JOURNAL OF SIMULATION AND ANALYSIS OF NOVEL TECHNOLOGIES IN MECHANICAL ENGINEERING (JOURNAL OF SOLID MECHANICS IN ENGINEERING)
Year:2015 | Volume:7 | Issue:3 (17)|Papers Count:8

In this paper, free vibration analysis of a polymer-based nano-composite beam reinforced by boron-nitride nanotubes and subjected on elastic foundation, is studied. Smooth and defect-free nanotubes with uniform and directly- orientated in matrix are intended. Also, nanotubes’ distribution in the thickness direction of beam is regarded as a uniform distribution of the three different targeted ones. The properties of nano-beam are obtained by using a micromechanical model. The governing equations based on Timoshenko beam theory are derived by using the Hamilton principle. The equations are solved by the extended differential Quadrature and the natural frequencies are obtained. The effect of various parameters such as volume fraction of nanotubes, carbon-nanotube (CNT) distribution in the thickness direction of the beam, elastic media, boundary conditions and the aspect ratio is investigated on the natural frequency. The results show that a change on these parameters has a significant impact on the natural frequency.

Surface finishing is one of the most significant steps in industries which are engaged with surface quality. Finishing by magnetic field is a new method of surface finishing. In this process, machining is executed in mechanical way and semi-homogeneous abrasive slurry performs finishing of surfaces. Needed force to grind surfaces is made by magnetic field. Therefor this method is considered as an advanced machining method. One of application of advanced machining methods is working in situation which conventional methods are not applicable. Nowadays helical and spiral parts have an important position in industry. This result in more attention about manufacturing and finishing of parts. This mechanism is used to finish helical ball screw in CNC machine using magnetic field created by Nd-Fe-B permanent magnet. In executed experiments four parameters which affected on surface quality were investigated. These parameters included feed rate, particles size and amount of ferromagnetic particles. The effect of most parameters was positive and caused to improve surface quality, but generally each parameter had an optimum amount in which by reaching this amount, reducing in efficiency and surface quality was observed. Also, some parameters such as cutting speed had lower effect. The initial specimen had surface roughness of 1.017 µm and the best resultant surface quality was 0.325 µm.

In this study, the natural frequencies and mode shapes of beams without cracks and cracked Timoshenko beams is calculated with different boundary conditions using finite element method. The energy method is used to solve the equations. Hardness and softness matrices for Timoshenko beam without crack are obtained by solving the potential and kinetic energy equations. Then for investigation of cracked condition, the cracked element stiffness matrix is used and the beam natural frequencies are obtained by entering the boundary conditions of the beam. After that the effect of bed is investigated by addition of it to the equations.

Buckling analysis of thin cylindrical shells is very important due to their production process.  Usually longitudinal and transversal stiffeners are used to increase the buckling stiffness. In this paper, considering a thin cylindrical shell with longitudinal and transversal ribs subjected to axial force and lateral pressure, the influence of different aspect of axial force to lateral pressure on buckling load is investigated for different ratios such as thickness to radius and length to radius. The analytical results based on Donnell’s classical linear stability equations for anisotropic cylindrical shells are compared with FEM results of ANSYS software. The results show that the analytical method of Donnell can be used for special aspect ratios. Furthermore, by increasing the axial to lateral load ratio, the axial buckling load is increased for most of the aspect ratios, while the lateral buckling load decreases.

In this paper the influence of different parameters on equal channel angular pressing (EADAP) of titanium alloy is investigated. In the first step the most important parameters are selected, and then a table of experiments is designed using Taguchi method. After designing the table of experiments, all of the experiments are simulated using Abacus software and the results are optimized using Taguchi method. The results shows that the optimum levels for ECAP method between the implemented experiments of titanium are 120 degrees for die channel, ambient temperature and 2 passes.

Due to the importance of power generation cycles including combined cycle, many studies have been done in recent years and many researchers have been tried to optimize these cycles by using of existing methods. In this study, the Water-Ammonia cycle is investigated in the combined-cycle of the Water-Ammonia, working dual Water-Ammonia mixture is used as the works fluid. This cycle can be used from different sources such as typical power dissipation of energy cycles or independent heat source that used from solar energy or geothermal.The aim of this paper is the investigation of the inlet temperature on thermodynamic performance of the Water-Ammonia combined cycle. In this research, at first, the Ammonia-Water cycle can be modeled with by using of EES software and then the Rankine-thermodynamic gas combined cycle is simulated. Also, the results are studied from the perspective of the first and second law of thermodynamics. Finally, the effect of turbine inlet temperature into the thermodynamic performance is discussed.

In the present study, stress analysis and explicit solution of rectangular plate with arbitrarily located circular hole, subjected to linear normal stresses on two opposite edges, has been investigated. Airy function and hoop stresses occurring at the edge of the circular have been computed. In this method 2D dimension elasticity and Airy stress function was used. The present method for explicit solution and finding airy stress function are stronger and simpler than prior methods. By using Stress function, the stress distribution around circular hole were calculated. By using obtained airy stress relation the stress distribution around the circle was obtained, plotted and compared with distribution of stress (computed by finite element method in Abaqus). This comparison shows the accuracy of this solution method. It has been observed that stress distribution of stress function is independent from hole location and only depends on the hole's size.

The non-asymmetric rolling process of copper and brass wire has been simulated with the Abaqus software. Presented finite element model in this simulation of rolling predicted output curvature and contact surface width in the non-asymmetric mode (in equality of diameter of rollers, the rotational speed of the rollers and the rollers’ surface finish). The material used in this research has strain hardening property. To evaluate of this study, obtained results are compared with analytical results of other researchers. Comparing the good coincidence of these two methods.