Merged with duplicate record 10026.1/2475 on 15.03.2017 by CS (TIS)Fibre composite hybrid materials are generally plastics reinforced with two different
fibre species. The combination of these three materials (in this thesis they are carbon
fibres, glass fibres and polyester resin) allows a balance to be achieved between the properties
of the two monofibre composites. Over the fifteen years since the introduction of
continuous carbon fibre as a reinforcement, there has been considerable speculation
about the "hybrid effect", a synergistic strengthening of reinforced plastics with two
fibres when compared with the strength predicted from a weighted average from the component
composites.
A new equation is presented which predicts the extent of the hybrid effect. Experiments
with a variety of carbon-glass hybrids were undertaken to examine the validity of
the theory and the effect of the degree of inter-mixing of the fibres. The classification
and quantification of the hybrid microstructures was examined with a view to crosscorrelation
of the intimacy of mixing and the strength.
Mechanical tests were monitored with acoustic emission counting and acoustic emission
amplitude distribution equipment. Some specimens were subjected to one thermal cycle
to liquid nitrogen temperature prior to testing. Fracture surfaces were examined in the
scanning electron microscope.
Numerical analysis by finite element methods was attempted. A constant strain triangular
element was used initially, but in the later analyses the PAFEC anisotropic
isoparametric quadrilateral elements were used. The system was adapted so that a \Ir
singularity could be modelled, and post processor software was written to allow nodal
averaging of the stresses and the presentation of this data graphically as stress contour
maps
