Experimentation and modelling study of damping properties of multiwalled-CNT reinforced metal matrix composites

Abstract

The vibration energy that exists in most real structures is dissipated mainly because of the damping property of the material. This study investigates the effect of varying weight percentages of Multiwall Carbon Nanotubes (MWCNT) as reinforcement in Al, LM6, and LM25 composites fabricated through powder metallurgy on the damping behavior. Since the Aluminium (Al) and Aluminium- Silicon (Al-Si) alloys are the predominant materials in aerospace, automotive, and structural applications, the MWCNT reinforced Composite cylindrical ingots prepared through powder metallurgy method were hot-extruded to obtain rectangular strips and subjected to free vibration, impulse, and sweep sine tests to investigate the damping behavior. The 0.5 weight% (wt%) of MWCNT reinforced Al and Al-Si alloy nanocomposites exhibited marked improvement in mechanical and dynamic behavior. The Young’s modulus, and damping ratio decreased with further increases in wt% in MWCNT beyond 0.5. The increase in the damping ratio at 0.5 wt% MWCNT was observed to be 81.01%, 50.9%, and 38.1% whereas Young’s modulus improved by approximately 3.25%, 8%, and 7.4% for Al, LM6, and LM25 composites respectively compared to their base materials. Morphological analysis using transmission electron microscopy (TEM) revealed agglomeration of the reinforcement at higher percentages (above 0.5 wt%) and this supports the decrease in experimental values. The LM6 based composites exhibited the highest values of Young’s modulus, damping ratio and natural frequency followed by LM25 and Al-based composites at 0.5 wt%. The damping behavior of materials was modelled using the Rayleigh proportional damping model. The damping ratios obtained from the mathematical model and experiments were in close agreement. The prepared MWCNT-reinforced Al and Al-Si composites can be used in applications for vibration-sensitive engineering components, such as aircraft wings and fuselage support structures, automotive engine mounts, gearbox housings, brake components, machine tool structures, and precision rotating machinery, where high stiffness and improved vibration damping are essential. This work directly contributes to Sustainable Development Goals (SDG) 9, which includes advancement in composite materials, and SDG 12, which helps improve durability.