| Abstract: | Model Investigation of the Fibre Reinforcement of Ceramic Materials A mechanism for fibre reinforcement of high-modulus brittle materials, in particular ceramics, is investigated both experimentally and theoretically. A simple mathematical formalism representing crack extension in a brittle matrix reinforced by ductile fibres is derived, and characteristic property values, adapted to composite structures, are introduced. Alumina with unidirectional reinforcement by thin 80Ni20Cr wires is used as a model material. The mechanism presented allows to reduce the high sensivity of ceramic materials to cracks. It is necessary for the fibres to bridge matrix cracks under load. For this purpose, the fibres must not be bound too tightly to the matrix, and while a high ductility is certainly of value, it is not a necessity. The efficiency of the mechanism depends on - – interface energy and friction at the matrix-fibre interface,
- – deformation and fracture behavior of the fibre material,
- – radius of the fibres,
- – volume fraction of the fibres,
- – critical stress intensity factor of the matrix,
- – size of the largest crack.
Among these, the fibre radius appears to be the most suitable one for variation with the goal of optimizing material quality. |
