An investigation into methods to enhance the interlaminar shear strength of continuous fibre reinforced ceramics

This Master Thesis investigates the possibility to implement new innovative textile techniques for the manufacturing of fibre reinforced ceramics with the purpose of enhancing the interlaminar properties. A needling technique is developed that pushes fibre material into and through a laminate, creating a 3-dimensional structure. This results in a stable structure that is suitable as a preform onto which a non-oxide ceramic matrix such as graphite or silicon carbide can be placed using a vapour deposition or vapour infiltration process. By manufacturing specimens made of unidirectional carbon fabrics and an epoxy matrix, the crack initiation and propagation during destructive testing is analysed. The study shows that the failure mechanism for such a needled material is changed during bending loads. This is due to the modification of the fibre structure that creates through the thickness fibres. It is demonstrated that it is possible to increase the energy absorption and the fracture toughness of the needled material. In addition, an electrostatic flocking procedure for creating interlaminar fibres is investigated using electromagnetic field theory combined with numerical analysis. Via theory and conventional techniques a manufacturing procedure for flocked material is developed and shown to display great potential for increasing interlaminar shear strength of any laminated fibre-reinforced material. Finally, the possibility to implement the above techniques into industry and the methods to do so is demonstrated.Validerat; 20101217 (root