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ISBN:
Category :
Languages : en
Pages : 16
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Book Description
Over the past two decades, Sandia has developed a variety of specialized analytical techniques for evaluating the long-term aging and stability of cable insulation and other related materials. These techniques have been applied to cable reliability studies involving numerous insulation types and environmental factors. This work has allowed the monitoring of the occurrence and progression of cable material deterioration in application environments, and has provided insights into material degradation mechanisms. It has also allowed development of more reliable lifetime prediction methodologies. As a part of the FAA program for intrusive inspection of aircraft wiring, they are beginning to apply a battery of techniques to assessing the condition of cable specimens removed from retired aircraft. It is anticipated that in a future part of this program, they may employ these techniques in conjunction with accelerated aging methodologies and models that the authros have developed and employed in the past to predict cable lifetimes. The types of materials to be assessed include 5 different wire types: polyimide, PVC/Glass/Nylon, extruded XL-polyalkene/PVDF, Poly-X, and XL-ETFE. This presentation provides a brief overview of the main techniques that will be employed in assessing the state of health of aircraft wire insulation. The discussion will be illustrated with data from their prior cable aging studies, highlighting the methods used and their important conclusions. A few of the techniques that they employ are widely used in aging studies on polymers, but others are unique to Sandia. All of their techniques are non-proprietary, and maybe of interest for use by others in terms of application to aircraft wiring analysis. At the end of this report is a list showing some leading references to papers that have been published in the open literature which provide more detailed information on the analytical techniques for elastomer aging studies. The first step in the investigation of aircraft wiring is to evaluate the applicability of their various techniques to aircraft cables, after which they expect to identify a limited subset of techniques which are appropriate for each of the major aircraft wiring types. The techniques of initial interest in the studies of aging aircraft wire are as follows: optical microscopy; mandrel bend test; tensile test/elongation at break; density measurements; modulus profiling/(spatially-resolved micro-hardness); oxygen induction time/oxygen induction temperature (by differential scanning calorimetry); solvent-swelling/gel fraction; infrared spectroscopy (with chemical derivatization as warranted); chemiluminescence; thermo-oxidative wear-out assessment; The first two techniques are the simplest and quickest to apply; those further down the list tend to be more information rich and in some cases more sensitive, but also generally more specialized and more time consuming to run. Accordingly, the procedure will be to apply the simplest tests for purposes of preliminary screening of large numbers of samples. For any given material type, it can be expected that only a limited number of the other techniques will prove to be useful, and therefore, the more specialized techniques will be used on a limited number of selected samples. Samples of aircraft wiring have begun to be released to the authors in late April; they include in this report some limited and preliminary data on these materials.
Author:
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ISBN:
Category : Electric wire, Insulated
Languages : en
Pages :
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The objective of this research study was to validate the Indenter Polymer Aging Monitor (Indenter), originally develop by The Electric Power Research Institute in the 1980s for use in utility nuclear power plants, as a means of characterizing aircraft wire degradation by means of monitoring the properties of the wire insulation. The Indenter is a portable, simple-to-operate, nondestructive instrument for gathering data, which could be used as a test method that monitors the aging of wires and cables by measuring the changes in compressive modulus. The data and analysis in this report demonstrates that insulation hardness measurements obtained with the Indenter can be correlated with accepted destructive methods such as elongation-at-break and Wire Insulation Deterioration Analysis System to provide a relative measure of wire insulation degradation.
Author: E. L. Brancato
Publisher:
ISBN:
Category :
Languages : en
Pages : 43
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Book Description
Life versus temperature curves of wire and cable insulations are needed to provide aircraft design engineers with information to design electrical circuits utilizing the minimum wire sizes required to maintain maximum reliability and yet reduce weight and bulk to a minimum. To establish the feasibility of obtaining such curves a procedure, employing functional evaluation and principles of statistical analysis, was developed and applied to produce curves of five wires representing the variations in insulation layer constructions specified in MIL-W-5086A. Cycling temperature studies were conducted on three of these wires, verifying the application of a relative aging factor formula which can be used to convert cyclic aging to the equivalent aging of a single temperature exposure. (Author).
Author:
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ISBN:
Category : Airplanes, Military
Languages : en
Pages : 36
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Author: E. L. Brancato
Publisher:
ISBN:
Category :
Languages : en
Pages : 18
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Book Description
A functional evaluation program was established which will provide a comparison of thermal service life of wire and cable insulation by combining the effects of heat aging with the most predominant service stresses. The stresses are necessarily of greater severity than normal service and thus provide relative life data rather than absolute values of service life. Experimental data of life versus aging temperature when statistically treated and the log of life versus the reciprocal of the absolute temperature plotted on semi-log paper approximates a straight line which can be represented by the Chemical Rate Equation. Temperature cycling studies conducted on a representative magnet wire insulation system indicate that reasonable estimates of service life under varying temperature conditions can be obtained by applying the relative aging factor principle. From the life versus temperature curve a relative aging factor can be derived which can be applied to convert aging time at any given temperature to a relative amount of normal life consumed at a reference temperature. When the high temperature exposures occur in known service cycles, it is possible to calculate the number of cycles of safe operation which can be expected of the cable. (Author).
Author: William M. Denny
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 0
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Book Description
"The Indenter is a nondestructive test method that monitors the aging of wires by measuring changes in compressive modulus, a mechanical property of insulation and jacket materials. When wires age, significant changes occur in a mechanical property before any changes occur in an electrical property. That is, the mechanical properties must change to the point of embrittlement and cracking before significant electrical changes are observed. Changes in mechanical properties typically have been evaluated by Elongation-at-Break (EAB) testing. However, EAB testing is destructive and requires relatively large specimens, making it undesirable for analyzing installed cables. As an alternative to EAB tests, Indenter tests that measure compressive modulus provide a systematic indication of material aging. Thus, Indenter data obtained during a research project that also obtained EAB (or other) data at the same level of aging can be correlated to predict remaining cable life. The goal of this research project was to develop the Indenter further so that it would be a nonintrusive, easy-to-use, nondestructive portable test device to help assess the aging condition of wires in aircraft. Significant enhancements to the design of the Indenter (both in hardware and software) during this project have advanced the state of the art of this technology and resulted in a more accurate, reliable, and easier-to-use instrument."--Page ii
Author: Joseph Kurek
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 98
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"The purpose of this initial research program was to evaluate the aging characteristics of three types of aircraft electrical wire : polyimide, poly trafluoroethylene/polyimide composite, and polyvinyl chloride/nylon. In addition, predictive models for the aging of these wire types were developed. These wire types were chosen because of their widespread use in commercial aircraft and the amount of reported incidents concerning them. The factors that cause the wire insulation to degrade were examined and techniques to determine when a wire will no longer be capable of transfer of electrical current were evaluated. The results in this study provided a platform to evaluate existing and new test methods that could be used to monitor the aging of wire in aircraft."--Report documentation page.
Author: Joseph Kurek
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 0
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Book Description
"The purpose of this initial research program was to evaluate the aging characteristics of three types of aircraft electrical wire : polyimide, poly trafluoroethylene/polyimide composite, and polyvinyl chloride/nylon. In addition, predictive models for the aging of these wire types were developed. These wire types were chosen because of their widespread use in commercial aircraft and the amount of reported incidents concerning them. The factors that cause the wire insulation to degrade were examined and techniques to determine when a wire will no longer be capable of transfer of electrical current were evaluated. The results in this study provided a platform to evaluate existing and new test methods that could be used to monitor the aging of wire in aircraft."--Report documentation page.
Author:
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ISBN:
Category : Aeronautics
Languages : en
Pages : 1000
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Author: Tillie K. Fowler
Publisher: DIANE Publishing
ISBN: 0756722519
Category :
Languages : en
Pages : 97
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Book Description
Witnesses: Elizabeth Erickson, Dir., Aircraft Certification Service, Fed. Aviation Admin. (FAA); Richard Healing, Chmn., Aircraft Wiring and Inert Gas Generator Working Group (AWIGG), and Dir., Navy Safety and Survivability, Office of the Assistant Secretary of the Navy; Kent V. Hollinger, Chair, Aging Transport Systems Rulemaking Advisory Committee (ATSRAC); Vince Press, Dir. of Marketing, Lectromec Design Co.; Dr. Bill Linzey, Lead Technician, Lectromec Design Co.; Alexis M. Stefani, Assistant Inspector General for Auditing, U.S. Dept. of Transportation; and Rep. James L. Oberstar and James A. Traficant.
