Reza Azarafza Articles List

List of Articles Reza Azarafza

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1 - Impact Behavior of Ceramic-Metal Armour by Al2O3-Nano SiC Nano Composite
reza azarafza Ali Arab Ali Mehdipoor Ali Davar

Abstract: Alumina (Al2O3) is one of the most practical ceramics used in making ceramic-metal armours. To improve the properties of alumina, some other materials are added to it. In this paper, SiC material as Nano powder is added to alumina, and four armour samples of t More

Abstract: Alumina (Al2O3) is one of the most practical ceramics used in making ceramic-metal armours. To improve the properties of alumina, some other materials are added to it. In this paper, SiC material as Nano powder is added to alumina, and four armour samples of this new ceramic with different volume fractions (V.F. ) including 0%, 5%, 10% and 15% of SiC particles are made. Then, the samples are warmed up by hot press and their fracture toughness, bending strength and density are measured. Then, it is found that the armour sample made of alumina with V.F. of 10% of SiC particles shows more desirable properties as compared to the other armour samples. So, the computer simulation and ballistic test are done using alumina with V.F. of 10% of SiC particles and the obtained results are compared with those of ballistic test of pure alumina. In the simulations, it is observed that the pure alumina with the thickness of 10 mm and aluminum substrate of thickness 4.8 mm is broken due to the normal impact of a projectile with 800 m/s speed, but the new armour made of the present new ceramic is able to withstand the same conditions and no fracture is observed after impact. The ballistic tests were also done using the present new ceramic-Aluminum armour samples with ceramic thicknesses of 6, 8 and 10 mm, respectively to determine the smallest thickness at which the fracture is occurred. It was found that the armour with the ceramic layer thickness of 6 mm got fractured, whereas the others were able to withstand the conditions of the ballistic test. Manuscript profile
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2 - Free Chattering Fuzzy Sliding Mode Controllers to Robotic Tracking Problem
reza azarafza SAEED MOHAMMAD Hoseni MOHAMMAD FARROKHI

Sliding mode control (SMC) is a powerful approach to solve the tracking problem for dynamical systems with uncertainties. However, the traditional SMCs introduce actuator chattering phenomenon which performs a desirable behavior in many physical systems such as servo co More

Sliding mode control (SMC) is a powerful approach to solve the tracking problem for dynamical systems with uncertainties. However, the traditional SMCs introduce actuator chattering phenomenon which performs a desirable behavior in many physical systems such as servo control and robotic systems, particularly, when the zero steady state error is required. Many methods have been proposed to eliminate the chattering from SMCs which use a finite DC gain controller. Although these methods provide a free chattering control but they deals with only the steady state error and are not able to reject input disturbances. This paper presents a fuzzy combined control (FCC) using appropriate PID and SMCs which presents infinite DC gain. The proposed FCC is a free chattering control which guarantees a zero steady state error and rejects the disturbances. The stability of the closed loop system with the proposed FCC is also proved using Lyapunov stability theorem. The proposed FCC is applied to a two degree of freedom robot manipulator to illustrate effectiveness of the proposed scheme. Manuscript profile
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3 - Dynamic Analysis of Carbon Nanotube-Reinforced Multilayer Composite Plates
Jamshid Ebrahimi Jafar Eskandari Jam Reza Azarafza Mohsen Heydari Beni Majid Eskandari Shahraki
10.30495/admt.2021.1905074.1206

The paper studied the analysis of vibrations of rectangular carbon nanotube-reinforced composite plates. To this end, a three-layer nanocomposite plate - two layers with the targeted distribution of carbon nanotubes as FG-X at the top and bottom and a layer without an a More

The paper studied the analysis of vibrations of rectangular carbon nanotube-reinforced composite plates. To this end, a three-layer nanocomposite plate - two layers with the targeted distribution of carbon nanotubes as FG-X at the top and bottom and a layer without an amplifier in the middle of the plate - were analyzed. The governing equations for this problem are based on First-order Shear Deformation Theory (FSDT). The distribution of nanotubes on these plates is as targeted FG-X. The effect of various types of SWCNTs distributions in the direction of thickness on the vibrational behavior of nanocomposite plates was examined. The effective properties of nanocomposite materials Functionally Graded Carbon Nanotube-Reinforced Composite (FG-CNTRC) were estimated using the rule of mixtures. Detailed parametric studies were performed to determine the effects of the volume fraction of carbon nanotubes and the thickness-to-length ratio of the plate on the natural frequency responses and the shape of the plate mode. The equations obtained in this problem were coded in MATLAB software, the nanocomposite plate was modelled in ABAQUS software, and the comparison of the results obtained from the numerical solution with ABAQUS software showed relatively right consistency with the results obtained from the analytical solution. Manuscript profile
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4 - Dynamic Response of FGM Plates Under Blast Load
reza azarafza puya pirali Ali Davar majid ghadimi
10.30486/admt.2021.1920150.1239

The present study investigates the deformation of FGM plates under blast load. Hamilton's principle is used to obtain the dynamic Equations. The two constituent phases, ceramic and metal, vary across the wall thickness according to a prescribed power law. Boundary condi More

The present study investigates the deformation of FGM plates under blast load. Hamilton's principle is used to obtain the dynamic Equations. The two constituent phases, ceramic and metal, vary across the wall thickness according to a prescribed power law. Boundary conditions are assumed to be Simply Supported (SS). The type of explosive loading considered is a free in-air spherical air burst and creates a spherical shock wave that travels radially outward in all directions. For the pressure time of the explosion loading, Friedlander’s exponential relation has been used. In order to determine the response analytically, the stress potential field function is considered. Using the Galerkin method, the final Equations are obtained as nonlinear and nonhomogeneous second-order differential Equations. The effect of temperature including thermal stress resultants and different parameters on the dynamic response have been investigated. Results have been compared with references and validated. Results showed that the amplitude of the center point deflection of the FGM plate is less than the pure metal plates when exposed to blast load, by increasing the volumetric index percentage of FGM, center point deflection is increased and in the FGM plates, deformation of symmetrical plates is smaller than the asymmetric plates. Also by applying the damping coefficient of the FGM plates, the amplitude of center point deflection is reduced, and by increasing the aspect ratio of the FGM plate, its center point deflection against explosion waves is reduced and by considering the effects of thermal resultant forces and moments, center point deflection is increased. Manuscript profile
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5 - Analysis of FGM Cylindrical Shell under Impact Loading of Explosion
reza azarafza puya pirali Ali Javadi
10.30486/admt.2023.1967386.1378

Due to the increasing application of Functionally Graded Materials (FGM) shells, it seems necessary to investigate their behaviour under different loads. Therefore, in this paper, the dynamic response of functionally graded materials cylindrical shells under explosive l More

Due to the increasing application of Functionally Graded Materials (FGM) shells, it seems necessary to investigate their behaviour under different loads. Therefore, in this paper, the dynamic response of functionally graded materials cylindrical shells under explosive load has been investigated with analytical and simulation methods. LS-DYNA software is used in the simulation method. In analytical solution, vibration of composite circular cylindrical shells is investigated based on the first-order deformation shell theory. The boundary conditions are assumed to be fully simply supported. The dynamic response of composite shells is studied under blast loading. The modal technique is used to develop the analytical solution of composite shell. The solution for the shell under the giving loading condition can be found using the convolution integral. Material properties are assumed to be graded in the thickness direction according to Reddy function. A FGM cylindrical shell is made up of a mixture of ceramic and metal. Results show that the effect of explosion is such that it has the greatest effect on the inner layer and with increasing thickness to the outside of the shell this effect decreases and when the maximum deflection occurs, the dynamic velocity is zero. Also, it was observed that with increasing length, the radial deflection increases due to increasing the distance from the support to the center of the shell. Manuscript profile

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List of Articles Reza Azarafza