Optimal Fibre Orientation in Concrete-like Composites

OPTIMAL FIBRE ORIENTATION IN CONCRETE-LIKE COMPOSITES 

Institute of Fundamental Technological Research, Polish Academy of Sciences, Swietokrzyska 21, 00-0A9 Warsaw, Poland 

The paper deals with composite materials in which brittle matrix is reinforced with two systems of parallel continuous fibres. The stress and deformation states are determined for a composite element subjected to normal and tangent loads. The optimal directions of the systems of fibres are obtained from the criterion of the minimum of strain energy. The directional angle 9 of the first system of fibres and the angle a between 

Previous papers on the optimization of composite materials reinforced with fibres concern mostly the high strength composites [1],[2],[3]. Paper [4] deals with op timization of the internal structure of different kind of a material composed of brittle matrix and ductile fibres. In [A] the optimum fibre orientation is determined using maximum fracture energy as a criterion. The present paper concerns the optimization of a composite element in which brittle matrix is reinforced with ductile fibres, but at another optimization criterion the optimal directions of fibre systems are determined from the minimum strain energy of the element. 

The composite element is in shape of a plate of thickness 2h, in which the matrix is reinforced with two families of parallel fibres inclined at angles O and 0 +a to axis x - Fig.l. 

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