Indirect Determination of Mechanical Properties of Reinforcement in Fibrous Polymeric Composites

Abstract

Mechanical properties of reinforcing fibres, embedded in a polymer matrix, are at least to some extent unknown quantities and still under investigation. Their values, found mostly in manufacturer’s catalogues, seem in many cases to be doubtful, especially regarding such properties as transverse modulus of elasticity or Poisson’s ratios. Moreover, in some cases an assumption of isotropy of the fibres, even in the case of glass-fibres, may be unfounded. The present paper presents a method of calculation of the values of the fibre’s elasticity constants, based on global elastic constants of the composite. Numerical simulation proves, that all five constants of monotropy, eventually expected in reinforcing fibres, can be evaluated with errors below 5%.