Paper number 256

FATIGUE OF 3D SANDWICH-FABRIC COMPOSITES UNDER CORE SHEAR LOADING

Hermawan Judawisastra, Jan Ivens, Ignaas Verpoest

Department of Metallurgy and Materials Engineering, Katholieke Universiteit Leuven,
De Croylaan 2, B-3001 Leuven, Belgium

Summary The core shear fatigue behaviour of 3D sandwich-fabric composites has been investigated. Four types of glass fibre-epoxy sandwich panels with different core properties were used in this research. A three point bending fatigue test set-up was used. The use of one millimetres thick metal plates as extra skins on the panels generates mainly shear loading in the sandwich core. Fatigue tests were performed at different load levels, based on the static 3PB strength. During the test, the load was kept constant and the bending displacement was monitored to obtain data on the properties degradation. Based on the stiffness degradation curves, a fatigue design criterion for sandwich-fabric panels is proposed. Damage growth was monitored by means of stereo light-microscopy and X-ray radiography (upgraded to a Tomohawk Computer Tomography System) techniques. Comparison of the stiffness degradation curves showed that it is strongly influenced by the core microstructure. Damage investigation revealed the material phenomena, responsible for this degradation.
Keywords sandwich structures, fatigue, damage, textile composites, NDE technique.

Theme : Composite Structures ; Sandwiches

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