Design of lightweight damping core for composite sandwich structure

Abstract The damping performance and lightweight design requirements of composite sandwich structure core were studied. A series of low density damping cores were prepared by blending epoxy/polyurethane graft copolymer (E‐g‐U) and epoxy/poly mercaptan block copolymer (E‐b‐M) with different contents of hollow glass beads (HGM). The damping properties, mechanical properties, density, and interface morphology of the core layer were studied. The damping response and flexure properties of the sandwich composite structure were studied by modal analysis and three‐point flexure test. The experimental results show that optimal damping performance of matrix appears at 60% E‐b‐M ratio, the peak loss factor is 0.88, and the damping temperature range covers −2 ~ 52°C. When the HGM content in the core is 10 phr, the density can be comparable to that of the buoyancy material. Under flexural load, the ultimate shear strength and shear modulus of the sandwich structure increase maximum at 15 phr and 10 phr, respectively. Compared with the unfilled HGM sample, the first three modal damping ratios of the sandwich structure are increased by 133.2%, 56.6%, and 56% by 10 phr damping core, respectively. The results are compared with those in other reference. The research shows that the design of lightweight damping core is expected to provide a core material selection for the vibration reduction of sandwich structures.