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In this article, the physical and Geometrical effective parameters on free vibration and Force impact a three-layer sandwich plate in the middle layer with magneto rheological (core) Under cross-shot with low speed is investigated. The first natural frequency and loss factor of comparable modal for the first four vibrative modes for Core thickness, magnetic fields and different sheet’s geometrical parameters, is founded. The MR material shows variations in the rheological properties when subjected to varying magnetic fields. These materials with fast response time (in milliseconds) Through a detailed with variation in Magnetic field can be controlled. The governing equations of motion were obtained using Hamilton̕s principle. The results were obtained by the systematic analytical solution. Using the two degrees of freedom mass-spring model, the contact force function can be obtained analytically. The obtained natural frequency from eigen value problem, was used for calculating of equivalent mass of the plate in spring mass model. The results show that with systematic variation of magnetic field and with increasing the ratio of core thickness to the layer thickness and also with increasing the ratio of length to the whole of sheet thickness, we can in order, the stiffness, structural loss factor coefficient and maximum contact force can be changed and controlled.

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In this study, using design of experiments, the effect of hybrid graphenenanosheets and nano clay and compatibilizer maleic anhydride -grafted -polypropylene (PP-g-MA) on the impact strength polypropylene-based nanocomposites were investigated. Design of experiments and analysis of experimental data with Minitab 16 software and response surface methodology were carried out. Making nanocomposites, based on the melt mixing was performed. Statistical models provided by response surface methodology good agreement with experimental results and with respect to the values of R-sq and R-sq (adj) have a good reputation. Statistical analysis showed that increasing the percentage of nanoparticles, impact strength decreases. Compounds morphology by Scanning Electron Microscopy (SEM) was performed. Micrographes showed better dispersion of the particles in lower percentages. Thermal analysis using differential scanning calorimetry (DSC) showed that the presence of graphene have little effect on the melting temperature of the sample being tested, but Tc of nanocomposites compared with pure PP, has increased about 4 percent. Also Thecrystallinity was reduced by adding graphene. In the non-graphenenanocomposites, the clay did not affect the melting temperature,but the crystallinityand crystallization temperature increased 10.73 % and 2.23 % respectively compared with pure PP that showed nucleation effect of nano clay.

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Free vibration characteristics of rectangular composite plate with constrained layer damping and magneto-rheological fluid (MR) core are presented.. Hamilton principal is used to obtain the equation of motion of the sandwich plate. Based on the Navier method, a closed-form solution is presented for free vibration analysis of MR sandwich plate under simply supported boundary conditions. The governing equation of motion is derived on the base of classical lamination theory for the faceplates. Only shear strain energy density of the core is considered. Using displacement continuity conditions at the interface of the layers and core, shear strain of the core is expressed in terms of displacement components of the base and constraint layers. The complex shear modulus of the MR material in the pre-yield region was described by complex modulus approach as a function of magnetic field intensity. The validity of the developed formulation is demonstrated by comparing the results in terms of natural frequencies with those in the available literature. The effects of magnetic field intensity, plate aspect ratio, thicknesses of the MR core, base layer and constrained layer for three different stacking sequences of composite faceplates on the fundamental frequency and loss factor of the first mode are discussed. The results indicate significant effect of physical and geometrical parameters on the natural frequency and loss factor associated with the first mode.

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Manufacturing in as short time as possible, with highest quality and at minimal cost, is one of the key factors in industry. As a result, researchers are seeking new methods and technologies to meet such requirements. Liquid impact forming is one of such methods which has received wide currency especially in automotive and aerospace industries. In this method, which is considered as one of tubular hydroforming processes, forming is achieved by using liquid pressure. In this paper, liquid impact forming process was investigated experimentally and numerically for a thin-walled aluminium tube. In experimental part, a die was designed and manufactured to transform the cross section of the aluminium tube into a polygon which at the end of the process changes the cylindrical shape of the tube to a profile almost similar to a trapezoid. Results showed that a die in the form of matrix molding is not suitable for this type of geometry in such a process while using another die which consisted of three parts resulted in a satisfactory forming. Simulation of this process was further implemented using finite element method and results relating to Von Mises stress distribution, displacement, strain energy, internal energy, thickness variation and the force required to implement the process were obtained. Displacement distribution in different regions indicated that no wrinkling occurred in the sample. Comparison between simulation and experimental results indicated that they were in good agreement.

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One of the common ways to reduce vibration in the structures is to add a thin viscoelastic material layer to the structure. By appropriate using of viscoelastic materials one may increase modal loss factor of the structure and reduce unfavorable structural vibration which is a main cause of fatigue and failure in the structures. In this paper, low velocity impact response of sandwich plate with magnetorheological fluid core is investigated. Hamilton principal is used to obtain the governing equation of motion for sandwich plate. Free vibration problem of the sandwich plate is solved using the Navier solution method. Classical lamination theory is used to analyze the mechanical behavior of the composite laminate in the facesheets. Only shear strain energy of the core is considered and viscoelastic behavior of the MR material was described by complex shear modulus approach as a function of magnetic field intensity. Furthermore, analytical solution for impact force is obtained by a two degree of freedom spring mass model. For three different stacking sequence of face layers, contact for history and variation of maximum impact force and it’s corresponding time by magnetic field intensity is investigated. The results show considerable effect of variation in magnetic field intensity on maximum impact force and it’s corresponding time.

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In this study, free vibrations and resonances analysis of a nanocomposite beam with internal damping is investigated. For this purpose the various distributions of carbon nanotubes with arbitrary average volume fractions are considered. System includes the geometry and inertia nonlinearities. With the aid of Hamilton principle the equations of motion are derived and using the Galerkin method are reduced to ordinary ones. To analyze the system the multiple scales method is utilized. In free analysis the analytical expressions for amplitude, phase and nonlinear natural frequency are obtained. Also, the effect of system parameters such as damping coefficients, kind of the carbon nanotube distribution, average volume fraction of nanotubes in them are probed. In free analysis, it is observed that by increasing the external damping the amplitude is decreased. Also, by increasing the average volume fraction, the nonlinear natural frequency is increased. In resonance analysis, by depicting the frequency response curves, it is observed that by increasing internal damping coefficient the amplitude is decreased and the loci of the bifurcations is changed. Also carbon nanotube distribution and average volume fractions of them on the solution and bifurcations have an important effect. Also, it is seen that by decreasing the external force, the amplitude of the system is decreased and bifurcations occur in higher internal damping coefficients. An isotropic beam in the highest and a nano-composite beam in the lowest values of internal damping coefficients become completely stable.

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Powder metallurgy process is commonly used to manufacture nanocomposite products, in which the product quality of this process depends upon Composite of reinforcement nanoparticle and distribution. In this article Metal Matrix Nanocomposite (MMN) by powder metallurgy with a base material stainless steel 316L, a material that is widely used in the industry, and reinforcement particles mixture of Carbide Titanium (TiC) as carbon-based reinforcing particles, and Hexagonal Nitride Boron (hBN) particles as the self-lubricating material is prepared. The reinforcement powders were micro Sized and mixed in high ball milling to reach Nano-sized, after 30 h mixing powders in high ball milling reach to Nano-sized, and then reinforcement Nanoparticles with 2 and 10 Wt.% Mixed with stainless steel 316L for 5 hours and compacted at 400 Mpa and sintered at 1400 C temperature and 3 Hours. Scanning electron microscope (SEM), Energy-dispersive X-ray Spectroscopy (EDX) and X-ray Diffraction (XRD) tests are performed on Powders to identify the nanocomposite microstructure. The Mechanical Properties such as Microhardness, Wear, and Bending Strength Were Analyzed. These results Compare with Results of stainless steel 316L without Reinforcement. Microhardness and abrasion resistance of Nanocomposite material have improved and flexural strength improved at the sample with 2 wt.% reinforcement and reduced at the sample with 10 Wt.%.

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In this paper free and forced vibrations analysis of a viscoelastic nonlinear nano rotating beam by considering surface effects is investigated. Using Hamilton principle and Gurtin Murdoch theory, the equations of motion are obtained and discretized by Galerkin method. Using the multiple time scales method the equations of motion are solved. In free vibrations analysis, the analytical expressions for amplitude and phase are obtained. In forced vibrations analysis the steady state solution are obtained. The effect of surface effect, damping coefficients, dimensions of cross section area, external excitation amplitude etc. on frequency response curves are investigated. It is seen that in free vibrations, by increasing surface stress the amplitude of the system decreased, and by increasing surface density or elasticity it is increased. Also, by increasing internal and external damping coefficients free vibration amplitude is decreased. In forced vibrations, it is seen that considering surface effect the amplitude of the system is decreased and the first bifurcation point is obviously changed. By increasing internal and external damping coefficients the amplitude is decreased and the first bifurcation point occur in frequencies near the natural frequency. It is seen that for two different dimensions of cross section with same area, amplitude and the loci of the bifurcation points are changed. By increasing the amplitude of external excitation the amplitude of response is increased the bifurcation points occur in frequencies far away from natural frequency. So, considering the surface effects for free and forced vibrations analysis of the nano rotating beams is mandatory.