INTERNATIONAL JOURNAL OF ADVANCED DESIGN AND MANUFACTURING TECHNOLOGY
Year:2013 | Volume:6 | Issue:3 (24)|Papers Count:12

In design of defence structures, concrete is often used to provide protection against incidental dynamic loadings such as the impact of a steel projectile. In the present study, a new analytical model is proposed to predict penetration depth into concrete targets by ogive nose projectile. Hence, to develop the model and simulate penetration of high velocity ogive-shape nose steel projectiles into concrete targets, several tests have been simulated numerically with the Ls-Dyna finite element code. The results show good agreement between the developed analytical model and the experimental results from other researchers.

This paper presents the findings of experimental investigations into the effects of cutting speed, feed rate, depth of cut and approach angle on the machinability of titanium (Grade-5) alloy. The comparison for two different cutting materials inserts, i.e. polycrystalline diamond (PCD) and cubic boron nitride (CBN) with similar tool geometry for similar machining parameters is also carried out. Design of experiment technique i.e. response surface methodology (RSM) has been used to accomplish the objectives of the experimental study. The experimental plan for four factors at three levels using face centre, and centred composite design (CCD) was employed. The results approved the approach angle as a dominant factor on the surface roughness and the tangential force evaluation as machinability criteria. In comparison to CBN cutting insert, the PCD insert showed better surface finish and smaller cutting force in association with the parameters considered for investigation in machinability study of Titanium (Grade-5) alloy.

An overall treatment with dental implant consist of several essential parts, including a superstructure containing fixture (part of the implant embedding in the bone), abutment (a machined tapered prepared superstructure attached to the fixture), a retainer (which hold the aesthetic portion of the restoration) and the crown (aesthetic part of the restoration). In this common kind of restoration, crown is cemented to metal framework. However, in this research a novel method of design of dental implant is presented which includes only two components: Integrated implant, and Crown. The new design is based on an integrated implant which enables dentist to fit the crown by a snap-fit ringinstantly. In order to carry out stress analysis, the finite element method (FEM) is applied on implant and bones to verify different loading conditions. The results of FEM analysis indicate thatthe proposed design undergoes different loading conditions successfully.

In recent years, 3D imagination of human's organs has become feasible by digital image processing techniques and algorithms via CT or MRI images. In this study, a new method for reverse engineering and biomodelling of hard tissues by CATIA cloud points' concept has been considered. Comparing with the current softwares such as BioBuild or Mimics, the proposed method has demonstrated its easiness of implementing and modelling, final model's high accuracy, easiness of data exchanging with the rapid prototyping systems and reduction of need for having anatomical background to interpret the CT or MRI images.

An industrial gas turbine is able to decrease output power on hot summer days while electricity demand peaks. Steam injection in gas turbines has been used for many years to prevent the loss of performance of gas turbines caused by high ambient temperature. Vodoley system is a Closed Steam Injection Gas Turbine Cycle (CSIGTC), which is known as a self-sufficient in steam production. In this study the influence of steam injection in Mashhad Power Plant GE-F5 gas turbine parameters was experimentally investigated. Moreover a computer modelling has been used to study water balance in a CSIGTC system. The results show that although the system has additional water treatment process, its application increases thermal efficiency up to 35.33 percents for 25 MW of power output at an ambient temperature of 40°C. Also water balance considerations show for a direct contact condenser of 96% efficiency and the exhaust temperature of 420°C at turbine outlet, about 7.8 kg/s of make-up water is needed under ISO rating of gas turbine (101.3 kPa, 15°C) which must be provided for the CSIGTC system. This amount of water is about 51% of injected steam.

The current paper examines the application of finite-time thermodynamics in order to compare the performance between air-standard cycles, i.e. Atkinson, Diesel and Otto cycles with constant specific heats of working fluid. The effects of input temperature and compression ratio on the net output work and efficiency of the Atkinson cycle, Diesel cycle and Otto cycle are analyzed. It is assumed that the compression and power processes are isentropic and any convective, conductive and radiative heat transfer to cylinder wall during the heat rejection process may be ignored. The efficiency of these cycles is compared for equal maximum temperature as well. The findings may present guidance concerning performance evaluation and improvement of practical internal combustion engines.

The aim of this research is to investigate the effect of Carbon Fiber Reinforced Polymer (CFRP) composite fabric on monotonic and fatigue behaviors of reinforced concrete beams. To control the failure occurrence, a small notch was induced at the middle span in bottom surface for all of the studied RC specimens. Totally 12 beams were tested out of which 6 beamswere tested under monotonic loading and the other 6 beams were tested under fatigue cyclic loading. Every group of 6 tested beams consisted of 3 intact and 3 CFRP retrofitted RC beams. Dimensions of the specimens were 150´150´1000 mm and a 150 mm-deep notch was cut at the center of all of the specimens. The experimental examination was conducted to study stresses distributed throughout the critical regions in reinforced concrete and carbon fiber reinforced plastic (CFRP) strengthened RC beams. Fundamentally, these critical regions were cracked zones in CFRP-retrofitted RC beams. Results from monotonic and fatigue tests were compared to each other. In the monotonic test, measurements of shear stress distribution and stiffness were carried out until the failure of the specimens. In the fatigue test, the ceiling of applied load was considered at the level of design service load for bridges. In addition, strain measurements led to the calculation of interfacial shear stresses between concrete substrate and the CFRP layer. The variation of such load cycles are presented and discussed. Load-deflection curves, strain responses and propagation of tensile cracks would provide an insight into the performance of the CFRP strengthened beams subjected to different cycles of fatigue loading.

Superplastic materials show huge amount of deformation in low strain rates and temperature above half of melting point. In superplastic forming, estimating the pressure-time diagram and the thickness distribution has significant importance. Utilizing numerical methods, the involved parameters in superplastic forming can be optimized for such estimations. In the present paper, the simulation of superplastic forming of Ti-6Al-4V alloy for a cup-shape part is demonstrated, assigning the proper constitutive equation. In the following, a noble approach for estimating the pressure-time diagram, using finite element method is presented and by using this approach, the optimum pressure-time diagram for the forming process is estimated, while the effects of process parameters such as friction index and strain rate on pressure-time diagram and thickness distribution is evaluated. Simulation results are compared with other researches results, which confirm satisfactory agreement.

Surface roughness of engineering parts is a very significant property that effectively influences on the wear and fatigue strength as well as bearing load capacity. There are many methods for improving surface quality of engineering parts such as grinding, lapping and honing. Roller Burnishing is one of the techniques for improving surface quality. Roller Burnishing improves surface quality by means of Cold working. It depends on many factors such as RPM of work piece, feed rate of Burnishing tool and the penetration depth of Roller burnishing tool into the work piece. At the present paper, we have tried to investigate the effective factors of Roller Burnishing and optimize them by means of Taguchi approach.

Nowadays, different methods are used to solve the optimization problems. One of the newest methods is BCO, which is inspired of the nature and derived from bee’s interacting with each other. It can be noted that BCO is derived from the bees’ social life. In this paper, the fuzzy logic is used for bee's decision stage. In a nutshell, we solve two different problems that have already been solved by ESO (Evolution Structural Optimization) and BESO (Bi direction Evolution Structural Optimization) methods. In this study we demonstrate that the BCO is able to achieve better solutions and it is quite appropriate even for constrained problems.

A finite volume-lattice Boltzmann algorithm is applied to study skin friction behaviour in different channel flows. For this purpose, cell centred scheme is adapted to discretize the Boltzmann equation and consistent boundary conditions are also addressed, which resulted in a wider domain of stability. A simulation of flow in a two dimensional channels with different geometries are carried out. The results are compared with previous valid results in which favourable agreement was observed. The results showed that skin friction in plane Poiseuille flow converged to 24/Re, but skin friction distribution in suddenly enlarged channels regain symmetry after some distance downstream of the expansion plane.

Implementing a combined cooling, heating and power system (CCHP) to cool, heat and produce electricity is growing rapidly due to its efficiency and low emissions. In this paper, using economic analysis, the size and operation detail of the required gas engine and the specific electricity, cooling and heating load curves for a one year operating period has been determined. The proposed CCHP system meets thermal demands of the facility and has been evaluated under such strategy. Net Annual Profit (NAP) has been introduced as an objective function to be maximized through a developed nonlinear mixed integer programming software. The operation strategy and the payback period of the chosen system have also been determined. A study with the purpose of including or excluding subsidy prices has been carried out. Furthermore, a sensitivity analysis was elaborated in order to show the dependency of optimal solutions to some key contributing factors such as fuel price, electricity buying price and electricity selling price. Results show that, these parameters have significant effect on the system’s performance.