Criteria

Display:

Results

Viewing 211 to 240 of 4791
2012-10-22
Journal Article
2012-01-2109
Laurence Wesson
Successful use of fiber optic interconnects in high-performance platforms and applications depends on viable technologies for their repair and installation. Splicing is often desirable, either to repair a damaged interconnect or to install it, particularly where it is difficult or impossible to access all necessary locations for complete removal and replacement. However, reliable aerospace cable splices must endure conditions as adverse as those for which the original cable was specified. In addition, the splicing technology must be usable with a high degree of reliability under difficult aerospace working conditions. Mechanical splices have shown some promise for the repair of multi-mode aerospace fiber cables, but they face daunting difficulties in splicing single mode fiber cables, which are being ever more seriously considered for new and upgraded systems.
2012-10-22
Journal Article
2012-01-2233
Michael Ballas, Fred Potter
Aircraft-level health management requires effective management of data flow. As future aircraft adopt conditioned base maintenance (CBM) and/or integrated vehicle health management (IVHM) protocols, there is need to manage infinitely more data communication on and off the aircraft. This paper explores the idea of employing an Electronic Power Distribution System (EPDS) as a “network backbone” for aircraft-level prognostics. Using EPDS to capture and distribute this data provides a practical solution that minimizes system hardware on future CBM/IVHM enabled aircraft. Employing the Electronic Circuit Breaker (ECB) in a more enhanced sensor state and as a data communication tool, provides tremendous value given its multipurpose capability.
2012-10-22
Journal Article
2012-01-2239
John E. James
Aviation battery maintenance is continuing to evolve. Much recent effort has been devoted to battery redesign to totally maintenance free or non-maintainable batteries. These batteries are placed into service and replaced at predetermined intervals. Still, some batteries are failing before their scheduled replacement period. For this reason attention is being focused on methods to transition batteries to an on-condition maintenance status. Nickel-Cadmium (NiCd) and Valve Regulated Lead-Acid (VRLA) are used to start engines, provide emergency back-up power, and assure ground power capability for maintenance and pre-flight checkout. Various Lithium-based battery chemistries are also now being developed and considered for use in these applications. As these functions are mission essential, State of Health (SoH) recognition is critical. SoH includes information regarding battery energy, power and residual cycle life.
2012-10-22
Journal Article
2012-01-2234
Freeman Rufus, Ash Thakker, Sean Field, Nathan Kumbar
Electrical and mechanical failures (such as bearing, winding and rotating-diode failures) combine to cause premature failures of the generators, which become a flight safety issue forcing the crew to land as soon as practical. Currently, diagnostic / prognostic technologies are not implemented for aircraft generators where repairs are time-consuming and costly. This paper presents the development of feature extraction and diagnostic algorithms to 1) differentiate between these failure modes and normal aircraft operational modes; and 2) determine the degree of damage of a generator. Electrical signature analysis (ESA) based time-domain features were developed to distinguish between healthy and degraded generators while taking into account their operating conditions. Frequency-domain based ESA techniques are used to identify the degraded components within the generators.
2012-09-24
Technical Paper
2012-01-2056
Rod Huisinga, Kurt Rottier, John Baertlein, Alex Kaye
The designers of heavy-duty off-road vehicles have been facing increasing pressure to reduce the cost and time required for assembly and maintenance. While the requirement to reduce assembly times is mainly an OEM driven objective, the requirement to reduce maintenance times is frequently driven by the customer. The design team is usually faced with the challenge of balancing functional requirements with what are often viewed as wish lists of easy assembly and maintenance, under the pressure of ever shorter development cycles. As a result, vehicle maintainability and ease of assembly are often overlooked early in the design cycle which can lead to less than desired results. This paper explores the design objectives and resultant solutions which were developed in the creation of the power-pack of a heavy-duty off-road vehicle.
2012-09-24
Technical Paper
2012-01-2032
Mahesh J Pardeshi, Ravindra Rajhans, M Srinivas, Shailesh Patil, Gautam Pingle
Designing a cabin tilting system for Light Commercial Vehicles using a single torsion bar becomes challenging considering the operator safety and stringent design weight targets. Performance of a good tilting system entirely depends on cabin mass and location of centre of gravity with respect to (w.r.t) to tilting pivot point. Cabin Mass and COG location are very difficult to estimate while designing a new cabin as it is dependent on the maturation of all other cabin aggregates and also the accessories added by the customer. Incorporation design parameter changes like increasing cab tilting angle and increasing torsion bar length, in the later stages of product development, becomes expensive. The objective of this paper is to come up with an optimum design of a single torsion bar tilting employing “Taguchi optimization” for deciding the optimum levels of control factors, which ensures desired performance (i.e tilting effort vs.
2012-04-16
Technical Paper
2012-01-1036
Richard A. Scholer, Michael Bourton, Dan Mepham, Arindam Maitra, Tim Godfrey, Doug Oliver, Donthy Venkatesh, Eloi Taha, Michael Muller, Cliff Fietzek
This paper is the third in the series of documents designed to record the progress on the SAE Plug-in Electric Vehicle (PEV) communication task force. The initial paper (2010-01-0837) introduced utility communications (J2836/1™ & J2847/1) and how the SAE task force interfaced with other organizations. The second paper (2011-01-0866) focused on the next steps of the utility requirements and added DC charging (J2836/2™ & J2847/2) along with initial effort for Reverse Power Flow (J2836/3™ & J2847/3). This paper continues with the following: 1. Completion of DC charging's 1st step publication of J2836/2™ & J2847/2. 2. Completion of 1st step of communication requirements as it relates to PowerLine Carrier (PLC) captured in J2931/1. This leads to testing of PLC products for Utility and DC charging messages using EPRI's test plan and schedule. 3. Progress for PEV communications interoperability in J2953/1.
2012-04-16
Journal Article
2012-01-0070
Jing Li, Zissimos Mourelatos, Amandeep Singh
Reliability is an important engineering requirement for consistently delivering acceptable product performance through time. It also affects the scheduling for preventive maintenance. Reliability usually degrades with time increasing therefore, the lifecycle cost due to more frequent failures which result in increased warranty costs, costly repairs and loss of market share. In a lifecycle cost based design, we must account for product quality and preventive maintenance using time-dependent reliability. Quality is a measure of our confidence that the product conforms to specifications as it leaves the factory. For a repairable system, preventive maintenance is scheduled to avoid failures, unnecessary production loss and safety violations. This article proposes a methodology to obtain the optimal scheduling for preventive maintenance using time-dependent reliability principles.
2012-04-16
Journal Article
2012-01-0064
Vijitashwa Pandey, Zissimos Mourelatos
In this article we present an approach to identify the system topology using simulation for reliability calculations. The system topology provides how all components in a system are functionally connected. Most reliability engineering literature assumes that either the system topology is known and therefore all failure modes can be deduced or if the system topology is not known we are only interested in identifying the dominant failure modes. The authors contend that we should try to extract as much information about the system topology from failure or success information of a system as possible. This will not only identify the dominant failure modes but will also provide an understanding of how the components are functionally connected, allowing for more complicated analyses, if needed. We use an evolutionary approach where system topologies are generated at random and then tested against failure or success data. The topologies evolve based on how consistent they are with test data.
2012-04-16
Technical Paper
2012-01-0125
Seyed Ehsan Samadani, Roydon A. Fraser, Michael Fowler
Due to the high power and energy density and also relative safety, lithium ion batteries are receiving increasing acceptability in industrial applications especially in transportation systems with electric traction such as electric vehicles and hybrid electric vehicles. In this regard, to ensure performance reliability, accurate modeling of calendar life of such batteries is a necessity. In fact, potential failure of Li-ion battery packs remains a barrier to commercialization. Battery pack life is a critical feature to warranty and maintenance planning for hybrid vehicles, and will require adaptive control systems to account for the loss in vehicle range, and loss in battery charge and discharge efficiency. Failure not only results in large replacement costs, but also potential safety concerns such as overheating or short circuiting which may lead to fires.
2012-04-16
Technical Paper
2012-01-1342
Dimitrios T. Hountalas, Antonis A. Antonopoulos, Georgios N. Zovanos, Roussos G. Papagiannakis
High efficiency, power concentration and reliability are the main requirements from Diesel Engines that are used in most technical applications. This becomes more important with the increase of engine size. For this reason the aforementioned characteristics are of significant priority for both marine and power generation applications. To guarantee efficient engine operation and maximum power output, both research and commercial communities are increasingly interested in methods used for supervision, fault-detection and fault diagnosis of large scale Diesel Engines. Most of these methods make use of the measured cylinder pressure to estimate various critical operating parameters such as, brake power, fuel consumption, compression status, etc. The results obtained from the application of any diagnostic technique, used to assess the current engine operating condition and identify the real cause of the malfunction or fault, depend strongly on the quality of these data.
2012-04-16
Journal Article
2012-01-0576
Shane Richardson, Geoff Hughes, Tandy Wei Pei Pok, Nikola Josevski, Tia Orton, Chris Jones
Within Australia there are seven States and two Territories, each with their own Government Authority which were until recently all using slightly different criteria to define the criteria between a Repairable Write-Off (RWO) and a Statutory Write-Off (SWO). Under the national framework for the management of Written-Off Vehicle's (WOV's) developed by the National Motor Vehicle Theft Reduction Council (NMVTRC) any collision, fire, water or weather-event damaged vehicle declared by an insurer to be a total loss must be classified to be either a SWO or RWO. Under the current Australian regime a SWO may only be sold subject to a statutory restriction that it may only be used for parts or scrap metal. A RWO may be repaired and re-registered subject to the vehicle passing specific safety and identification inspections. A set of State and Territory based technical criteria determine when a WOV should be classified an SWO.
2012-02-29
Technical Paper
2012-01-1503
Steven Maughan, Nathan Maughan
Temperature and energy losses in Ground Support Equipment (GSE) Pre-Conditioned Air (PCA) flexible ducting have a significant effect on the overall performance the PCA system. Providing the right size (diameter) and sufficiently insulated ducting is essential for the success of the system to adequately cool or heat an aircraft. Traditional HVAC temperature loss and energy loss estimating methods or rules of thumb are difficult to apply due to the specialized nature of the ducting and its application. Using fundamental heat transfer and general energy loss principles, custom tools were developed to model and predict these losses. Empirical testing has been used to verify the predictions. Having these tools enables the correct selection of duct size, length, and type for the particular needs of the PCA system.
2012-02-29
Technical Paper
2012-01-1507
Antonio Dumas, Michele Trancossi, Mauro Madonia, Maurizio Bonnici, Piergiorgio Scaccaglia, Mario Guareschi
This paper presents a novel concept of acclimatized container to increase people comfort in case of temporary housing. It is based on the ZEBRA concept (Zero Energy Building Renewable Addicted) concept studied by Università of Modena e Reggio Emilia. The original concept developed for industrial building has been extended to mobile metallic housing systems such as the containers transported by trucks which are used for troops and military command during field operations. This system does not require any external source of energy. It requires only the presence of a water well or drilling a hole to place inside a closed loop exchanger which is used to stabilize temperature of internal water which is used as a dynamic thermal barrier which maintains in the wellness conditions inside the mobile housing equipment. Energetic costs of this system are related only to the very reduced energy necessary for water pumping operations.
2012-02-29
Technical Paper
2012-01-1501
G. Patrick Brown
Examination of existing GSE site and building layouts and specific building elements lead to keys to improved GSE maintenance productivity that can be created with proper building design: Which site layouts provide proper staging and storage areas? Which building configurations help create the most efficient operations? What special building design features and equipment help to expedite vehicle throughput? Conclusions are drawn from design and construction experience, and from the examination of existing facilities, that provide guidelines for planning the new facility. How big should the facility be? How does air traffic growth influence GSE maintenance planning? What factors should be considered in planning a GSE maintenance facility? The paper also offers a brief checklist for the GSE Maintenance Facility planning process.
2011-10-18
Technical Paper
2011-01-2523
Enrique Soriano, Pedro Del Valle
The optimization of the available energy within a vehicle is one of the key drivers for all the ongoing projects. This topic is even more critical when the possibility of recharge energy into the vehicle it is quite improbable or even impossible. Hence all the system involved in the energy management shall create synergies. The Thermal Management is based on two paramount bases. The first one is the location of thermal sources (it can rather been cold sinks or heat sources). The second is the transportation of the energy from one source to a sink. The identification of the sources is based on the vehicle necessities. The definition of the transportation means depend on the vehicle capacities. Traditional system to transport the heat from one place to another are based on fluid displacement. Therefore they need some energy to pump this fluid. In the last years the use of passive transportation means is being developed in the aerospace industry.
2011-10-18
Technical Paper
2011-01-2664
Serdar Uckun, Tolga Kurtoglu, Peter Bunus, Irem Tumer, Christopher Hoyle, David Musliner
The complexity of modern aerospace vehicles is growing constantly. New technologies create opportunities for higher levels of integration. Modern vehicles contain a larger number of components that interact with each other in non-linear and often unpredictable ways. Unintended interactions lead to unexpected behaviors and consequences, some of which have proven to be catastrophic. A key technical challenge in developing such complex systems is to ensure that catastrophic subsystem and component interactions are well understood and contained prior to full-scale development. To address these challenges, the U.S. Defense Advanced Research Projects Agency (DARPA) is investing in novel methods for design and verification of complex systems. The META program is specifically aimed at compressing the timeline for product development and deployment of complex defense systems, through model-based design and manufacturing.
2011-10-18
Technical Paper
2011-01-2608
Hesham Azzam, Jim McFeat
An essential part of the SHM validation effort is to check the presence and adequacy of the methods required to validate the correct functionality of each SHM task, which can be targeted at detecting structural faults. The ultimate proof of the correct functionality is validation evidence, e.g. crack detection evidence, observed during the operation of the aircraft. However, the occurrences of structural faults such as cracks are infrequent, and hence, years of flight tests might be required to collect validation evidence; small numbers of flights would be only sufficient to prove the system's “fitness for flight” and would be insufficient to prove “fitness for purpose”. Validation evidence can be collected during laboratory tests by inducing faults in structural specimens and examining the SHM detection capability.
2011-10-18
Technical Paper
2011-01-2606
Wolfgang R. Habel, Nadine Kusche, Sven Munzenberger, Vivien G. Schukar
Strain sensors embedded in or attached to structural components have to measure the real deformation of the structure over the whole period of use. The user must know how reliably installed sensors provide strain measurement results. For this purpose, test facilities or coupon tests are used. In order to characterize the strain transfer quality from the host structure into surface-applied strain sensors, a unique testing facility has been developed. This facility can be used both for fiber optic and resistance strain sensors. Originally developed for fiber Bragg grating based sensors, the KALFOS facility (= \bc\ba\blibration of \bfiber \boptic \bsensors) uses Digital Image Correlation (DIC) and Electronic Speckle Pattern Interferometer (ESPI) as unbiased referencing methods. It is possible to determine experimentally the strain transfer mechanism under combined thermal and mechanical loading conditions.
2011-10-18
Technical Paper
2011-01-2804
Philippe Goupil, Andres Marcos
The state-of-practice for aircraft manufacturers to diagnose guidance & control faults and obtain full flight envelope protection at all times is to provide high levels of dissimilar hardware redundancy. This ensures sufficient available control action and allows performing coherency tests, cross and consistency checks, voting mechanisms and built-in test techniques of varying sophistication. This hardware-redundancy based fault detection and diagnosis (FDD) approach is nowadays the standard industrial practice and fits also into current aircraft certification processes while ensuring the highest level of safety standards. In the context of future “sustainable” aircraft (More Affordable, Smarter, Cleaner and Quieter), the Electrical Flight Control System (EFCS) design objectives, originating from structural loads design constraints, are becoming more and more stringent.
2011-10-18
Technical Paper
2011-01-2704
Ravi Rajamani, Nicholas Waters
The use of Engine Health Management (EHM) systems has been growing steadily in both the civilian and the military aerospace sectors. Barring a few notable exceptions (such as certain temperature and thrust margin monitoring) regulatory authorities around the world have not required these systems to be certified in any way. This is changing rapidly. New airframes and engines are increasingly being designed with the assumption that EHM will be an integral part of the way customers will operate these assets. This leads to a need for better guidelines on how such systems should be certified. The SAE E-32 committee on Propulsion System Health Monitoring is leading an industry-wide effort to develop a set of guidelines for certifying EHM systems.
2011-10-18
Technical Paper
2011-01-2703
Mahadevanna Basavaraj Shreshthi, Hanumantha Rao Desu V, Shaik Shafi Ahamed
Diagnosis of the ageing wiring systems in aircrafts, automobiles, industries, transportation, etc is essential. A wide variety of techniques are published in the literature claiming effective diagnosis of wire faults. The focus in this paper is limited to the techniques based on reflectometry principle. These are categorized in to Time Domain Reflectometry [TDR], Frequency Domain Reflectometry [FDR], Spread Spectrum Time Domain Reflectometry [SSTDR], Modified Spread Spectrum Time Domain Reflectometry [M-SSTDR], Noise Domain Reflectometry [NDR], Distributed Reflectometry[DR], Multi Carrier Reflectometry [MCR], Filterbank Multi Carrier Reflectometry [FBMCR] and Time Frequency Domain Reflectometry [TFDR]/Joint Time Frequency Domain Reflectometry [JTFDR] techniques. This paper presents a brief description of these techniques along with their comparison with respect to the key parameters and simulation results of Filter Bank Multi Carrier Reflectometry (FBMCR) technique.
2011-10-18
Journal Article
2011-01-2643
Luis Rabelo, Jorge Bardina, Yanshen Zhu, Jeppie Compton
This paper discusses the ground and range operations for a Shuttle derived Heavy-Lift Vehicle being launched from the Kennedy Space Center on the Eastern range. Comparisons will be made between the Shuttle and a heavy lift configuration (SLS-ETF MPCV - April 2011) by contrasting their subsystems. The analysis will also describe a simulation configuration with the potential to be utilized for heavy lift vehicle processing/range simulation modeling and the development of decision-making systems utilized by the range. In addition, a simple simulation model is used to provide the required critical thinking foundations for this preliminary analysis.
2011-10-18
Journal Article
2011-01-2665
Michael Roemer
One of the inherent functions of an integrated vehicle health management (IVHM) system is the reasoning capability that is built on the knowledge of how the individual line replaceable units (LRU) and subsystems are functionally interconnected across the vehicle. Once known and mathematically represented, the IVHM system has the ability to utilize knowledge obtained from the individual LRU/subsystems to determine the overall health state and functional capabilities of the vehicle. This process must go beyond the basic diagnoses of the observed health condition of the isolated subsystems and their remaining functionality. The IVHM reasoning process described herein employs a hierarchical structure that accounts for the failure modes at the LRU level and can also determine the functional impact of those LRUs in terms of remaining functional/operational availability at the subsystem and vehicle levels.
2011-10-18
Journal Article
2011-01-2674
Kenneth Pipe, Bernadette Culkin
Current alert setting methodologies based on setting defect detection alert thresholds for vibration and other Health & Usage Monitoring Systems (HUMS) indicators have many limitations, principally there is necessarily a compromise to be achieved between the true negative and false positive diagnostic metrics. This is true for all alert detection techniques from fixed thresholds through to Support Vector Machines. In this paper we describe techniques, validated using helicopter HUMS data, which do not invoke this compromise and independently minimise both the true negative and false positive rates. This paper will also demonstrate how the alert processing can be made more robust and overcome the problems introduced by HUMS data being both non-stationary, non-ergodic i.e. characteristics that change both with time and from platform to platform.
2011-10-18
Journal Article
2011-01-2702
Christian Modest, Kai Schories, Hauke Peer Lüdders, Frank Thielecke
In the paper at hand a model-based development approach for a diagnostic system for a multifunctional fuel cell system architecture will be presented. The approach consists primarily of four parts. The first part is a description of general steps needed to build an accurate component-based model of the system using a state of the art model-based diagnostic reasoning tool. As a first result there will be a static simulation model for nominal system behavior. The second part of the approach deals with the identification of safety critical failure conditions (SCFC) at a system level, e.g. low Power. The SCFCs are then mapped into the model. This means that categorized physical quantities and monitoring executives are chosen, that are appropriate for representing the specific SCFCs, e.g. low voltage at outlet of DC-DC converter module. According to step two there will be conflicts, meaning discrepancies between the simulated nominal and the mapped behavior.
2011-10-18
Journal Article
2011-01-2701
Hannes Wagner, Galin Nikolov, Andreas Bierig, Holger Spangenberg
Flight control systems of civil aircraft have undergone huge developments in the last decades. The current more/ all electric aircraft concepts lead to the replacement of the hydraulic actuators in the primary flight control systems by electromechanical systems. Integrating electromechanical systems in safety critical applications implies three main challenges: (a) the detection of all fault cases which could lead to a safety critical state, (b) finding measurement parameters capable to detect faults, and (c) the development of algorithms to detect faults under all flight conditions. Putting the scope on the health monitoring of the mechanical components of a direct drive actuator, a new technology based on piezoresistive thin film sensors (TFS) is presented and its potential shown by using defective ball bearings as an example.
2011-10-18
Journal Article
2011-01-2700
Ahmed Onsy, Brian A. Shaw, Jishan Zhang
Micro-pitting is a fatigue effect that occurs in geared transmission systems due to high contact stress, and monitoring its progression is vital to prevent the eventual failure of the tooth flank. Parameter signature analysis has been successfully used to monitor bending fatigue failure and advanced phases of gear surface fatigue failure such as macro-pitting and scuffing. However, due to modern improvements in steel production the main cause of gear contact fatigue failure can be attributed to surface micro-pitting rather than sub-surface phenomena. Responding to the consequent demand to detect and monitor the progression of micro-pitting, this study experimentally evaluated the development of micro-pitting in spur gears using vibration and oil debris analysis. The paper presents the development of an online health monitoring system for use with back-to-back gear test rigs.
2011-10-18
Journal Article
2011-01-2750
Athanasios Lois, Nikolaos Bertos, Athanasios Ziliaskopoylos
The process of checking inspection points on combat aircraft after a mission, is critical for their operational readiness. Manufacturers include specific inspection procedures in their maintenance handbooks. These procedures consist of detailed instructions for each check, the minimum time required to complete each check as well as a suggested sequence. However, it has been observed, that technical crews can complete inspection in less time than suggested by the manual, without violation of the time prescribed for each inspection point. In this work we will try to apply routing algorithms, to improve the total inspection time, by finding the optimal inspection sequence. This will be achieved without violating any constraint set by the manufacturer, except for the small reduction of the service time on some points. The algorithms we will use is the algorithmic set usually applied for the well-known PDPTW (pickup and delivery problem with time windows).
2011-10-18
Journal Article
2011-01-2714
Vincent Rouet, Bruno Foucher
TRIADE is a European Union project that focuses on the development of technological building blocks for Structure Health Monitoring (SHM) sensing devices in aeronautics. It is funded under the 7th framework program. In terms of objectives, the TRIADE project focuses on providing these technological building blocks and fully integrated prototypes in order to achieve power generation, power conservation, energy management and embedded powerful intelligence for data processing and storage for SHM sensing devices. The principal technological building blocks that the TRIADE project will provide are: - A low profile battery with high energy density which will be able to function in a harsh environment, - An energy harvester from vibration and electromagnetic RF, - Ultra low power sensors which will be designed in SOI technology, and - A neural network for data recording and damage assessment.
Viewing 211 to 240 of 4791