Within the EU project ALCAS (Advanced Low Cost Aircraft Structures), co- funded by Airbus UK, a main landing gear fitting is developed and manufactured in carbon fiber reinforced plastics by EADS Innovations Works. Compact and highly loaded composite components experience extensive transverse shear stress concentrations in areas of load introduction and curved sections. Standard 3D multilayered composite brick elements, supplied by the software package MSC Marc/ Mentat, are employed to analyze Ultra Thick Laminates (UTL). For the purpose of validation several full-scale components with T-cross section are tested with thicknesses ranging from 60-90mm. In a first approach single non interactive failure criteria are used due to the uncertainty of out of plane material properties. Despite the fact that the used element type provides a simple mean of modelling and analyzing UTL, it is found that the element formulation strictly limits the accuracy of transverse shear stress prediction. The quadratic or even linear approximation of in plane displacements does not account for the irregular shear distribution in thickness direction. Global deformations of the geometry can however be calculated with good results. Most failure modes experienced, are found to be dominated by transverse shear or out of plane peeling stresses. Particularly in regions close to the load introduction. For the analysis of the final landing gear fitting empirical correction factors are introduced. In addition to the T-Sections large components, so called 'Double Corners', are tested in both in plane and out of plane direction to develop effective countermeasures for premature failure modes, such as throat washers and load distribution plates.
Ultra thick laminates for highly loaded main landing gear fittings
2008
15 Seiten, 16 Bilder, 8 Quellen
Aufsatz (Konferenz)
Englisch
Ultra Thick Laminates for Highly Loaded Main Landing Gear Fittings
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