The paper addresses the use of sensitivities for flight loads analysis in pre-design with deeper consideration of gradients. A possible way of obtaining them from an implementation of the equations of motion by means of automatic differentiation and the embedding in an available framework will be discussed. An example with parametrized inaccuracies in the aerodynamic lift distribution shows that the use of automatic differentiation is a feasible and promising approach. In this work we have discussed the need for sensitivities and possible ways of obtaining them. Ideas how sensitivities, i.e. gradients with respect to corresponding parameters, can be generated and implemented into an existing framework for loads calculation were presented. Preliminary results of an experiment show the feasibility of obtaining sensitivities in the sense of gradients by the tools of automatic differentiation. It was shown that the results obtained by divided differences may depend strongly on the size of the used difference and can hence lead to misleading results. But even though it sounds charming to have a derivative exact down to machine precision for some applications it might still be useful to work with divided differences, since they reflect the behaviour of loads due to a parameter in the vicinity of the solution as well. Still a comparison with an exact derivative may validate the used difference. For more than a few parameters the discussion about visualization suggests that stochastic methods are inevitable to give sensible measures of risks due to the collection of parameters as a whole. Here as well the tools of automatic differentiation can give useful approaches as described in further papers.


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    Title :

    Use of automatic differentiation for sensitivity analysis of flight loads


    Additional title:

    Verwendung automatischer Differenzierung für die Sensitivitätsanalyse von Flugbelastungen


    Contributors:


    Publication date :

    2007


    Size :

    8 Seiten, 3 Bilder, 10 Quellen




    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English





    Aeroelastic sensitivity analysis of wings using automatic differentiation

    Issac, J.C. / Kapania, R.K. | Tema Archive | 1997



    Aeroelastic Sensitivity Analysis of Wings Using Automatic Differentiation

    Issac, J. / Kapania, R. / American Institute of Aeronautics and Astronautics et al. | British Library Conference Proceedings | 1996