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CONTENTS
Volume 9, Number 2, June 2020
 

Abstract
Reinforced aluminum alloy base composites have become increasingly popular for engineering applications, since they usually possess several desirable properties. Recently, Warm Accumulative Roll Bonding (WARB) process has been used as a new novel process to fabricate particle reinforced metal matrix composites. In the present study, Tio2 particles are used as reinforcement in aluminum metal matrix composites fabricated through warm accumulative roll bonding process. Firstly, the raw aluminum alloy 1060 strips with Tio2 as reinforcement particle were roll bonded to four accumulative rolling cycles by preheating for 5 min at 300°C before each cycle. The mechanical and bonding properties of composites have been studied versus different volume contents of Tio2 particles by tensile test, peeling test and vickers micro-hardness test. Moreover, the fracture surface and peeling surface of samples after the tensile test and peeling test have been studied versus different amount of Tio2 volume contents by scanning electron microscopy. The results indicated that the strength and the average vickers micro-hardness of composites improved by increasing the volume content of Tio2 particles and the amount of their elongation and bonding strength decreased significantly.

Key Words
metal-matrix composites; mechanical properties; Tio2 particles; bonding strength

Address
(1) Mohamad Heydari Vini:
Department of Mechanical Engineering, Mobarakeh Branch, Islamic Azad University, Mobarakeh, Isfahan, Iran;
(2) Saeed Daneshmand:
Department of Mechanical Engineering, Majlesi Branch, Islamic Azad University, Isfahan, Iran.

Abstract
The purpose of this study was to observe the trend of compounds release from acrylic resin oral prosthesis when used for drug delivery as well as a restoration. In this study, 10 specimens of heat-cured polymethylmethacrylate material were prepared and loaded with methylene blue biological stain. The specimens were then submerged in vials with 5 ml distilled water for 24 hours. The extraction procedure continued for 4 days, each day the specimens were immersed in another 5 ml distilled water vial. All extracted solutions were analyzed by visible light spectroscopy for absorbance comparison. The statistical results showed that the absorbance values were significantly different in the first day of extraction than the following days. However, there was no statistical difference among the 2nd, 3rd and 4th days of extraction. Biological stain loading to acrylic resin at the mixing stage, and then after extraction in distilled water, showed a burst release during the first day followed by a constant release during the following few days.

Key Words
acrylic resin; drug delivery; maxillary obturator; methylene blue

Address
Department of Dental Technology, College of Health and Medical Technology, Middle Technical University, Baghdad 00964, Iraq.


Abstract
Limit elastic speed analysis of Al/SiC-based functionally graded annular disk of uniform thickness has been carried out for two cases, namely: metal-rich and ceramic rich. In the present study, the unknown field variable for radial displacement is solved using variational method wherein the solution was obtained by Galerkin\'s error minimization principle. One of the objectives was to identify the variation of induced stress in a functionally graded disk of uniform thickness at limit elastic speed using modified rule of mixture by comparing the induced von-Mises stress with the yield stress along the disk radius, thereby locating the yield initiation. Furthermore, limit elastic speed has been reported for a combination of varying grading index (n) and aspect ratios (a/b). Results indicate, limit elastic speed increases with an increase in grading indices. In case of an increase in aspect ratio, limit elastic speed increases up to a critical value beyond which it recedes. Also, the objective was to look at the variation of yield stress corresponding to volume fraction variation within the disk which later helps in material tailoring. The study reveals the qualitative variation of yield stress for FG disk with volume fraction, resulting in the possibility of material tailoring from the processing standpoint, in practice.

Key Words
yield stress calculation; modified rule of mixture (MROM); limit analysis; variational method; FG disk

Address
(1) Royal Madan, Shubhankar Bhowmick:
Department of Mechanical Engineering, National Institute of Technology Raipur (C.G)-492010, India;
(2) Kashinath Saha:
Department of Mechanical Engineering, Jadavpur University, Kolkata 700032, India.

Abstract
In this paper, an improved theoretical interfacial stress and slip analysis is presented for simply supported composite steel-concrete beam bonded with an adhesive. The adherend shear deformations have been included in the present theoretical analyses by assuming a linear shear stress through the thickness of the adherends, while all existing solutions neglect this effect. Remarkable effect of shear deformations of elements has been noted in the results. It is observed that large shear is concentrated and slip at the edges of the composite steel-concrete. Comparing with some experimental results from references, analytical advantage of this improvement is possible to determine the normal and shear stress to estimate exact prediction of normal and shear stress interfacial along span between concrete and steel beam. The exact prediction of these stresses will be very important to make an accurate analysis of the mode of fracture. It is shown that both the normal and shear stresses at the interface are influenced by the material and geometry parameters of the composite steel-concrete beam. This research is helpful for the understanding on mechanical behavior of the connection and design of such structures.

Key Words
analytical solution; adhesive; shear deformations; slip; composite beam; interfacial stress

Address
Laboratory of Geomatics and Sustainable Development, University of Tiaret, Algeria.

Abstract
In this paper, using the recently introduced analytical approach for the analysis of mass and heat transfer during film growth in reactors for epitaxy from the gas phase, these processes are analyzed taking into account natural convection and the possibility of changing the rate of chemical interaction between reagents. As a result of the analysis, the conditions under which the homogeneity of the grown epitaxial layers increases with a change in the values of the parameters of the growth process are formulated.

Key Words
growth; heat transfer; material fabrication; mathematical modelling

Address
(1) E.L. Pankratov:
Mathematical and Natural Science Department, Nizhny Novgorod State University, Russia;
(2) E.L. Pankratov:
Higher Mathematics Department, Nizhny Novgorod State Technical University, Russia.

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