Experimental and virtual testing of a composite-aluminium aircraft wingbox under thermal loading

Abstract

Nowadays, carbon fibre composites are increasingly being used in aircraft which, in turn, has lead to carbon-metallic bolted assemblies. The large difference in the thermal expansion coefficient between these materials, and the considerable temperature excursions that occur during aircraft operations, lead to thermal stresses that may trigger different forms of local damage. This complex phenomenon can affect the integrity of large primary structural components such as an aircraft wingbox. In this work, we perform an experimental campaign and a finite element simulation of a full hybrid carbon-aluminium wingbox assembly. The structure contains two rib designs: a baseline rib and a new stiffer rib design with the objective of improving the structural behaviour. The wingbox was subjected to thermal loading. The numerical model is validated against the experimental data and employed to study additional phenomena in detail that cannot be analysed directly from the experiments. The model is able to reproduce reasonably well the experimental data, and demonstrates that thermal loading cannot be neglected since it leads to considerable stresses, particularly in the metallic ribs. Moreover, the stiffer rib design provides improved behaviour mainly at the bolted joints with the spar.