DAEDALOS

Dynamics in Aircraft Engineering Design and Analysis for Light Optimized Structures

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 Obiettivo del progetto (Objective)

'Today’s design and certification procedures of aircrafts are mainly based on conservative static loading which leads to additional weight and, potentially, to a structurally unsafe aircraft. The overall objective of the DAEDALOS project is to develop methods and procedures to determine dynamical loads considering the effects of dynamic buckling, material damping and mechanical hysteresis during aircraft service. Use of advanced analysis and design principles from DAEDALOS will partly remove the uncertainty and the conservatism of today’s design and certification procedures. DAEDALOS work will hence form the basis for improved common design practices by: 1. Determining accurate dynamic load spectra to be used for structural sizing. 2. Reducing the added weight of aircraft structural components due to conservative design in compliance with quasi-static loads by using more realistic equivalent dynamic loads. This goal will be achieved through improved introduction of the structure damping capacity and detailed analysis. 3. Increasing structural safety using more realistic loading scenarios. 4. Establishing new procedures for the definition of loads to be used during aircraft design and certification by authorities.'

Introduzione (Teaser)

The European aircraft industry and transport policy are demanding safer and greener transport systems. EU researchers in the DAEDALOS project have taken an innovative design approach for aerospace structures that will result in aircraft weight reduction with corresponding fuel saving and lower emissions and operating costs.

Descrizione progetto (Article)

Current design standards based on conservative static loading often lead to additional and unnecessary weight. Without adequate understanding and consideration of dynamic loads, resulting designs may even be unsafe. The 'Dynamics in aircraft engineering design and analysis for light optimized structures' (http://www.daedalos-fp7.eu/ (DAEDALOS)) project has characterised dynamic loads during aircraft service. Incorporation of effects of material damping, dynamic buckling and mechanical hysteresis stand to remove the uncertainty and conservatism of present-day aircraft certification procedures.

Conventional design practice considers the fuselage as a beam on which a load is statically applied. It is a highly simplified model assuming that no energy is absorbed from the fuselage by the stringer/frame/skin constructions. It assumes that the full load propagates along the fuselage without attenuation from structural damping.

This is not the case in the real system. In addition, dynamic buckling can be much greater than static buckling, meaning that the fuselage could theoretically absorb more energy without breaking under a higher load than is predicted in the static case. The end result of these assumptions is a heavier design that may not address real-life dynamic loading conditions.

DAEDALOS developed a mid-size business jet model for the analysis. The team developed full finite element and hybrid models at various scales. Various methods for evaluating structural energy dissipation via damping were developed and implemented. These included a strain energy method, as well as quasi-linear viscoelastic material and generalised Maxwell viscous material damping models.

A rigorous campaign of experimental testing supported model development. The team evaluated materials damping of an aluminium alloy and two carbon-epoxy composites at coupon level using a variety of techniques. Panels and shells representative of typical components were also tested subjected to static and dynamic loads. Furthermore, the components were assessed in terms of weight benefits.

Through its advanced models, simulation tools and databases, the DAEDALOS project established a scientific basis for new aircraft design and certification standards reflecting energy dissipation during dynamic loading. Dynamic analysis is part of the design process in many industries and DAEDALOS deliverables could therefore be appropriate in a wide range of applications and fields.