الفهرس 
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Abstract
In the present work, aluminum metal matrix reinforced with (Al2O3) nanoparticles has been successfully fabricated using friction stir processing (FSP). Effect of processing parameters such as tool rotation speed, travel speed and number of passes on the mechanical and dynamic behavior are investigated. The dynamic properties are tested using free vibration analysis in order to measure the natural frequency response (fn), and damping capacity (ξ), loss factor η, storage modulus (E’), loss modulus (E”) and shear modulus (G). The results revealed that, Multi-Pass FSP causes a homogeneous distribution and good dispersion of Al2O3 in the metal matrix
and consequently an increasing in the hardness of the matrix composites. Finer grain is observed from the microstructure examination in the second and third passes FSPed specimens, the improvement in the grain refinement is 80% with respect to base metal. The processing parameters, particularly rotation speed and number of passes in FSP have a significant influence on the mechanical properties. The Mechanical properties, such as ultimate tensile strength (UTS) and hardness are improved by 25 % and 46% respectively due to increasing passes number and the presence of reinforcement Al2O3 nanoparticles. Regard to the dynamic characteristics, the damping capacity has been enhanced as increasing the number of passes.
Simulation model has been carried out using commercial finite element analysis software ANSYS, in order to verify the theoretical calculation with practical measurements for dynamic properties. The emulated Natural frequency and mode shapes were very close by 2.75 % error with respect to the measured values.