炭素繊維の繊維軸方向音波弾性率

概要

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For a series of polyacrylonitrile (PAN) -based carbon fibers, measurements of sonic modulus in fiber-axis direction have been carried out on tows and on carbon fiber-epoxy resin composite strands. It has been obtained that the sonic modulus of composite strands, Es, c, can be represented by a rule of mixture, Es, c=Es, f υf +Es, m(1-υf), where Es, f and Es, m are sonic moduli of fiber and matrix, and Uf is fiber fractional volume. From this, it results that the measurement of sonic modulus of composite strands can be applied as a convenient method for determining the fractional volume of fiber in composite strands if the sonic moduli of fiber and matrix are known in advance. The variation of sonic modulus of carbon fibers with applied stress has been also investigated. The relation between the modulus Ef of carbon fibers and the applied stress c at small stresses can be represented as Ef=[1-(2S111/S11)σ]/S11 where S11 is the initial compliance. The factor 2S111/S11 has shown almost a constant value for a variety of PAN-based carbon fibers. The relations between the parameters representing the dependence of the sonic modulus on the applied stress and the fiber-structural parameters are shown.
日本複合材料学会の論文