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Aneli Bongers - One of the best experts on this subject based on the ideXlab platform.
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learning and forgetting in the jet fighter Aircraft Industry
PLOS ONE, 2017Co-Authors: Aneli BongersAbstract:A recent strategy carried out by the Aircraft Industry to reduce the total cost of the new generation fighters has consisted in the development of a single airframe with different technical and operational specifications. This strategy has been designed to reduce costs in the Research, Design and Development phase with the ultimate objective of reducing the final unit price per Aircraft. This is the case of the F-35 Lightning II, where three versions, with significant differences among them, are produced simultaneously based on a single airframe. Whereas this strategy seems to be useful to cut down pre-production sunk costs, their effects on production costs remain to be studied. This paper shows that this strategy can imply larger costs in the production phase by reducing learning acquisition and hence, the total effect on the final unit price of the Aircraft is indeterminate. Learning curves are estimated based on the flyaway cost for the latest three fighter Aircraft models: The A/F-18E/F Super Hornet, the F-22A Raptor, and the F-35A Lightning II. We find that learning rates for the F-35A are significantly lower (an estimated learning rate of around 9%) than for the other two models (around 14%).
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learning and forgetting in the jet fighter Aircraft Industry
Research Papers in Economics, 2017Co-Authors: Aneli BongersAbstract:A recent strategy carried out by the Aircraft Industry to reduce the total cost of new generation fighter has consisted in the development of a single airframe with different technical and operational specifications. This strategy has been designed to reduce costs in the Research, Design, and Development phase with the aim of reducing the final unitary price of Aircraft. This is the case of the F-35 Lightning II, where three versions, with significant differences among them, are produced simultaneously based on a single airframe. Whereas this strategy seems to be useful to reduce pre-production sunk costs, remains key to study their effects on production costs. This paper shows that this strategy can imply larger costs in the production phase by reducing learning acquisition and hence, the total effect on the final unitary price of the Aircraft is indeterminate. Learning curves are estimated based on the flyaway cost for the latest three fighter Aircraft models: The A/F-18E/F Super Hornet, F-22A Raptor, and the F-35A Lightning II. We find that learning rates for the F-35A are significantly lower (an estimated learning rate around 9%) than for the other two models (around 14%).
Bringmann Philipp - One of the best experts on this subject based on the ideXlab platform.
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Atmospheric pressure plasma jet deposition of Si-based coupling films as surface preparation for structural adhesive bonding inthe Aircraft Industry: Comparison of joint durability after APPJ-CVD and solution derived silane treatments
2016Co-Authors: Bringmann PhilippAbstract:Damages of metallic Aircraft structures that occur during manufacturing, assembly and in service require local repair. Especially with current service-life extensions of ageing Aircraft fleets, the importance of such repair methods is increasing. Typically, the repair of smaller damages on aluminium fuselage or wing skins is done by riveting a patch onto the flawed structure. However, the use of rivets reduces the strength of the structure and promotes fatigue. Joining the patch by adhesive bonding would not only offer more homogenous load distribution and weight savings, but even an increase of structural integrity. Metal adhesive bonding is commonly used in aeronautics, but requires elaborated surface treatments of the adherends, employing hazardous chemicals like chromates, due to the high durability demands. Furthermore, these treatments are usually tank processes that are not suitable for local repairs. Hence, there is a strong need for locally applicable surface preparation methods that allow safe and reliable adhesive bonding of primary Aircraft structures. The aim of this thesis is to assess the – still emerging – method of atmospheric pressure plasma deposition of silicon (Si) containing compounds concerning its suitability as surface preparation for adhesive bonding of aluminium aerostructures. Atmospheric plasma deposition is not yet used in the Aircraft Industry, and the knowledge on functionality of this technology concerning bonding of aluminium parts is limited. Moreover, the durability requirements of the Aircraft Industry greatly exceed the standards in other industries. Hence, special attention is paid to a thorough analysis of the key characteristics of the deposited coupling films and their effectiveness in terms of adhesion promotion as well as joint durability under particularly hostile conditions. In order to do so, the altering mechanisms of the treated joints and the behaviour of the coupling films during accelerated ageing will be investigated in detail for the first time in this thesis. Furthermore, the influence of the aluminium surface pre-treatment (i.e. topography and oxide properties of the substrate) on the overall joint performance after coupling film deposition is thoroughly examined. Based on these findings, the surface preparation is optimised, and a process is developed to achieve maximal joint performance. As alternative local surface treatments prior to adhesive bonding, solution derived deposition of silane and sol-gel films have already been widely investigated and can be considered as reference, even though these techniques are rarely used in civil aeronautics. The knowledge on their effectiveness and capabilities in corrosive atmosphere is still very limited. Therefore, all analyses of degradation mechanisms are conducted for both plasma deposition and wet-chemical reference treatments to reveal the differences and communalities of the two Si-based coupling films. Physical and chemical analysis of the films, the oxides and the interfaces reveal differing, but interdependent failure mechanisms that are inhibited differently by the individual coupling films. Using the optimum deposition parameters, plasma films of only several nanometres in thickness significantly enlarge the corrosion resistance of bonded joints, reaching almost the level of anodising treatments with several micrometres thick oxides and strongly outperforming solution derived silane treatments. However, plasma film performance is found to be largely dependent on the precursor selection. With plasma deposition of 3-glycidoxypropyltrimethoxysilane, which has not been reported before, highest joint stability is achieved. Moreover, it is discovered that the properties of plasma and solution derived silane based films are complementary. It is shown that an optimised combined plasma and wet-chemical treatment process provides even superior resistance to bondline corrosion than state-of-the-art anodising techniques
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Atmospheric pressure plasma jet deposition of Si-based coupling films as surface preparation for structural adhesive bonding in the Aircraft Industry: Comparison of joint durability after APPJ-CVD and solution derived silane treatments
2016Co-Authors: Bringmann PhilippAbstract:Damages of metallic Aircraft structures that occur during manufacturing, assembly and in service require local repair. Especially with current service-life extensions of ageing Aircraft fleets, the importance of such repair methods is increasing. Typically, the repair of smaller damages on aluminium fuselage or wing skins is done by riveting a patch onto the flawed structure. However, the use of rivets reduces the strength of the structure and promotes fatigue. Joining the patch by adhesive bonding would not only offer more homogenous load distribution and weight savings, but even an increase of structural integrity. Metal adhesive bonding is commonly used in aeronautics, but requires elaborated surface treatments of the adherends, employing hazardous chemicals like chromates, due to the high durability demands. Furthermore, these treatments are usually tank processes that are not suitable for local repairs. Hence, there is a strong need for locally applicable surface preparation methods that allow safe and reliable adhesive bonding of primary Aircraft structures. / The aim of this thesis is to assess the – still emerging – method of atmospheric pressure plasma deposition of silicon (Si) containing compounds concerning its suitability as surface preparation for adhesive bonding of aluminium aerostructures. Atmospheric plasma deposition is not yet used in the Aircraft Industry, and the knowledge on functionality of this technology concerning bonding of aluminium parts is limited. / Moreover, the durability requirements of the Aircraft Industry greatly exceed the standards in other industries. Hence, special attention is paid to a thorough analysis of the key characteristics of the deposited coupling films and their effectiveness in terms of adhesion promotion as well as joint durability under particularly hostile conditions. In order to do so, the altering mechanisms of the treated joints and the behaviour of the coupling films during accelerated ageing will be investigated in detail for the first time in this thesis. Furthermore, the influence of the aluminium surface pre-treatment (i.e. topography and oxide properties of the substrate) on the overall joint performance after coupling film deposition is thoroughly examined. Based on these findings, the surface preparation is optimised, and a process is developed to achieve maximal joint performance. / As alternative local surface treatments prior to adhesive bonding, solution derived deposition of silane and sol-gel films have already been widely investigated and can be considered as reference, even though these techniques are rarely used in civil aeronautics. The knowledge on their effectiveness and capabilities in corrosive atmosphere is still very limited. Therefore, all analyses of degradation mechanisms are conducted for both plasma deposition and wet-chemical reference treatments to reveal the differences and communalities of the two Si-based coupling films. Physical and chemical analysis of the films, the oxides and the interfaces reveal differing, but interdependent failure mechanisms that are inhibited differently by the individual coupling films. / Using the optimum deposition parameters, plasma films of only several nanometres in thickness significantly enlarge the corrosion resistance of bonded joints, reaching almost the level of anodising treatments with several micrometres thick oxides and strongly outperforming solution derived silane treatments. However, plasma film performance is found to be largely dependent on the precursor selection. With plasma deposition of 3-glycidoxypropyltrimethoxysilane, which has not been reported before, highest joint stability is achieved. Moreover, it is discovered that the properties of plasma and solution derived silane based films are complementary. It is shown that an optimised combined plasma and wet-chemical treatment process provides even superior resistance to bondline corrosion than state-of-the-art anodising techniques
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Atmospheric pressure plasma jet deposition of Si-based coupling films as surface preparation for structural adhesive bonding in the Aircraft Industry Atmospheric pressure plasma jet deposition of Si-based coupling films as surface preparation for str
2015Co-Authors: Bringmann PhilippAbstract:Damages of metallic Aircraft structures that occur during manufacturing, assembly and in service require local repair. Especially with current service-life extensions of ageing Aircraft fleets, the importance of such repair methods is increasing. Typically, the repair of smaller damages on aluminium fuselage or wing skins is done by riveting a patch onto the flawed structure. However, the use of rivets reduces the strength of the structure and promotes fatigue. Joining the patch by adhesive bonding would not only offer more homogenous load distribution and weight savings, but even an increase of structural integrity. Metal adhesive bonding is commonly used in aeronautics, but requires elaborated surface treatments of the adherends, employing hazardous chemicals like chromates, due to the high durability demands. Furthermore, these treatments are usually tank processes that are not suitable for local repairs. Hence, there is a strong need for locally applicable surface preparation methods that allow safe and reliable adhesive bonding of primary Aircraft structures. The aim of this thesis is to assess the – still emerging – method of atmospheric pressure plasma deposition of silicon (Si) containing compounds concerning its suitability as surface preparation for adhesive bonding of aluminium aerostructures. Atmospheric plasma deposition is not yet used in the Aircraft Industry, and the knowledge on functionality of this technology concerning bonding of aluminium parts is limited. Moreover, the durability requirements of the Aircraft Industry greatly exceed the standards in other industries. Hence, special attention is paid to a thorough analysis of the key characteristics of the deposited coupling films and their effectiveness in terms of adhesion promotion as well as joint durability under particularly hostile conditions. In order to do so, the altering mechanisms of the treated joints and the behaviour of the coupling films during accelerated ageing will be investigated in detail for the first time in this thesis. Furthermore, the influence of the aluminium surface pre-treatment (i.e. topography and oxide properties of the substrate) on the overall joint performance after coupling film deposition is thoroughly examined. Based on these findings, the surface preparation is optimised, and a process is developed to achieve maximal joint performance. As alternative local surface treatments prior to adhesive bonding, solution derived deposition of silane and sol-gel films have already been widely investigated and can be considered as reference, even though these techniques are rarely used in civil aeronautics. The knowledge on their effectiveness and capabilities in corrosive atmosphere is still very limited. Therefore, all analyses of degradation mechanisms are conducted for both plasma deposition and wet-chemical reference treatments to reveal the differences and communalities of the two Si-based coupling films. Physical and chemical analysis of the films, the oxides and the interfaces reveal differing, but interdependent failure mechanisms that are inhibited differently by the individual coupling films. Using the optimum deposition parameters, plasma films of only several nanometres in thickness significantly enlarge the corrosion resistance of bonded joints, reaching almost the level of anodising treatments with several micrometres thick oxides and strongly outperforming solution derived silane treatments. However, plasma film performance is found to be largely dependent on the precursor selection. With plasma deposition of 3-glycidoxypropyltrimethoxysilane, which has not been reported before, highest joint stability is achieved. Moreover, it is discovered that the properties of plasma and solution derived silane based films are complementary. It is shown that an optimised combined plasma and wet-chemical treatment process provides even superior resistance to bondline corrosion than state-of-the-art anodising techniques
W F Stanley - One of the best experts on this subject based on the ideXlab platform.
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an experimental study of bolt hole clearance effects in double lap multi bolt composite joints
Composite Structures, 2005Co-Authors: V P Lawlor, M A Mccarthy, W F StanleyAbstract:Abstract An experimental study on the effects of variable bolt–hole clearance in double-lap, multi-bolt joints is presented. Joints with different clearances in each hole have been tested and the effects on load distribution, quasi-static strength, fatigue life and failure modes are reported. Strain gauges have been used for measuring load distribution and specialised jigs have been used for positioning the bolts in the holes and drilling the joints. The clearances examined ranged from neat-fit to clearances slightly larger than those allowed in the Aircraft Industry. Clearance has been found to have major effects on the load distribution; no effect on ultimate quasi-static strength but significant effect on failure initiation load; and quite significant effects on fatigue life.
Jeanchristophe Wahl - One of the best experts on this subject based on the ideXlab platform.
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an analytical model for the prediction of load distribution in multi bolt composite joints including hole location errors
Composite Structures, 2014Co-Authors: Julie Lecomte, Christophe Bois, H Wargnier, Jeanchristophe WahlAbstract:Abstract In the Aircraft Industry, the method for designing metal-composite joints is mainly based on conservative metallic calculation rules and on applying high safety factors. The reason is that the influence of errors due to manufacturing is not well-known, and few studies deal with this issue. Here, an analytical model is developed to evaluate load distribution in an aluminium-composite double-lap joint, in the presence of clearance and hole-location errors. The model also includes the nonlinear behaviour of the bolt implied by bearing degradation. The analytical model is validated by comparing results obtained by finite element analysis and experiments. Finally, an industrial use of the analytical model is presented.
Elyse Golob - One of the best experts on this subject based on the ideXlab platform.
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IMPACT OF DEREGULATION ON INVESTMENT AND PRODUCTION STRATEGIES IN THE COMMERCIAL Aircraft Industry
Transportation Research Record, 1995Co-Authors: Elyse GolobAbstract:The impact of the Airline Deregulation Act of 1978 on the U.S. Aircraft manufacturing Industry is investigated. The ways in which the removal of fare and route restrictions precipitated a restructuring of the investment and production strategies of the two major domestic airframe manufacturers are explained. On the basis of a series of interviews with informants in the airline and Aircraft manufacturing industries, it is concluded that deregulation has affected the commercial Aircraft Industry in four significant ways : (a) fleet analysis procedures were transformed following deregulation, (b) the emergent hub-and-spoke system precipitated major fleet reconfigurations, (c) there was a rise in manufacturer and institutional financing and leasing agreements, and (d) airlines were saddled with aging and multiple-model fleets. Manufacturers have responded to these developments by assuming an increased share of the risks associated with Aircraft acquisition, incorporating customer concerns in Aircraft design, and reducing capacity while increasing productivity.