The ensuing analysis is carried out with reference to epoxy resin/glass sphere filler reinforced composites with constituent properties of, Em, Ep, nm, and np of 3.6 GPa, 76 GPa, 0.4 and 0.23, respectively in order to assess the effectiveness of the modified expressions in predicting the properties of composites. In doing so, the standard practice used in the study of composite materials, of developing curves of composite property against reinforcement volume fraction is adopted, where the latter is varied from a value of zero for the pure matrix to 100% for the pure reinforcement. It is understood that the packing geometry does limit the reinforcement volume fraction to, for instance in the case of rectangular and hexagonal packed fibres, theoretical limiting values of 78.6% and 90.7%, respectively. The commercial limits of reinforcement are however must lower than these limiting values and are depended on both the moulding process and form of reinforcement. Values of 40%, 60%, 60%, 65% and 70% apply for hand layup, vacuum bag, infusion, pre-preg and autoclave methods, respectively. Values of 70-72% for unidirectional fibres, 0.60 – 0.65% for stitched non-crimp fibres 0.40 – 0.55% for woven fabric and 0.15 – 0.25% random chopped strand mat. A theoretical limit for rigid mono-sized particles of 74% has been determined, with observed practical limits lying between 60 – 64%.
Author(s) Details:
Maina Maringa,
Department of Mechanical and Mechatronic Engineering, Central University of Technology, Private Bag X20539, 20 President Brand Street Westdene, Bloemfontein, 9300, Free State, South Africa.