Effect of low frequency vibrations on void content in composite materials

Eliminating common defects such as voids, bubbles, and poor adhesion at interfaces will increase the quality of laminated sandwich composite structure. This work reports experimental research and analysis of the effect of mechanical vibrations applied to the curing system of composite materials production, particularly for minimizing void content. Range of frequency of vibrations covered was from 10 to 50 Hz, for different period of vibrations. The composite laminates were made by hand lay-up using glass fibers and vinyl-ester resin, and examined under microscope to determine types and quantity of defects. The results showed reduction in void content when vibrations were applied for 30 min.