One of the most prominent processes in industry is bending. Rotary draw bending method is known to be the most conventional approach for thin wall tube bending. Pressure die is an effective tool which boosts the tube bending process and eventually improves the bending quality. Other effective parameters include mandrel and the amount of clearance between tube and mandrel. In the present study, the process was modeled by finite element method and the precision of the model was validated via comparing practical results. Subsequently, using the validated model, the effects of pressure die movement and the mandrel and its clearance were investigated. Specifically, the force vicissitudes and bending quality with respect to mandrel clearance and pressure die movement were evaluated. It was shown that reducing the clearance between mandrel and tube, results in force increase while the bending quality was improved. Also it was indicated that the pressure die movement has less effects on process forces and flattening the tube.

In this work, three-dimensional turbulent forced convection flow through a B-Type section pipe, with porous material is inserted at the bottom wall, is investigated numerically. The B-Type section pipe is used in cooling systems, such as cars’ radiator. The main purpose of this research is to enhance heat transfer and to reduce the scales of such systems. The governing equations are formulated according to the volume averaging method. The results are verified by comparing them with some valid numerical data. The dependence of the Nusselt number and pressure drop on the porosity, permeability and Reynolds number are investigated. The results indicate that, at the maximum flow rate, the heat transfer can be enhanced about 8 times by using porous material while the pressure drop is increased about 2.5 times.

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. Their fracture toughness, bending strength and density are measured. Subsequently, it is found that the armour sample made of alumina with V.F. of 10% of SiC particles indicates more desirable properties as compared to other armour samples. Hence, the computer simulation and ballistic tests are carried out using alumina with V.F. of 10% of SiC particles and the results are compared with those of ballistic tests of pure alumina. During the simulation, it is observed that pure alumina with a thickness of 10 mm and aluminum substrate with a thickness of 4.8 mm is broken due to 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 the impact. The ballistic tests were also carried out 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 occurs. It was found that the armour with a ceramic layer thickness of 6 mm did fracture, whereas the others were able to withstand the conditions of the ballistic test.

Nowadays, the non-traditional processes such as LASER, EDM and AWJ, are used for cutting high thickness sheet metal. Hardox is hard and tough steel alloy and it has many industrial applications. One of the best processes to cut the Hardox is abrasive water jet (AWJ) cutting. It can cut complex shapes with high quality and accurate tolerances. AWJ cutting offers certain unique benefits such as negligible heat affected zone, high degree of manoeuvrability in cutting process and less machining force exertion. In this research work, first, the effective cutting process “AWJ” parameters were identified. Then, to determine optimum Hardox cutting parameters, some experimental tests were undergone. Finally, the experimental results were analysed using “ANOVA” technique in order to determine regression equations for achieving optimum parameters to set-up equipment for Hardox steel cutting.

In this research work, a novel parallel manipulator with high positioning and orienting rate is introduced. This mechanism has two rotational and one translational degree of freedom. Kinematics and Jacobian analysis are investigated. Moreover, workspace analysis and optimization has been performed by using genetic algorithm toolbox in Matlab software. Because of reducing moving elements, it is expected much more better dynamic performance with respect to other counterpart mechanisms with the same degrees of freedom. In addition, using couple of cylindrical and revolute joints, increased mechanism ability resulted to have more extended workspace.

This paper deals with the harmonic forced vibration of a circular plate surface bonded by two piezoelectric layers, based on the Kirchhoff plate model. The electric potential field in the piezoelectric layer is assumed such that the Maxwell static electricity equation is satisfied. The differential equations of motion are solved analytically for clamped edge boundary condition of the plate. The solutions are expressed by elementary Bessel functions. The results are verified by those obtained from finite-element analysis as well as the findings stated in the literature.

In this work, nanostructured NiTi shape memory alloy with equal atomic percentage was produced through mechanical alloying. The result exhibited that after 60 h of mechanical alloying of high purity elemental powder mixtures of nickel and titanium by a planetary high-energy ball mill, the Ti dissolved into Ni lattice and NiTi (B2) phase was obtained. The XRD investigations, SEM observations, TEM examinations and microhardness results concluded that this method is a powerful and high productive process for preparing NiTi shape memory alloy with nanocrystalline structure and appropriate morphology.

This paper presents a new methodology for the automated inspection of pipes. Standard inspection systems are based on closed-circuit television cameras which are mounted on remotely controlled robots and connected to remote video recording devices. The main problems of such camera-based inspection systems are: 1) the lack of visibility in the interior of the pipes and 2) the poor quality of the obtained images because of difficult lighting conditions. The focus of this research is the automated detection and location of defects in the internal surface of pipes. The proposed optical system is an assembly of a CCD camera and a laser diode to create a ring-shaped pattern. The camera obtains images of the light projections on the pipe wall. A novel method for extracting and analyzing intensity variations in the obtained images is described. The image data analysis is based on image processing algorithms. Finally, an image of the pipe wall is generated by extracting the intensity information existing in the pipe pictures. Defects and anomalies can be detected using this extracted image

In classical mechanics, considering Hook’s law, stress is a linear function of strain. While in strain gradient theory, stress is a function of strain and strain differentials. In this paper, Novel formulation relating stress and strain and also new boundary conditions are derived based on minimum potential energy principle. In strain gradient theory a length coefficient parameter is defined. This statistical parameter shows that material behaviour in microscopic scale depends on material dimensions. In classical elasticity dependency of the material behaviour on material size could not be described due to the lack of length coefficient parameter. Here also a total stress tensor, different from the Cauchy’s stress tensor, is defined which can be used as a total stress tensor in momentum equation. Using strain gradient theory, strain field for a rotational shaft with a constant angular speed is analytically studied. Knowing displacement field, total stress tensor can also be computed. A material constant is present in the derived displacement field in addition to the two Lame constants. Formulations based on strain gradient theory turn to those of classical mechanics if length coefficient is neglected. Results of stress analysis using strain gradient theory and those of classic mechanics are compared.

There is always a need to increase a distillate output of Solar still. The distillate output of solar stills is expected to increase by applying plates inside solar stills. Hence, an experimental study is conducted to investigate the improvement distillate output of basin solar stills by increasing the effective surface area with the help of different plates. For this purpose, three solar stills are developed by locally available materials. The first solar still is a conventional type, the second is made of Aluminium plate while the third one is made of Galvenized Iron plate. Performance of solar stills having aluminium plate and Galvenized iron plate is tested and compared with conventional solar still under the same climate conditions of Mehsana, Gujarat. The three solar stills are tested at two different situations: still at the same water depth (40 mm) and stills having the same quantity of brackish water (30 L 40 L). Results indicate that, distillate output of solar still having aluminium plate is higher than conventional solar still and solar still having Galvenized iron plate. Moreover, it is found that the average distillate output of water increases up to 45 % and 15 % of conventional solar still with respect to solar stills having aluminium plate and Galvenized iron plate respectively.

This paper deals with failure investigation of boiler feed pump’s shaft of a steam power plant. Boiler feedwater pump is a specific type of pump used to pump, feedwater into a steam boiler and is one of most important part of steam power plants. Feed pumps failure may cause failure of other parts of steam power station, therefore keep them safe, which is an important problem. There are 12 feed pumps in Bandar Abbas power plant. They are old and due to failure of feed pumps because of trying to avoid repetition problem, working condition of 3 dimensional pump’s shaft is modeled with Abaqus software via finite element method analysis. Causes of pump failure and stresses exerted on it are investigated and finally appropriate suggestions such as smooth starting and inverter are proposed.

Deep rolling is a kind of mechanical surface treatments that can improve surface quality, dimensional accuracy and mechanical properties of the parts. Compressive residual stresses generated by the process reduce the tensile stresses during loading into the workpiece. The distribution of residual stress induced by deep rolling can be influenced by rolling parameters; such as overlap of the rolling tracks, friction coefficient between roller and target plate, deep rolling force and deep rolling mechanical tools. In the present research, the effects of these parameters are studied by finite-element simulations. The results indicate that: (I) increasing overlap results in increasing magnitude of the maximum residual stress. (II) Increase in the coefficient of friction results in decrease in the maximum residual stress. However, for coefficient of friction more than 0.1 the effect of friction may lead to contraction. (III) Increase in the force intensity results in increase in the maximum residual stress. (IV) The deep rolling with mechanical tools and spring force provides a higher residual stress than the roller with constant force mode.