This paper studies free vibration of simply supported functionally graded beams with piezoelectric layers subjected to axial compressive loads. The Young's modulus of beam is assumed to be graded continuously across the beam thickness. Applying the Hamilton’s principle, the governing equation is established. Resulting equation is solved using the Euler’s Equation. The effects of the constituent volume fractions, the influences of applied voltage and axial compressive loads on the vibration frequency are presented. To investigate the accuracy of the present analysis, a compression study is carried out with a known data. پرونده مقاله

This paper presents the preparation and mechanical properties of compatibilized compositionally graded Polyethylene/ low density polyethylene (LDPE)/ modified montmorillonite (MMT) nanocomposites prepared by solution and melt mixing techniques. Use of polyethylene glycol as compatibilizer improves compatibility of modified montmorillonite and low density polyethylene. Comparisons between two techniques show that the melt mixing technique is the preferred method for preparation the Polyethylene/Clay nanocomposites for uniform and compositionally graded distributions. It is observed, the addition of Nano clay improves the mechanical properties like tensile strength. Also, it is noticed the mechanical properties of compositionally graded Polyethylene/Clay nanocomposites are improved rather than the uniform distribution of Polyethylene/Clay nanocomposites. The morphology of nanocomposites cross section samples is studied by Scanning Electron Microscopy (SEM) and finally the comparison are made between two techniques and then between compositionally graded polyethylene/clay nanocomposites with uniform ones. Its show that when the compatibilizer was added for melt mixing technique, the density and the size of the aggregates decreased, which indicates that the dispersion of nano clays within the polymer matrix is much better. پرونده مقاله

This paper studies dynamic stability of functionally graded beams with piezoelectric layers subjected to periodic axial compressive load that is simply supported at both ends lies on a continuous elastic foundation. The Young’s modulus of beam is assumed to be graded continuously across the beam thickness. Applying the Hamilton’s principle, the governing dynamic equation is established. The effects of the constituent volume fractions, the influences of applied voltage, foundation coefficient and piezoelectric thickness on the unstable regions are presented. پرونده مقاله

In this paper, the causes of the crack initiation in cast iron bullion moulds in Meybod Steel Corporation are investigated and then some new geometrical models are presented to replace the current moulds. Finally, among the new presented models and according to the life assessment, the best model is selected and suggested as the replaced one. For this purpose, the three recommended moulds were modeled and analyzed by ANSYS software. First, a thermal analysis and then a thermo-mechanical coupled field analysis were performed on each three model. The results of the analysis are used to determine the critical zone. The critical zone is selected on the symmetric axis of the inner surface of the mould. By comparing the principle stress contours and temperature distribution contours of three models, one of the suggested models was selected as optimized geometrical model. Then, the crack modeling and the life assessment on the optimized model were implemented and the total life of the model was calculated. Comparison of the life of the optimized and the initial models shows an increase in the life of the suggested model. The results are verified with the experiments. پرونده مقاله