Experimental investigation of the geometric structural parameters of honeycomb cores with regard to their influence on resin distribution and compressive strength
Bachelor / Master thesis / Research thesis
Motivation
In aircraft, a large number of structural components are constructed using sandwich construction. Due to the combination of stiff outer layers and lightweight honeycomb core structures, these components exhibit very high mechanical properties relative to their weight. The primary function of the honeycomb cores is to absorb transverse forces, and they are therefore subjected to compressive and shear stresses. Typical honeycomb cores are manufactured using an expansion process. In this process, thin aramid papers are partially coated with adhesive, stacked, and pressed. The honeycomb cells formed by the expansion of the paper block are then immersed in a resin bath. This process adjusts the mechanical properties and improves the fire behavior.
During the coating of the expanded paper honeycombs, resin accumulations form in the corners of the cells, which significantly determine the mechanical properties of the core.
The design of sandwich structures is based, among other things, on knowledge of the precise load-bearing behavior of the core structures. The aim of this thesis is therefore to investigate the influence of the structural parameters of honeycomb cores on the formation of local resin concentrations and their effect on the mechanical properties of the core.
Key Focus Areas:
- Literature review on honeycomb cores, core materials used, manufacturing processes for classic aramid paper honeycombs, and compression tests on sandwich cores
- Analysis of suitable sample preparation methods for investigating the impregnation process
- Design and development of a device for the manual production of sandwich core sections
- Production of sandwich core samples with varying parameters regarding cell width, paper type, and expansion angle using the developed apparatus
- Experimental design and execution of the impregnation process of the samples with epoxy resin
- Analysis and evaluation of the impregnated samples regarding the formation of resin corners and cell wall areas with increased resin concentrations using suitable methods
- Conducting compression tests on the manufactured sandwich core samples
- Critical discussion of the results
© Sven Ellger
Research Associate
NameMr Dipl.-Ing. Dominik Brunner
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Chair of Aircraft Engineering
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