Abstract: In the present paper, the effect of the rotation and non-homogeneous on the wave propagation in orthotropic material is discussed on the basis of the linear theory of elasticity. The one-dimensional equation of elastodynamic is solved in terms of radial displacement. Three different boundary are considered, namely the free, fixed and mixed orthotropic material. The determination is concerned with the eigenvalues of the natural frequency of the radial vibrations for different boundary conditions in the case of harmonic vibrations. Numerical results are given and illustrated graphically for each case considered. Comparisons are made with the results in the absence of rotation and non-homogeneity.

Abstract: This paper discusses the effect of casting processing parameter on the mechanical properties of Aluminum alloy 6061 companied with Al2O3 and Si CP. The specimens were poured in two different mold types one of steel and the other of graphite. These two types have a wide range of cooling rate; steel has fast cooling rate whereas graphite has slow one. In order to investigate this effect, and the alloying elements participation the specimens were taken from three different positions in the mold; top, middle and bottom. The mechanical wear, hardness and microstructure examination were performed. The results showed that wear rate and hardness increase in case of specimen poured in steel mold.  This increasing due to fast cooling rate which make refining of the grain size of aluminum alloys. Whereas, their mechanical properties decreased when using graphite molds. In contrast of this result, ductility is increased. This is attributed to that graphite has slow cooling rate (heat dissipate is low) which make enlargement to the grain size of aluminum alloy and the graphite is also solid lubricate playing as interactive lubricate which is main reason to decrease the wear rate.