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No Fault Found: The Search for the Root Cause

Chris Hockley
Cranfield Univ.-Samir Khan
  • Book
  • R-441
Published 2015-09-03 by SAE International in United States

Today, we are all strongly dependent on the correct functioning of technical systems. They fail, and we become vulnerable. Disruptions due to degradation or anomalous behavior can negatively impact safety, operations, and brand name, reducing the profitability of all elements of the value chain.

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Improvement of an Altitude Test Facility Capability in Glaciated Icing Conditions at DGA Aero-engine Testing

SAE International Journal of Aerospace

Cranfield Univ.-Hugo Pervier
CIRA Scpa-Biagio Esposito
  • Journal Article
  • 2015-01-2154
Published 2015-06-15 by SAE International in United States
The A06 test facility designed for combustor testing in altitude has been modified to be converted in an icing facility for probe testing. The objective was to be able to simulate ice crystals conditions at high altitude, high Mach number and low temperature. This facility has been upgraded in several steps extending the median size of the ice crystals produced and the ice water content range. The aero-thermal and icing capabilities have been assessed during commissioning tests. Finally, in order to prepare the calibration of the facility, some measurement techniques for cloud characterization have been selected or developed, especially for cloud uniformity measurement.
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New Slip Control System Considering Actuator Dynamics

SAE International Journal of Passenger Cars - Mechanical Systems

Cranfield Univ.-Amir Soltani
Univ. of California-Francis Assadian
  • Journal Article
  • 2015-01-0656
Published 2015-04-14 by SAE International in United States
A new control strategy for wheel slip control, considering the complete dynamics of the electro-hydraulic brake (EHB) system, is developed and experimentally validated in Cranfield University's HiL system. The control system is based on closed loop shaping Youla-parameterization method. The plant model is linearized about the nominal operating point, a Youla parameter is defined for all stabilizing feedback controller and control performance is achieved by employing closed loop shaping technique. The stability and performance of the controller are investigated in frequency and time domain, and verified by experiments using real EHB smart actuator fitted into the HiL system with driver in the loop.
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Modelling of Accelerating Non-Isothermal Liquid Jet Breakup Mechanisms

Cranfield Univ.-Ilai Sher
Cranfield Univ. / University of Port Harcourt-Ogheneruona E. Diemuodeke
Published 2014-10-13 by SAE International in United States
Fuel injector performance has a direct effect on the combustion efficiency, pollutant emissions and combustion instability of internal combustion engines. Liquid fuels are normally accelerated into an elevated combustion-chamber temperature to maintain a desirable homogeneous combustible mixture - liquid vapour and air. The accelerated jet breakup may be induced by cavitation, turbulent, hydrodynamic and aerodynamic forces interactions and variation in fluid properties. The absolute majority of studies have been devoted to the extensive study on some of the effects that cause jet instability and breakup, while others are still at their infant study. In particular, relatively few researchers have studied the combined effects of jet acceleration and non-isothermal condition on jet instability and breakup, despite its practical relevance in liquid fuel spray and combustion. A new analytical hydrodynamic instability and breakup model, which captured both jet acceleration and non-isothermal condition, for liquid jet is presented. The analytical model investigates the impact of two important phenomena on liquid jet instability and breakup; jet acceleration and non-isothermal conditions. These effects are naturally difficult to address by both…
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UAS Behaviour and Consistency Monitoring System for Countering Cyber Security Threats

Cranfield Univ.-Rodrigo Felix, John Economou, Kevin Knowles
Published 2014-09-16 by SAE International in United States
Upon their arrival, Unmanned Autonomous Systems (UAS) brought with them many benefits for those involved in a military campaign. They can use such systems to reconnoiter dangerous areas, provide 24-hr aerial security surveillance for force protection purposes or even attack enemy targets all the while avoiding friendly human losses in the process. Unfortunately, these platforms also carry the inherent risk of being built on innately vulnerable cybernetic systems. From software which can be tampered with to either steal data, damage or even outright steal the aircraft, to the data networks used for communications which can be jammed or even eavesdropped on to gain access to sensible information. All this has the potential to turn the benefits of UAS into liabilities and although the last decade has seen great advances in the development of protection and countermeasures against the described threats and beyond the risk still endures.With this in mind the present work will describe a monitoring system whose purpose is to monitor UAS mission profile implementation at both high level mission execution and at lower…
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The Aerodynamics of a Small Car Overtaking a Truck

SAE International Journal of Passenger Cars - Mechanical Systems

Cranfield Univ.-Kevin Garry, Jenny Holt
Tata Motors European Technical Centre-Jeff Howell
  • Journal Article
  • 2014-01-0604
Published 2014-04-01 by SAE International in United States
The influence of a large truck on the aerodynamics of a small passenger car in an overtaking manoeuvre on the motorway was considered, many years ago, during the 1970's, to be a potential problem for the vehicle aerodynamicist. The concern never became significant as vehicle architecture evolved and car weights increased. The current drive for improved fuel economy is advocating that a considerable reduction in vehicle mass is desirable and therefore it may be time to readdress the significance of the truck passing manoeuvre. A quasi-steady experiment has been undertaken at small model scale to examine the aerodynamic characteristics of a small car in proximity to a large truck. Measurements at yaw were included to crudely simulate the effects of a crosswind. The wind tunnel data is presented and the limitations of the experimental procedure are discussed. An estimate of the increased aerodynamic input on a car in a real world overtaking manoeuvre with relative velocity between the two vehicles is introduced. The data is compared with the steady state yaw characteristics of the car…
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Comparative Analysis of Multiple Powertrain Architectures based on a Novel Optimization Framework

Cranfield Univ.-Ganesh Mohan, Francis Assadian, Stefano Longo
Published 2014-04-01 by SAE International in United States
Identifying the most appropriate powertrain technology for a given vehicle class and duty cycle can be beneficial to further drive down on carbon emissions. However, with a myriad of powertrain architectures that are emerging in the industry, such as those in Electric Vehicles and Hybrid Vehicles, it becomes more challenging to carry out comprehensive comparative analyses across different permutations of powertrain topologies.This has motivated the authors to research on improving the method used to compare different types of powertrain architectures, and develop a tool that can be used by practitioners for this purpose. Literature survey has indicated that whilst there have been many comparisons made between different types of powertrains, such analyses were often carried out by comparing only limited types of architectures at a time. Additionally, many commercially available tools lack the combination of an optimization algorithm with the ability to simulate different combinations of powertrain architectures concurrently to provide a meaningful comparison.In this paper, a new approach is proposed that simultaneously optimizes powertrain architecture selection and component sizing. Results from this investigation have…
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Integrated Vehicle Health Management: Perspectives on an Emerging Field

Cranfield Univ.-Ian K Jennions
  • Book
  • R-405
Published 2011-09-27 by SAE International in United States
Unique and groundbreaking—this highly-anticipated book addresses both basic and advanced concepts critical for the understanding and support of the developing field of Integrated Vehicle Health Management (IVHM). From an initial idea by the SAE IVHM Steering Group, collaboratively written by experts from academia, research and industry, the thirteen chapters within this book represent the collective voice of the most qualified authorities in the field. Highlights of the book include: -a single definition and taxonomy of IVHM, as well as basic principles -the identification of how and where IVHM should be implemented -the commercial value of IVHM -vehicle health management systems engineering -algorithms and their impact on IVHM -IVHM future directions and issues -Case study on IHUMS This book serves as the perfect introduction to IVHM for engineers, executives, academic instructors, and students.
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Low Speed Aerodynamic Study of Full-Scale High-Fidelity Runback Ice Shapes

Cranfield Univ.-Nathalie Alegre, David Hammond
Published 2011-06-13 by SAE International in United States
This study reports aerodynamic properties of two runback ice shapes molded from a mid-span full scale B737 aerofoil leading edge together with a series of simplistic ice shapes of the type sometimes used by aircraft manufacturers to mimic performance loss due to runback ice. The runback ice shapes were taken from a study of runback ice growth which had produced flexible silicone rubber moulds. These moulds were used to produce ice shapes without curvature which, together with the “simplistic” shapes were mounted on flat plates and installed into the Cranfield University 8 by 6 foot wind tunnel. A boundary layer suction system was used to match the wall conditions more closely to what would be anticipated on a real aerofoil. The icing conditions approximate to a hold case with the two shapes representing a 4 and a 10 mm thick runback shape. The aerodynamic tests have been performed with a tunnel speed of 45 m/s. Rakes of pitot tubes were used in various downstream locations to probe the flow field. The aerodynamic data is presented…
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Adaptive Automated Assembly of Wing System Components

Cranfield Univ.-Philip Webb, Celine Michel
Airbus Operations-Amir Kayani, Mike Poad
Published 2010-09-28 by SAE International in United States
A modern aircraft wing contains many complex pipes and ducts which, amongst other functions, form the fuel management and bleed air systems. These parts are often fabricated from thin sheet material using a combination of forming and welding and the manufacturing process is predominantly manual requiring highly skilled labor. Since each wing may only contain one or two of each part type the product volumes are very low, typically a few hundred per year. This means that conventional mass production approaches used in, for example the automotive industry, are not economically viable and the parts are thus disproportionately expensive.The current fabrication process involves splitting the component into parts that can be press formed from sheet, laser trimmed and then manually welded together in a fixture. This process requires a perfect fit between the parts whose quality is reliant on the initial forming process. Problems often occur due to spring-back and stress release during the cutting process resulting in poorly aligned parts and the requirement for manual fettling.The work described in this paper proposes an alternative…
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