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Technical Paper

Human Centered Manufacturing: a Necessity for Enhancing Productivity and Competitiveness

1999-04-20
1999-01-1605
This paper argues in favor of a human-centered (anthropocentric) approach to modern manufacturing. The bases for these arguments are: (a) worker deskilling and creativity issues, (b) economics, and (c) unresolved problems in automation, such as software reliance and costs. Detailed arguments are avoided owing to space limitations. Finally, some issues confronting human-centered manufacturing are raised.
Technical Paper

The Lean and Agile Manufacturing Model

1999-04-20
1999-01-1611
The Lean and Agile Manufacturing Simulation Model simulates the concepts of lean and agile manufacturing. A “live” working factory model is used to contrast the operating styles between a typical “mass production” plant and a “lean” production plant. Participants work as a team to plan, fabricate, manufacture, assemble, and ship two types of products using three common manufacturing processes - Traditional Mass Production (Push), Just-In-Time Manufacturing (Pull), and Cellular Manufacturing (Cell). Model functions include; warehousing, fabrication, WIP storage, assembly, inspection, accounting and shipping utilizing a miniature factory model, complete with tools, fixtures, materials and shop floor paperwork transactions. The model initially utilizes a traditional Material Requirements Planning (MRP) based scheduling approach to operate the factory.
Technical Paper

Is There a Need for Human Factors and Error Management in General and Corporate Aviation?

1999-04-20
1999-01-1595
This paper explores the need for human factors and error management within the context of the general and corporate aviation environments. It discusses strategies currently employed in other segments of the aviation industry and how they might be utilized in the corporate and general aviation arenas. It also relates research findings and program successes experienced within the airline industry and makes recommendations as to how a consortial effort by industry organizations might be utilized to employ these strategies in corporate and general aviation operations.
Technical Paper

Corporate Aviation on the Leading Edge: Systemic Implementation of Macro-human Factors in Aviation Maintenance

1999-04-20
1999-01-1596
While majority of the airlines are struggling to implement macro human factors principles in their maintenance activities, at least eleven corporate aviation departments (CADs) in the country are showing signs of success. The implementation philosophy of these CADs differs from others, and from the airlines in one fundamental aspect: it enforces a behavior change rather than an attitude change among the CAD employees. Consequently, they strive to achieve an employee behavior which is consistent within and across their flight operations, maintenance, and management functions. Ethnographic research was conducted at one of the eleven eligible sites to develop a theoretical model which is representative of the structure, the strategy, and the processes used by these aviation departments to implement macro human factors principles in aviation maintenance. This model was then tested at three other CADs that have a implemented similar approach.
Technical Paper

SJ30-2 High Performance Business Jet Development: A Prototype Based Approach

1999-04-20
1999-01-1593
The SJ30-2 is a high performance, entry level business jet with the design goal of offering performance superior to other aircraft in its class. Critical data were obtained and evaluated early in the development program through flight and structural testing of a prototype aircraft. Prototype testing helped to achieve aggressive design goals and minimized potential design changes for the globally located manufacturing team. This prototype based approach reduced the program schedule risk in the production and certification phase.
Technical Paper

Experimental Investigation of Ice Adhesion

1999-04-20
1999-01-1584
An experimental study was conducted to investigate ice-adhesion on clean and coated aluminum surfaces. A test apparatus using the parallel plate linear shear technique was designed along with a data acquisition system for conducting the tests and recording the experimental data. A low pulling rate was applied to specially prepared test specimens for measuring the strength of ice adhesion for a range of test conditions. The effects of surface roughness, surface contamination, and water impurity on ice adhesion were investigated. In addition, tests were conducted to evaluate the effectiveness of a low ice-adhesion coating applied to aluminum test specimens. The results obtained showed that the bond between ice and metal was considerably lower for tap water than for distilled water. For the clean and coated aluminum surfaces the strength of ice adhesion varied with specimen roughness. However, no clear trend was established between ice adhesion strength and surface roughness.
Technical Paper

Application of Shape Memory Alloys for Leading Edge Deicing

1999-04-20
1999-01-1585
Ice accumulation on aircraft wings during flight is a dangerous situation. To deal with this problem, current deicing systems either prevent ice accumulation by heating or break the ice layer once it is formed by dynamic motion of a leading edge device such as a boot. These systems may be deficient due to excessive energy requirements or ineffectiveness. In this project, the feasibility of using shape memory alloy (SMA) composite material for deicing purposes is investigated. SMA such as Nitinol wire has an unusual characteristic where it can be trained to generate a compressive strain upon application of an electric current through the wire. Several different versions of two inch radius semi-circular SMA composite specimen were manufactured and tested at Wichita State University. Ice was successfully shed in static icing tests while each of the subsequent versions reduced the power input requirement.
Technical Paper

Fracture Mechanics Based Approach for Quantifying Corrosion Damage

1999-04-20
1999-01-1589
The objective of this project is to quantify structural degradation due to corrosion through a fracture mechanics based approach. The metric parameters employed are Equivalent Initial Flaw Size and general material loss. Another objective is to correlate a measurable property to the amount of structural durability damage from corrosion, ideally through current NDE technology, with eddy-current as the primary choice. The approach is comprised by the following areas: corroding aluminum alloys, evaluation of the corrosion through techniques such as surface roughness and eddy current, cyclic testing, calculation of corrosion metric, and, correlation between corrosion metric and physically measurable properties.
Technical Paper

Analysis Tools for DaDTA on Riveted Lap Joints

1999-04-20
1999-01-1587
Two specific concerns that could affect safety limits for aging aircraft are the effects of corrosion damage and widespread fatigue damage (WFD) on structural integrity. A common joint in fuselage structure is the riveted lap joint, which overlaps two fuselage skin panels. This design creates complex loading conditions that require various analysis methods for accomplishing a durability and damage tolerance (DaDT) analysis. Under an Air Force research project, Boeing evaluated the capabilities of several advanced analysis tools for assessing the effects of corrosion and WFD on the structural integrity of riveted lap joints.
Technical Paper

Analysis of Widespread Fatigue Damage in Lap Joints

1999-04-20
1999-01-1586
This paper describes research to analyze widespread fatigue damage in lap joints. The particular objective is to determine when large numbers of small cracks could degrade the joint strength to an unacceptable level. A deterministic model is described to compute fatigue crack growth and residual strength of riveted panels that contain multiple cracks. Fatigue crack growth tests conducted to evaluate the predictive model are summarized, and indicate good agreement between experimental and numerical results. Monte Carlo simulations are then performed to determine the influence of statistical variability on various analysis parameters.
Technical Paper

An Automated System for Drill Bit Verification

1999-04-20
1999-01-1565
Aerospace manufactures purchase millions of drill bits each year for the manufacture of large aircraft structures. This paper describes an ongoing research project for the development of an automated system to detect poor quality drill bits before they are put to use.
Technical Paper

Heating Aircraft Reciprocating Engines

1999-04-20
1999-01-1568
Aircraft engines need preheating to be able to start without damage in cold weather. It is possible to do this efficiently by placing a small amount of heat in the proper places. An installed electric system is very convenient and easy to use. A good design will be light weight and energy efficient. Corrosion in engines that operate in cold weather can be reduced or eliminated by the right preheater design and the proper operation of the engine. Some designs of preheater systems aggravate other problems. A certain amount of caution is needed in selecting the system. The unit should be specifically matched to the aircraft and engine.
Technical Paper

Evaluation of Chip-Tool Interface Conditions using Transparent Tools

1999-04-20
1999-01-1563
In-situ high speed photographic observations through transparent ceramic cutting tools have been used to observe the dynamic contact interactions at the chip-tool interface while cutting commercially pure copper under a range of cutting speeds and rake angles. Under all conditions it is observed that the chip slides over the rake surface of the tool close to the cutting edge. Under low cutting speeds some chip material is transferred to the tool where the chip curls out of contact with the tool in the form of a fairly thick deposit. At higher cutting speeds a fine layer of chip material is transferred to the tool closer to the cutting edge and the thick deposits formed at lower speed are removed. The tendency for deposition is decreased as the rake angle is decreased. In all cases the dynamic nature of the cutting process and the slow evolution of the deposition are clearly evident.
Technical Paper

Hole Quality Study in High Speed Drilling of Composite and Aluminum Sheet Metal

1999-04-20
1999-01-1564
Drilling is one of the most widely applied manufacturing operations. Millions of holes are drilled today in manufacturing industries especially in aerospace industry where high quality holes are essential. Rejection and rework rate of the products because of the bad hole is quite high. In this research graphite/honeycomb composite material and aluminum sheet metal has been used. The results show that drill geometry, speed and feed rate have substantial effects on the hole quality and also there was gradual variation of the thrust and lateral forces with feed rates.
Technical Paper

Multistage Sheet Metal Forming with Intermediate Annealing: Comparison of Finite Element Simulations with Experiments

1999-04-20
1999-01-1560
This paper describes a methodology to simulate multistage sheet metal forming with intermediate heat treatments and its application to the three stage forming of an engine nacelle inlet lip. This capability has been validated by comparing results of finite element simulations for plastic strains at various points in the sheet with values obtained experimentally using the strain circle technique.
Technical Paper

Fatigue Analysis of an Aircraft Wing Spar

1999-04-20
1999-01-1561
During full body fatigue testing, an aircraft wing spar initiated a crack from a rivet hole and crack growth data was obtained unique to the test spectrum loading. Fatigue testing of the 7050-T73511 spar material was used to obtain crack growth rate data and variable amplitude fatigue crack growth tests were performed on specimens fabricated from the spar material. Calculated results were in excellent agreement with these experimental results. A layered analysis of the adhesively bonded spar showed that the stress intensity in the lower cap was approximately constant, independent of crack length. When the constant stress intensity is used in a variable amplitude fatigue crack growth analysis, there is good correlation between the predicted and observed crack growth rates.
Technical Paper

Mathematical Models of Fastened Structural Connections

1999-04-20
1999-01-1576
The development of efficient and reliable methods for the design and analysis of fastened structural connections is among the most important problems in aerospace applications because fastened structural connections are common sites of failure initiation. Numerical simulation of fastened structural connections is difficult because there are complicated interactions between the fasteners and the structural components being joined and one of the most important attributes of a fastened connection, the clearance, is a stochastic variable. This paper presents a mathematical model for frictionless shear connections and its implementation within the framework of the p-version of the finite element method.
Technical Paper

Activities of the Federal Aviation Administration’s Aviation Weather Research Program

1999-04-20
1999-01-1578
Weather is a major cause of aircraft accidents and incidents and the single largest contributor to air traffic system delays. Through improvements in the knowledge of current weather conditions and reliable forecasts, the Federal Aviation Administration (FAA) can improve aviation safety, increase system capacity, and enhance flight planning and fuel efficiency. The FAA has established an Aviation Weather Research (AWR) program to address specific requirements for weather support to aviation by providing the capability to generate more accurate and accessible weather observations, warnings, and forecasts and also by increasing the scientific understanding of atmospheric processes that spawn aviation weather hazards. The goal of AWR is to provide meteorological research that leads to the satisfaction of specific aviation weather requirements.
Technical Paper

Residual Strength of an Aluminum Panel with a Centric Hole and One Cracked Ligament

1999-04-20
1999-01-1574
The residual strength of an aluminum panel with a centric hole and one cracked ligament was investigated experimentally. Each of the 7075-T6 aluminum panels which were tested included a cracked ligament of varying length on one side of the centric hole and an uncracked ligament on the other side of the hole. The failure of such a panel subjected to uniform tensile loading normally occurs according to the lower of two modes: brittle fracture or a net section type of yielding. On the other hand, the question of whether one or both ligaments fail is not easily answered. Results show that one or two ligament failure depends upon test conditions such as crack length and loading method. For short crack lengths, the uncracked ligament will fail almost simultaneously with the failure of the cracked ligament.
Technical Paper

Strength of Stiffened Panels with Multiple Site Damage

1999-04-20
1999-01-1575
Multiple site damage (MSD) on aging aircraft accumulates from fatigue loading over a period of time. For ductile materials such as 2024-T3 aluminum, MSD may lower the strength below that which is predicted by conventional fracture mechanics. An analytical model referred to as the linkup (or plastic zone touch) model has previously been used to describe this phenomenon. However, the linkup model has been shown to produce inaccurate results for many configurations. This paper describes several modifications of the linkup model developed from empirical analyses. These modified linkup models have been shown to produce accurate results over a wide range of configurations for both unstiffened and stiffened flat 2024-T3 panels with MSD at open holes. These modified models are easy to use and give quick and accurate results over a large range of parameters.
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