THE MEASUREMENT OF THE 3 PRINCIPAL ELASTIC-MODULI OF UNIDIRECTIONAL COMPOSITES

A filament winding technique for the manufacture of unidirectional fiber reinforced composites with highly reproducible properties is described. Since the intrinsic vibration frequency of an elastic bar is dependent on the elastic modulus of the bar material, the elastic modulus may be calculated from the resonant frequency measured by an acoustic vibration test. A simple sonic method has been used to measure the elastic moduli along the three principal directions in certain unidirectional composites. The results obtained are discussed.