Manufacturing of damping composite laminates with aeronautical prepreg and elastomeric interlayer

Damping composite laminates have been produced by compression molding of commercial thermosetting carbon fiber reinforced prepregs with different interlayers. A double-stage experimental campaign was implemented to select optimal candidates for these interlayers to improve laminate damping. In the first stage, dynamic mechanical analysis (DMA) was carried out on inert, thermoplastic and thermosetting materials. Measured loss factors ranged between 0.06 and 0.34. DMA and bending tests were also carried out on small size laminates by using those interlayers as core of composite sandwiches. After incorporation in the sandwich structures, loss factor values reduced down to 60%, but the improvement in comparison with the neat laminate was always remarkable (from 16 to 19 times). By combining damping and mechanical performances of composites with optimal manufacturability, only the rubber interlayers were selected for the second experimental stage when five samples were manufactured with bigger size, and tested under bending and dynamic loading. Because of the rubber interlayer, the apparent bending modulus of the damping samples strongly decreased, down to 11 times, whereas the stiffness remained about 50% of the neat laminate on average. Nevertheless, results from damping of free bending vibrations show that these laminates reduce, on average, about 50% of their maximum acceleration.