardware laundry systems has been completed, such as the SBIR Phase I and Phase II study performed by UMPQUA Research Company for JSC in 1993.
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

Use of Electromagnetic and Vacuum Forces on Aircraft Assembly

2002-10-01
2002-01-2630
Decades ago our innovative grandfathers developed the first automated riveting machines based on hard automation using kinematics and tools attached to a C-frame. The C-frame serves multiple functions: First, it holds the upper and lower tools in fixed positions relative to each other; second, it translates upper active tooling forces to the lower tool; and third, it embraces the part placed between the upper and lower tool. C-frames and newly developed yoke, ring and gantry machines, used for low level (first, second) fuselage and wing assembly are growing in size to exorbitant proportions to satisfy requirements of larger and larger structures. High costs are dictated by massive kinematics and complex controls that provide stability, precision, and process speed. All this is mainly needed because we have to carry mechanical forces around the part, from upper to lower tool along the C-frame, gantry, yoke, bridge, etc.
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