The effect of carbon nanotubes modified polyurethane adhesive on the impact behavior of sandwich structures

Abstract

AbstractSandwich panels with aluminum honeycomb cores have emerged as an essential class of lightweight building materials in a wide variety of structural engineering areas, including marine, railway, aerospace, and automotive structures. Although sandwich structures offer remarkable mechanical properties, for instance, high specific strength and stiffness, these structures are open to the damage created by the low‐velocity impact. This study investigates the dynamic behavior of aluminum honeycomb sandwich panels with different core cell sizes based on neat and multi‐walled carbon nanotube (MWCNT) reinforced polyurethane (PU) adhesives that are aimed. The enhancement in impact performance of honeycomb sandwich structures obtained by the inclusion of MWCNTs in the PU adhesive is investigated. The effect of the MWCNT reinforcements on square sandwich panels at 50 J energy level is examined using an instrumented drop tower test setup. After acquiring load–time histories, the numerical integration method is implemented to obtain load–deflection and energy–time curves. Also, energy balance modeling (EBM) is utilized to characterize the effectualness of MWCNT reinforcement to PU adhesive on the impact behavior of sandwich panels. Theoretical EBM is confirmed that absorbed energy in the shear and bending deflections increased as the percentage of MWCNT‐added PU adhesive increases. Understanding the damage event implicated in absorbing and dissipating the impact energy is determined and compared for panels with different cell sizes, including nanoparticles, using the macroscopic optical images and microscopic scanning electron microscopy images of sandwich panels.