In the preceding paper, we investigated theoretically the influences of filler shape, orientation distribution and interaction among fillers on the elastic reinforcement, assuming that the shape of filler was ellipsoidal.
In this paper, these theoretical results were examined experimentally, using model specimens. The specimens used were films or plates made of epoxy-resin and various fillers oriented uniaxially or at random.
The results obtained are as follows:
(1) As for the fibre reinforced epoxy-resin in which fibres are oriented uniaxially, the Young's modulus in the reinforcing direction is lower than that predicted theoretically. This is due to the facts that a small inclination of fibre axis from the reinforcing direction causes a substantial drop of Young's modulus, and that in practice the perfect orientation of fibres is difficult to be obtained.
(2) As for the specimens in which short glass fibres or flakes are filled at random, the orientation distribution of fillers is restricted by the thickness of specimen. And it seems that short fibres are oriented plane-randomly in the film specimens and space-randomly in the plate specimens. On the other hand, flakes seem to be oriented nearly uniaxially in the film specimens, but in the plate specimens the orientation of flakes seems to vary from space random to uniaxial as the dimension of flakes increases.
(3) When fillers are spherical, the 1st-order approximation of theoretical solution is useful for the range of lower than 10vol% of fillers, and the 2nd-order approximation is useful for the range of lower than 20vol%, with practical accuracy.
