Comparative study of transverse vibration and mechanical properties of aluminium, Al 7020 alloy, and MWCNTs reinforced aluminium nanocomposites

Alloys that mostly composed of aluminium are widely used in structural engineering especially in the aircraft industry. However, cyclic vibration may generate microcracks which lead to failure. Mechanical vibration is one of the most popular issues in any working machine. Besides, the vibration energy may transfer to the other portion of the structure as any mechanical waves causing noises, loose parts, heat, and wear. Structure damping and vibration isolation are the main two solutions to solve this problem. Metals behave like viscoelastic materials that made them a candidate to serve as dampers. Therefore, this paper investigates the transverse vibration and mechanical properties of aluminium, Al7020 alloy (Al-Zn-Mg alloy) and aluminum-multi-walled carbon nanotubes (Al-MWCNTs) nanocomposites. The samples were prepared using an open mould casting approach with flex. Experimental comparative study of dynamic behaviour and mechanical characteristics for the prepared samples were investigated. Transverse vibration test at different frequencies (motor rotating speed 0-3000 rpm) with and without loading, tensile test, flexural bending, and Vickers hardness tests were determined. Surface morphology and chemical analysis of as a cast prepared samples were characterized utilizing scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS) and optical microscope. The obtained results revealed different dynamic behaviour and mechanical properties of prepared samples due to the different microstructure effect generating from the addition of materials (alloying element and reinforcing materials). Al7020 alloy showed the highest ultimate tensile strength, axial stiffness, flexural strength, bending modulus, fracture toughness, and hardness compared with the other samples. Al-MWCNTs nanocomposites revealed minimum ultimate tensile strength, axial stiffness, and elongation % at the break, bending modulus, fracture toughness and maximum deflection. Moreover, the dynamic behaviour of all samples is dissimilar under transverse vibration test when applied load and frequency were changed. The Al-MWCNTs nanocomposites exhibited the most stable structure under transverse vibration test at maximum applied load and higher frequencies