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  • 1.
    Al-anbagi, Ali
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Khalil, Dani
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Utformning avlandningsbanors överbyggnad med hänsyn till slitlagrets bärförmåga2020Independent thesis Basic level (professional degree), 180 HE creditsStudent thesis
    Abstract [en]

    n this study, the design of the runway structure of the runways is studied in order tocompare different material compositions in the pavement. This is done with the helpof a survey, the program FAARFIELD and peer reviewed studies. Generally, thereare two different types of road structures in an airfield, rigid and flexible (concreteand asphalt). The result obtained shows the difference between the differentdimensions and the material content of the different types of road structures, whenthey are loaded with either heavy or light aircraft models. These results are based ona design period that has been selected for 20 years. In contrast, the stiffness of theconcrete was much higher than the asphalt stiffness, which means that it is better touse concrete in large commercial airports. According to the CDF diagram (thediagram showing whether the structural design conditions are met), the damagecaused by the aircraft is approximately at the same location on the runway for bothsuperstructures, it also means that flexible superstructure maintenance needs to bedone more often, compared to rigid superstructures. The fact that the asphalt has alower modulus of elasticity than the concrete is also a reason why maintenance forflexible superstructures needs to be done more often. However, when the roadstructures became heavily loaded, the total demanding thickness for the rigid roadstructure is calculated to be 760 mm and for the flexible road structure 710 mm.

  • 2.
    Chen, Yousheng
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Nasrabadi, Vahid
    Chalmers.
    Linderholt, Andreas
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Abrahamsson, Thomas
    Chalmers.
    Model calibration of locally nonlinear structures using information from sub and super harmonic responses2012In: International Conference on Noise and Vibration Engineering 2012 (ISMA 2012): Proceedings of a meeting held 17-19 September 2012, Leuven, Belgium. Including USD 2012 / [ed] P. Sas, S. Jonckheere & D. Moens, Leuven: Katholieke Universiteit Leuven, Department of Mechanical Engineering , 2012, p. 2451-2464Conference paper (Other academic)
    Abstract [en]

    Large linear finite element models are commonly used in industry to represent global structural behavior and such models are often validated by use of data from vibrational tests. The validated models serve to predict the structural responses due to dynamic loads. Hence, it is important to have models that are able to represent the structural dynamics within the given operating envelope. When test data show proof of non linear behavior, a linear model may not be able to represent the dynamics well enough and thus a modification of the model is required. The main part of the structure may have a linear characteristic whereas localized physical processes can be sources of the observed nonlinearities. Model calibration of such locally nonlinear structures is studied in this paper. Specifically, the calibration process including the selection of appropriate data to be used for calibration of the model parameters chosen is treated. Here, synthetic test data stemming from a model of the Ecole Centrale de Lyon (ECL) nonlinear benchmark are used.

  • 3.
    Gustafsson, Pär
    et al.
    Saab Aeronautics.
    Linderholt, Andreas
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    A Study of the Accuracy of Ground Vibration Test Data Using a Replica of the GARTEUR SM-AG19 Testbed Structure2016In: Proceedings of the 30th Congress of the International Council of the Aeronautical Sciences / [ed] The International Council of the Aeronautical Sciences, Bonn: International Council of the Aeoronautical Sciences , 2016Conference paper (Other academic)
    Abstract [en]

    Ground Vibration Tests have been performed on a replica of the Group for Aeronautical Research and Technology in Europe (GARTEUR) testbed structure SM-AG19. The aim of the Ground Vibration Tests was to study the impact on modal data stemming from the test data, from the boundary conditions used to mimic a free-free condition. For the tests an air-spring support system was designed with the aim to give a behaviour that is in resemblance with the behaviour of real aircraft test conditions.

    To eliminate a potential, unwanted, impact on the test results generated by the wing to fuselage interface as it was designed for the original structure (SM-AG19), a deviation from the original interface has been made on the structure for this particular study.

  • 4.
    Klomp, Rolf
    et al.
    Delft University of Technology, The Netherlands.
    Borst, Clark
    Delft University of Technology, The Netherlands.
    Mulder, Max
    Delft University of Technology, The Netherlands.
    Praetorius, Gesa
    Chalmers University of Technology.
    Ecological interface design: Control space robustness in future trajectory-based Air Traffic control decision support2014In: 2014 IEEE International Conference on Systems, Man, and Cybernetics (SMC): October 5-8, 2014 San Diego, CA, USA, IEEE conference proceedings, 2014, p. 329-334Conference paper (Refereed)
    Abstract [en]

    Abstract:The current evolution of the Air Traffic Management system towards trajectory-based operations is foreseen to bring large changes to the work domain of the Air Traffic Controller. Although this new form of Air Traffic Control leans heavily on the introduction of advanced automation, the general consensus is that the human must remain actively involved in the decision-making loop, and retain the ultimate responsibility for the safety of operations. These responsibilities, together with the complexities of the new task, require the development of innovative decision support tools. In previous research, and following the principles of Ecological Interface Design, a constraint-based decision support tool has been developed for the task of strategic trajectory manipulation. Rather than presenting discrete optimized solutions to the controller, this Travel Space Representation visualizes the constraints for safe control in the form of a set of `go' and `no go' areas. A validation experiment demonstrated that when using this tool, controllers sometimes opted for controlling close to the boundaries of safe control, or for resolutions in narrow control spaces. These results gave rise to concern that such a representation could actually work against the flexibility of the system to cope with inherent system variability. In this study, a metric and two measures have been developed in order to quantify and compare trajectory-based robustness to probabilistic disturbances. A batch-analysis has been performed to investigate how these measures vary for a crossing pair of aircraft under various geometry. Results show that the metric captures additional information which is currently not represented in the tool. When visualized to the controller, this could support them to choose more robust control strategies.

  • 5.
    Klomp, Rolf
    et al.
    Delft University of Technology, The Netherlands.
    Borst, Clark
    Delft University of Technology, The Netherlands.
    Mulder, Max
    Delft University of Technology, The Netherlands.
    Praetorius, Gesa
    Chalmers University of Technology.
    Mooij, Martijn
    Thales Research and Technology Netherlands, The Netherlands.
    Nieuwenhuisen, Dennis
    National Aerospace Laboratory NLR, The Netherlands.
    Experimental Evaluation of a Joint Cognitive System for 4D Trajectory Management2013In: Proceedings of the SESAR Innovation Days (2013) / [ed] Dirk Schaefer, Brussels: Eurocontrol, 2013, p. 1-7Conference paper (Refereed)
    Abstract [en]

    Effective joint human-automation coordination is essential in order to support the central role of the human operator in foreseen future trajectory-based air traffic operations. The SESAR WP-E project C-SHARE aims to achieve this by taking a Cognitive Systems Engineering approach, based upon accomplishing joint human and automation cognition through a shared representation of 4D-trajectory management. In foregoing research, a work domain model and a joint humanmachine interface has been developed to support the human operator in the task of en-route 4D trajectory re-planning. This paper presents the findings of two experiments that aimed to determine the effect of both the initial level of traffic orderliness (i.e., structured versus unstructured traffic) and the scale of perturbations acting upon the airspace (e.g., number of conflicts and restricted areas) on the overall effectiveness of such a system. The findings of the experimental evaluation show that the CSHARE approach to joint human-automation coordination in perturbation management is promising. Further, the experiment subjects accepted the tool and found it supportive for the task at hand, resulting in a manageable degree of workload during all experiment scenarios.

  • 6.
    Linderholt, Andreas
    et al.
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Chen, Yousheng
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Abrahamsson, Thomas
    Chalmers University of Technology.
    Time Domain Dynamic Simulations of Locally Nonlinear Large-Scale Systems2016In: Presented at Aerospace technology congress: The Swedish Aeronautics Congress in a Globaised world, October 11-12, 2016, 2016Conference paper (Other academic)
    Abstract [en]

    In practice, most mechanical systems show nonlinear characteristics within the operational envelope. However, the nonlinearities are often caused by local phenomena and many mechanical systems can be well represented by a linear model enriched with local nonlinearities. Conventional nonlinear response simulations are often computationally intensive; the problem which becomes more severe when large-scale nonlinear systems are concerned. Thus, there is a need to further develop efficient simulation techniques. In this work, an efficient simulation method for large-scale systems with local nonlinearities is proposed. The method is formulated in a state-space form and the simulations are done in the Matlab environment. The nonlinear system is divided into a linearized system and a nonlinear part represented as external nonlinear forces acting on the linear system; thus taking advantage in the computationally superiority in the locally nonlinear system description compared to a generally nonlinear counterpart. The triangular-order hold exponential integrator is used to obtain a discrete state-space form. To shorten the simulation time additionally, auxiliary matrices, similarity transformation and compiled C-codes (mex) to be used for the time integration are studied. Comparisons of the efficiency and accuracy of the proposed method in relation to simulations using the ODE45 solver in Matlab and MSC Nastran are demonstrated on numerical examples of different model sizes.

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