The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Rhys Jones - One of the best experts on this subject based on the ideXlab platform.
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Additive metal solutions to aircraft skin corrosion
The Aeronautical Journal, 2020Co-Authors: Neil Matthews, Rhys Jones, Daren Peng, Nam Phan, Trung NguyenAbstract:ABSTRACTThis paper focuses on the problem of skin corrosion on the upper wing surfaces of rib-stiffened aircraft. For maritime and military transport aircraft this often results in multiple co-located repairs. The common approach to corrosion damage in operational aircraft is to blend out the corrosion and rivet a mechanical doubler over the region. In particular this paper describes the results of a combined numerical and experimental investigation into the ability of the additive metal technology, Supersonic Particle Deposition (SPD), to restore the load-carrying capacity of rib-stiffened wing planks with simulated skin corrosion. The experimental results reveal that unrepaired skin corrosion can result in failure by yielding. The experimental results also reveal that SPD repairs to skin corrosion can restore the stress field in the structure, and can ensure that the load-carrying capability of the repaired structure is above proof load.
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Applications of SPD to enhance the structural integrity of corroded airframes
Aircraft Sustainment and Repair, 2018Co-Authors: Rhys Jones, Neil Matthews, Daren Peng, Nam Phan, Trung NguyenAbstract:Abstract In the past decades, particularly since the Aloha Airlines (AA243) in 1989, corrosion has become one of the primary considerations in both military and commercial aircraft. Numerous authors have noted that corrosion can impact heavily on the economics, maintenance and safety of aircraft fleets. A number of different types of corrosion have been detected on aircraft structural aluminium alloys with exfoliation, pitting, intergranular corrosion and stress corrosion cracking being the prominent types of corrosion generally occurring in structural components exposed to corrosive environments. The additive metal technology of Supersonic Particle Deposition offers an effective methodolgy of repairing such damage.
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Repair of Multisite Damage in Civil Transport Aircraft: An Example of the Damage-Tolerant Design of Composite Repairs
Aircraft Sustainment and Repair, 2018Co-Authors: Lorrie Molent, Rhys JonesAbstract:Abstract This chapter illustrates how the damage-tolerant design approach discussed in Chapter 8 can be used to design repairs to multisite damage in civil transport fuselage lap joints. To this end the chapter discusses the results of the associated laboratory test programme and the subsequence flight demonstrator programmes. This chapter is complimented by the work presented in Chapter 11 which further illustrates how this damage-tolerant design approach was used to design composite repairs to DC-10 and DC11 aircraft. The work presented in this chapter is complimented by that presented in Chapter 17 which illustrates how Supersonic Particle Deposition (SPD), which is an additive metal technology that is also referred to as cold spray, when used in conjunction with the standard practice of using a sealant to stop the environment entering the joint via the gap between the mating fuselage skins, can seal the fasteners and thereby alleviate corrosion damage and consequently extend the time to crack initiation at the joint so that the limit of validity (LOV) is not degraded by corrosion.
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Crack growth from naturally occurring material discontinuities
Aircraft Sustainment and Repair, 2018Co-Authors: Rhys Jones, Daren Peng, Alison J. McmillanAbstract:All repairs to airframes now need to be assessed as to their effect on the damage tolerance the aircraft. To this end this chapter first discusses difference between the analysis tools needed for ab initio design and aircraft sustainment. It is shown that using small or physically short-crack da/dN versus Δ K data results in reduced through life costs and increased aircraft availability. The tests procedures needed to validate composite or Supersonic Particle Deposition (SPD), repairs to operational aircraft are also discussed as is their relationship to the ASTM fatigue test standard E647-13a. This leads to an examination of the problem of crack growth from small naturally occurring material discontinuities under operational load spectra. A range of tools are available to account for crack growth in operational aircraft and several such tools are discussed, viz.: cycle-by-cycle analysis; the USAF characteristic K approach, etc. Specific attention is paid to the growth of lead cracks in operational aircraft which are shown to exhibit near exponential crack growth and to essentially have a cubic dependency on stress. It is shown that cracks growing in composite repairs exhibit the same crack length and stress dependency. This finding is then linked to current approaches which use the cubic rule to assess repairs to RAAF aircraft.
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a study into the ability of spd to restore the buckling strength and modes of rib stiffened panels with simulated stress corrosion cracks
International Journal of Structural Integrity, 2017Co-Authors: Rhys Jones, Neil Matthews, Daren Peng, Nicholas OrchowskiAbstract:Purpose The purpose of this paper is to describe the results of a combined numerical and experimental study into the ability of Supersonic Particle Deposition (SPD) to restore the load carrying capacity of rib stiffened wing planks with simulated stress corrosion cracking (SCC). Design/methodology/approach In this context the experimental results reveal that SCC can result in a dramatic reduction in the load carrying capacity of the structure and catastrophic failure via cracking that tears the length of the structure through buckling. A combined numerical and experimental study then reveals how this reduction, in the load carrying capacity can be overcome by using SPD. Findings This paper is the first to show that SPD can be used to restore the load carrying capacity of rib stiffened structures with SCC. It also shows that SPD repairs can be designed to have only a minimal effect on the local stiffness and hence on the load path. However, care should be taken to ensure that the design is such that premature failure of the SPD does not occur. Originality/value This is the first paper to show that a thin layer of SPD deposited 7,075 aluminium alloy powder on either side of the SCC-simulated stiffener has the potential to restore the load carrying capability of a rib stiffened structure. As such it represents an important first step into establishing the potential for SPD to restore the buckling strength of rib stiffened wing panels containing SCC.
Neil Matthews - One of the best experts on this subject based on the ideXlab platform.
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Additive metal solutions to aircraft skin corrosion
The Aeronautical Journal, 2020Co-Authors: Neil Matthews, Rhys Jones, Daren Peng, Nam Phan, Trung NguyenAbstract:ABSTRACTThis paper focuses on the problem of skin corrosion on the upper wing surfaces of rib-stiffened aircraft. For maritime and military transport aircraft this often results in multiple co-located repairs. The common approach to corrosion damage in operational aircraft is to blend out the corrosion and rivet a mechanical doubler over the region. In particular this paper describes the results of a combined numerical and experimental investigation into the ability of the additive metal technology, Supersonic Particle Deposition (SPD), to restore the load-carrying capacity of rib-stiffened wing planks with simulated skin corrosion. The experimental results reveal that unrepaired skin corrosion can result in failure by yielding. The experimental results also reveal that SPD repairs to skin corrosion can restore the stress field in the structure, and can ensure that the load-carrying capability of the repaired structure is above proof load.
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Applications of SPD to enhance the structural integrity of corroded airframes
Aircraft Sustainment and Repair, 2018Co-Authors: Rhys Jones, Neil Matthews, Daren Peng, Nam Phan, Trung NguyenAbstract:Abstract In the past decades, particularly since the Aloha Airlines (AA243) in 1989, corrosion has become one of the primary considerations in both military and commercial aircraft. Numerous authors have noted that corrosion can impact heavily on the economics, maintenance and safety of aircraft fleets. A number of different types of corrosion have been detected on aircraft structural aluminium alloys with exfoliation, pitting, intergranular corrosion and stress corrosion cracking being the prominent types of corrosion generally occurring in structural components exposed to corrosive environments. The additive metal technology of Supersonic Particle Deposition offers an effective methodolgy of repairing such damage.
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Additive Metal Technologies for Aerospace Sustainment
Aircraft Sustainment and Repair, 2018Co-Authors: Neil MatthewsAbstract:Abstract This chapter presents how two additive metal technologies namely Supersonic Particle Deposition (SPD) and laser additive Deposition (LAD) are being used in the sustainment of aerospace vehicles to reduce the cost of ownership and increase operational availability. In particular, this chapter outlines the selection of SPD and LAD, the certification and implementation strategies as well as current applications and the potential future applications of these technologies.
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Introduction to Supersonic Particle Deposition
Aircraft Sustainment and Repair, 2017Co-Authors: Victor K. Champagne, Neil MatthewsAbstract:Abstract This chapter will introduce Supersonic Particle Deposition and how it can be used for dimensional restoration. It will also attempt to present a discussion on the advantages and potential of SPD.
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a study into the ability of spd to restore the buckling strength and modes of rib stiffened panels with simulated stress corrosion cracks
International Journal of Structural Integrity, 2017Co-Authors: Rhys Jones, Neil Matthews, Daren Peng, Nicholas OrchowskiAbstract:Purpose The purpose of this paper is to describe the results of a combined numerical and experimental study into the ability of Supersonic Particle Deposition (SPD) to restore the load carrying capacity of rib stiffened wing planks with simulated stress corrosion cracking (SCC). Design/methodology/approach In this context the experimental results reveal that SCC can result in a dramatic reduction in the load carrying capacity of the structure and catastrophic failure via cracking that tears the length of the structure through buckling. A combined numerical and experimental study then reveals how this reduction, in the load carrying capacity can be overcome by using SPD. Findings This paper is the first to show that SPD can be used to restore the load carrying capacity of rib stiffened structures with SCC. It also shows that SPD repairs can be designed to have only a minimal effect on the local stiffness and hence on the load path. However, care should be taken to ensure that the design is such that premature failure of the SPD does not occur. Originality/value This is the first paper to show that a thin layer of SPD deposited 7,075 aluminium alloy powder on either side of the SCC-simulated stiffener has the potential to restore the load carrying capability of a rib stiffened structure. As such it represents an important first step into establishing the potential for SPD to restore the buckling strength of rib stiffened wing panels containing SCC.
Dinaz Zenobia Tamboli - One of the best experts on this subject based on the ideXlab platform.
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On the Growth of Cracks from Small Naturally Occurring Material Discontinuities
2017Co-Authors: Dinaz Zenobia TamboliAbstract:The objective of this thesis is to analyse data available in the open literature and conduct experimental test programs to develop a robust and consistent mechanistic model that can be used to predict the growth of fatigue cracks in high performance combat aircraft. Military aircraft worldwide are being operated close to or beyond their design lives. This, in part, is driven by fiscal pressures and supported by vast improvements in structural integrity management programs which include advanced non-destructive inspection techniques, new fatigue damage assessment tools and radical repair techniques. The risk of failure due to fatigue, however, remains a key concern for most aircraft operators. This is because of differences in the fatigue prediction tools used in the design stage and the problems encountered in service. In particular, the short crack anomaly appears to be a major reason for this difference. To this end, this thesis seeks to develop a model which unifies the growth of both long and short cracks because service experience has shown that for any damage tolerant analysis, the overall fatigue life should be an amalgam of both long and short fatigue cracks. Moreover, it is now well known that the majority of the fatigue life of aircraft structures is spent in the short crack regime which makes it even more imperative to address this issue. Solving the short crack anomaly, however, comes with its own set of challenges. There is a large scatter associated with the growth of short cracks. This scatter has been observed in cracks growing in specimens made from the same material to exactly the same specifications under constant amplitude loading, variable amplitude loading, representative flight spectra and civil transport spectra. For ongoing risk management of the aging fleet it is imperative that the model used in any damage tolerance analysis be able to capture this scatter. Therefore, this thesis also seeks to investigate the robustness of the chosen mechanistic model in capturing the variability in crack growth under constant amplitude loading, variable amplitude loading, a standard fighter aircraft spectrum (FALSTAFF) and a civil transport spectrum (miniTWIST). Since fatigue life prediction requires an amalgam of short and long crack growth curves, it is important not only to address the variability in short cracks but also those observed in long cracks under variable amplitude loading and representative flight spectra. Therefore, this thesis also seeks to address this challenge by using experimental data available in open literature and the USAF Characteristic K approach to capture the variability in long cracks. For all the issues detailed above, it was found that using the Hartman-Schijve crack growth equation, the short crack anomaly and the variability observed in both long and short cracks were captured fairly well. Problems with aircraft are not limited to fatigue cracking alone. Corrosion plays an equally dominant role in challenges associated with the life of aircraft in service. While most corrosion related studies thus far have focussed predominantly on the interaction of corrosion and fatigue, a new hypothesis has been proposed more recently. Some studies have shown that corrosion is a ground-based phenomenon while fatigue cracking occurs in flight and these two phenomena are decoupled. To investigate this hypothesis, an experimental test program was carried out and is detailed in this thesis. The resulting crack growth curve was measured via quantitative fractography and analysed by the Hartman-Schijve equation. The experimental data revealed that corrosion on ground does not appear to have a significant influence on fatigue cracking in flight. It should be noted, however, that this hypothesis applies only to combat aircraft which fly at high altitudes where the air is cold and dry. For maritime aircraft, which spend extended periods of time flying close to the sea in a humid environment, this may not hold. This decoupling of fatigue and environment is only applicable to pitting corrosion. There are many other forms of corrosion like exfoliation, intergranular, stress corrosion cracking etc. that still play a major role in compromising the life of aircraft. It is therefore important to address these when dealing with the problems plaguing aging aircraft. A secondary focus was thus given to using Supersonic Particle Deposition (SPD) to seal fastener holes in lap joints, thereby preventing further environmental ingress. To check the durability of SPD doublers on service aircraft, 12 SPD doublers were applied to an ex-service F/A-18 centre barrel and tested to more than 3 times its average lifetime. Non-destructive inspection (NDI) of these doublers was performed at regular intervals and no disbonding or delamination was observed even after the centre barrel had been fatigued for over 15,000 flight hours. It is hoped that the work detailed in this thesis contributes to the overall fatigue management practices of combat aircraft
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Supersonic Particle Deposition as a means for enhancing the structural integrity of aircraft structures
International Journal of Fatigue, 2014Co-Authors: Rhys Jones, Neil Matthews, Lorrie Molent, Simon Barter, Dinaz Zenobia TamboliAbstract:Abstract The paper presents the results of experimental studies into the application of Supersonic Particle Deposition (SPD) for repairing and enhancing the airworthiness and integrity of aging aircraft structures. Presented are the results of coupon tests on the application of SPD doublers to mechanically fastened joints and to simulated corrosion damage tested under constant amplitude fatigue loads. These successful tests are then supported by an application to an F/A-18 Hornet wing attachment centre barrel laboratory test article.
Victor K. Champagne - One of the best experts on this subject based on the ideXlab platform.
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Introduction to Supersonic Particle Deposition
Aircraft Sustainment and Repair, 2017Co-Authors: Victor K. Champagne, Neil MatthewsAbstract:Abstract This chapter will introduce Supersonic Particle Deposition and how it can be used for dimensional restoration. It will also attempt to present a discussion on the advantages and potential of SPD.
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Supersonic Particle Deposition for Repair and Corrosion Protection of Mg Gearboxes
2009Co-Authors: Brian M Gabriel, Phillip F. Leyman, Dennis J. Helfritch, Victor K. ChampagneAbstract:Abstract : To demonstrate and qualify SPD aluminum alloy coatings as a cost-effective, ESOH-acceptable technology to provide surface protection and a repair/rebuild methodology for Mg alloy components on Army and Navy helicopters and advanced fixed-wing aircraft such as the Joint Strike Fighter.
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Cold Spray Process Development for the Reclamation of the Apache Helicopter Mast Support
2009Co-Authors: P. F. Leyman, Victor K. ChampagneAbstract:Abstract : The U.S. Army Research Laboratory at Aberdeen Proving Ground, MD, has developed a novel process for repairing and rebuilding damaged aluminum components using Supersonic Particle Deposition, commonly referred to as cold spray. A Centerline Model No. SSM-P3300 Portable Cold Spray Deposition System was used to deposit a highly adherent, dense aluminum composite material to repair corrosion damage pits and rebuild the snap ring groove and gear teeth on the mast support on an Army helicopter. ARL performed microstructural analysis as well as adhesion, fatigue, and corrosion tests to evaluate the characteristics of the cold spray aluminum composite coatings. The cold spray deposited material was subsequently machined using conventional machining tools to dimensionally restore the component to its original condition. Final testing and approval for implementation of this repair procedure is in progress.
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The effects of gas and metal characteristics on sprayed metal coatings
Modelling and Simulation in Materials Science and Engineering, 2005Co-Authors: Victor K. Champagne, Phillip F. Leyman, Dennis J. Helfritch, Robert Lempicki, Scott M. GrendahlAbstract:Supersonic Particle Deposition (also known as cold spray) is a surface coating process whereby metal Particles are accelerated to Supersonic speeds while entrained in nozzle gas flow and are subsequently deposited by impact onto a surface. Particle velocity is critical for optimal Deposition efficiency and coating quality, and several parameters, including gas conditions, Particle characteristics and nozzle geometry affect Particle velocity. This study investigates the relationship between Particle velocity and coating quality and investigates how nozzle design influences Particle velocity. Performance is described through modelling and verified by direct velocity measurements.
Susan Pitt - One of the best experts on this subject based on the ideXlab platform.
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on the use of Supersonic Particle Deposition to restore the structural integrity of damaged aircraft structures
International Journal of Fatigue, 2011Co-Authors: Rhys Jones, Neil Matthews, K. Cairns, C A Rodopoulos, Susan PittAbstract:The paper presents a preliminary experimental study and an analysis of the potential application of Supersonic Particle Deposition (SPD) for repairing and restoring the airworthiness and functionality of aging aircraft structures. In this work the fatigue performances of cracked metallic structures with a SPD doubler/patch under constant amplitude loading were monitored using infra-red thermography, whereas for the baseline specimen test the crack length was monitored using digital cameras. In all the cases the experimental data revealed that the baseline specimens, i.e. without an SPD patch, accrued damage more rapidly and that crack growth was significantly greater than the corresponding SPD patched panels. In the majority of tests cases the patched panels showed little evidence of damage/crack growth. A prediction of the fatigue performance of an SPD patched single edge notch coupon is made using SIF values calculated via an approximate analysis and the resultant crack length history is in good agreement with experimental data. Weight function solutions for SPD repairs to centre cracked panels are also developed and validated via three dimensional finite element analysis. The paper concludes that SPD is effective in containing damage and that the proposed analytical solution is good first approximation that can be used to calculate the associated SIF and thereby account for the effect of an SPD patch on crack growth.
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Application of Supersonic Particle Deposition for Restoring the Structural Integrity of Damaged Aircraft Structures
2010Co-Authors: Rhys Jones, Neil Matthews, Mukunthan Krishnapillai, K. Cairns, Susan PittAbstract:The June 2007 Report to Congress by the Under Secretary of the Department of Defence (Acquisition, Technology and Logistics) outlined the need for research into repair processes that could restore corroded materials to an acceptable level of structural integrity and functionality. To this end the present paper outlines a preliminary study into the potential of Supersonic Particle Deposition (SPD), also known as cold spray, for repairing and restoring the airworthiness and functionality of aging aircraft.