Determination of elastic constants of glass/epoxy unidirectional laminates by the vibration testing of plates

Identification of elastic properties of unidirectional glass/epoxy laminates from the measured eigenfrequencies has been performed. The stiffness of the laminates has been investigated by a mixed numerical/experimental method employing the vibration test of plates. Elastic constants of laminates have been determined by using an identification procedure based on experiment design, the finite-element method and the response-surface approach. Elastic properties of laminates with two different fibre-surface treatments have been compared. It was found that only for the transverse elastic modulus is there a statistically significant difference between the composites with good and poor fibre/matrix adhesion.