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Characterization of Composite Materials

BFK_SHTB

 above: A composite made from Basalt fibres and an epoxy matrix is subjected to dynamic loading using our Split-Hopkinson Tension Bar.

 

Our research interests include the mechanical behavior of fibre-reinforced materials. Among these, we consider Biocomposites, containing natural fibres, e.g. flax, hemp or kenaf. We also study mineral Basalt fibres as reinforcing materials, which are promising alternatives to glass and carbon fibres in terms of mechanical properties and environmental impact.

 

Fig. 1: Example of Hemp fibre reinforcement and a tensile specimen made from this fibre reinforcement and an epoxy resin based on natural vegetable oil.

 

The material behavior is investigated in our Materials Characterization Lab.
Our equipment includes:

  • 100 kN Universal testing machine made by Zwick for tension, compression, shear and bending experiments
  • Climate chamber for experiments at different temperatures
  • Split-Hopkinson Bars for dynamic experiments in both tension and compression
  • State-of-the art Digital Image Correlation (DIC) methods for accurately determining stresses in a contactless way using high-resolution cameras

An example the data gathered in our lab is given below. A basalt-fibre/epoxy composite with unidirectional fibre orientation is loaded in tension, while the strain is determined using DIC. The resulting stress-strain curve allows the identification of the Young’s modulus and the failure strength.

 Fig. 2: Examplary stress/strain curve for a unidirectional basalt fibre-reinforced composite loaded along the fibre direction in tension. The bottom part shows the specimen before and after failure.