ISRN Mechanical Engineering http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. Rolling Bearing Fault Diagnosis Based on Physical Model and One-Class Support Vector Machine Mon, 14 Apr 2014 09:25:05 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2014/160281/ This paper aims at diagnosing the fault of rolling bearings and establishes the system of dynamics model with the consideration of rolling bearing with nonlinear bearing force, the radial clearance, and other nonlinear factors, using Runge-Kutla such as Hertzian elastic contactforce and internal radial clearance, which are solved by the Runge-Kutta method. Using simulated data of the normal state, a self-adaptive alarm method for bearing condition based on one-class support vector machine is proposed. Test samples were diagnosed with a recognition accuracy over 90%. The present method is further applied to the vibration monitoring of rolling bearings. The alarms under the actual abnormal condition meet the demand of bearings monitoring. Li Xiangyang and Chen Wanqiang Copyright © 2014 Li Xiangyang and Chen Wanqiang. All rights reserved. Determining Transmission Coefficient of Propagating Solitary Wave over Trapezoidal Breakwater and Parametric Studies on Different Influential Factors Thu, 10 Apr 2014 13:28:25 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2014/841327/ The objective of this study is to numerically investigate transmission coefficient of submerged trapezoidal breakwater of various configurations subjected to solitary waves. Boussinesq equations of Madsen and Sorensen are applied as governing equations for simulation purposes. Discretization of governing equations is accomplished using Galerkin finite element method and Adams-Bashforth-Moulton predictor-corrector method is considered for time integration. In order to obtain transmission coefficients, two gauges are considered before and after the submerged breakwater to record initial and transmitted wave heights, respectively. To examine the effect of configuration of breakwaters on their transmission coefficients, submergence ratio and crest width ratio are defined and analyzed. Different submergence ratios and various crest width ratios are considered. Computed results indicate how transmission coefficient decreases with the increase over different ranges of crest width ratio, for all values of submergence ratio. Furthermore, keeping crest width and submergence ratios constant, solitary waves with higher initial heights are simulated. Results of simulation indicate that transmission coefficient becomes higher for the same breakwater characteristics. Finally, a parametric study is conducted on the effect of side slopes of breakwaters. It is shown that side slopes have strong effect on wave transmission. Amin Rahimzadeh, Parviz Ghadimi, Mohammad A. Feizi Chekab, and Mohammad H. Jabbari Copyright © 2014 Amin Rahimzadeh et al. All rights reserved. Prediction of Waste Heat Energy Recovery Performance in a Naturally Aspirated Engine Using Artificial Neural Network Sun, 30 Mar 2014 09:44:36 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2014/240942/ The waste heat from exhaust gases represents a significant amount of thermal energy, which has conventionally been used for combined heating and power applications. This paper explores the performance of a naturally aspirated spark ignition engine equipped with waste heat recovery mechanism (WHRM). The experimental and simulation test results suggest that the concept is thermodynamically feasible and could significantly enhance the system performance depending on the load applied to the engine. The simulation method is created using an artificial neural network (ANN) which predicts the power produced from the WHRM. Safarudin Gazali Herawan, Abdul Hakim Rohhaizan, Azma Putra, and Ahmad Faris Ismail Copyright © 2014 Safarudin Gazali Herawan et al. All rights reserved. The Effect of Nanoparticles on Thermal Efficiency of Double Tube Heat Exchangers in Turbulent Flow Thu, 27 Mar 2014 11:26:49 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2014/274560/ This paper refers to the Overall Heat Transfer Coefficient of Nano Fluids (OHTCNF) in heat exchangers and the relevant effective parameters. An improvement in Heat Transfer (HT) and OHTCNF containing nanoaluminum oxide with ca. 20 nm particle size and particular volume fraction in the range of 0.001-0.002 has been reported. The effects of temperature and concentration of nanoparticles on HT variation as well as Overall Heat Transfer Coefficient (OHTC) in a countercurrent double tube heat exchanger with turbulent flow have been studied. The experimental results show a remarkable 8%–10% rise in the mean HT and the OHTC. Accordingly, with an increase in the processing temperature and/or particle concentration the OHTC was observed to increase. Reza Aghayari, Heydar Madah, Bahram Keyvani, Abdolreza Moghadassi, and Fatemeh Ashori Copyright © 2014 Reza Aghayari et al. All rights reserved. Cycle Time Reduction in Injection Molding Process by Selection of Robust Cooling Channel Design Tue, 25 Mar 2014 09:27:38 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2014/968484/ Cycle time of a part in injection molding process is very important as the rate of production and the quality of the parts produced depend on it, whereas the cycle time of a part can be reduced by reducing the cooling time which can only be achieved by the uniform temperature distribution in the molded part which helps in quick dissipation of heat. Conformal cooling channel design is the solution to the problem which basically “conforms” to the shape of cavity in the molds. This paper describes the analytical study of cooling analysis of different types of cooling channel designs. The best cooling channel design is also selected on the basis of minimum time to reach ejection temperature, uniform temperature distribution, and minimum warpage of part. “Creo Elements/Pro 5.0” is used to model the case study, its molds, and the cooling circuit whereas analytical study is done using “Autodesk Moldflow Advisor 2013 (AMFA).” Muhammad Khan, S. Kamran Afaq, Nizar Ullah Khan, and Saboor Ahmad Copyright © 2014 Muhammad Khan et al. All rights reserved. Performance of Pulverized Coal Combustion under High Temperature Air Diluted by Steam Tue, 25 Mar 2014 07:49:33 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2014/217574/ The high temperature air combustion (HiTAC) is an advanced promising technology for heat recovery, energy saving, and stability improvement of flame. Computational fluid dynamic (CFD) is known as an applied tool to execute HiTAC modeling. In this paper, performances of pulverized coal combustion under the high preheated and oxygen deficient air are studied by both experimental and numerical methodology. The experimental facilities have been accomplished in a HiTAC chamber with coal injection velocity that ranges from 10 to 40 m/s. In order to achieve different preheated temperatures, the combustion air in such system is diluted by variable steam percentages from 0 to 44%. Results of mathematical simulation and experimental tests present convincible agreement through whole region. It is concluded that emission is reduced by increasing the steam percentage in the oxidizer due to decreasing the flame temperature. Besides, graphical contours show that by adding more steam to oxidizer composition, the oxygen concentration decreased. Additionally, results show that when the injection speed of fuel is increased, emission is also increased, and when the injection rate of preheated air is increased, emission shows decreasing trend. Further contribution in future is needed to investigate the performance of such technologies. Mohsen Saffari Pour and Yang Weihong Copyright © 2014 Mohsen Saffari Pour and Yang Weihong. All rights reserved. Equilibrium, Kinetics, and Thermodynamics of Remazol Brilliant Blue R Dye Adsorption onto Activated Carbon Prepared from Pinang Frond Sun, 23 Mar 2014 09:33:34 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2014/184265/ The adsorption of remazol brilliant blue R (RBBR) dye on pinang frond based activated carbon (PF-AC) was investigated in a batch process. The effects of initial dye concentration, contact time, solution temperature, and solution pH were evaluated. The adsorption equilibrium and kinetic were found to follow Freundlich isotherm models and pseudo-second-order kinetic model, respectively. The mechanism of the adsorption process was found from the intraparticle diffusion model. Result from adsorption thermodynamic show that interaction for RBBR dye was found to be feasible, nonspontaneous, and endothermic. The results indicated that the PF-AC is very effective for the RBBR adsorption from aqueous solution. Mohd Azhar Ahmad, Safarudin Gazali Herawan, and Ahmad Anas Yusof Copyright © 2014 Mohd Azhar Ahmad et al. All rights reserved. Springback of Friction Stir Welded Sheets Made of Aluminium Grades during V-Bending: An Experimental Study Tue, 18 Mar 2014 11:20:36 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2014/681910/ The main aim of the present work is to study the effect of shoulder diameter, rotational speed, and welding speed on the springback performance of friction stir welded sheets. The friction stir welded sheets are made by welding 6061T6 to 5052H32, and 6061T6 to 6061T6. The springback has been evaluated after V-bending of welded sheets, involving pure bending. The relation between springback and weld zone properties like yield strength, Young’s modulus, yield strength to Young’s modulus ratio, and strain hardening exponent is identified. It is found that, with increase in shoulder diameter, rotational speed, and welding speed, the springback of friction stir welded sheets has reduced, and is independent of the material combinations. The relation between springback and weld properties change coincides with existing knowledge about springback. The friction stir welded sheets show better springback performance as compared to 6061T6 base material, but inferior to 5052H32 base material. By reducing the punch nose radius, the springback of friction stir welded sheets can be minimized. It is also concluded that, by proper tailoring of Al grades, and by alteration of weld zone properties through friction stir welding, the springback of friction stir welded sheets can be reduced considerably. B. Durga Rao and R. Ganesh Narayanan Copyright © 2014 B. Durga Rao and R. Ganesh Narayanan. All rights reserved. Travel-Time Difference Extracting in Experimental Study of Rayleigh Wave Acoustoelastic Effect Mon, 17 Mar 2014 09:54:08 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2014/349020/ In order to identify the travel-time difference accurately in the experimental study of Rayleigh wave acoustoelastic effect, an experimental system is constructed by the ultrasonic pulser-receiver, digital oscilloscope, Rayleigh wave transmitter and receiver, and a personal computer. And then, the digital correlation method and the Fourier transform frequency analysis method are used to obtain the travel-time difference of the Rayleigh wave corresponding to different subsurface stress conditions. Furthermore, the simulated ultrasonic signals are used to verify the reliability of the two kinds of ultrasonic signal information extracting algorithms, respectively. Finally, the proposed signal processing methods are applied to extract the time delay between different Rayleigh wave signals corresponding to different subsurface stress level. Hu Eryi and Ying Shao Copyright © 2014 Hu Eryi and Ying Shao. All rights reserved. Elastic Analysis of Rotating Thick Truncated Conical Shells Subjected to Uniform Pressure Using Disk Form Multilayers Mon, 17 Mar 2014 08:00:00 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2014/764837/ Using disk form multilayers, an elastic analysis is presented for determination of displacements and stresses of rotating thick truncated conical shells. The cone is divided into disk layers form with their thickness corresponding to the thickness of the cone. Due to the existence of shear stress in the truncated cone, the equations governing disk layers are obtained based on first shear deformation theory (FSDT). These equations are in the form of a set of general differential equations. Given that the truncated cone is divided into n disks, n sets of differential equations are obtained. The solution of this set of equations, applying the boundary conditions and continuity conditions between the layers, yields displacements and stresses. The results obtained have been compared with those obtained through the analytical solution and the numerical solution. Mohammad Zamani Nejad, Mehdi Jabbari, and Mehdi Ghannad Copyright © 2014 Mohammad Zamani Nejad et al. All rights reserved. Estimate Lateral Tire Force Based on Yaw Moment without Using Tire Model Mon, 03 Mar 2014 11:18:58 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2014/934181/ This paper demonstrates the implementation of a model-based vehicle estimator, which can be used for lateral tire force estimation without using any highly nonlinear tire-road friction models. The lateral tire force estimation scheme has been designed, and it consists of the following three steps: the yaw moment estimation based on a disturbance observer, the sum of the lateral tire force of two front tires and two rear tires estimation based on a least-square method, and individual lateral tire force estimation based on a heuristic method. The proposed estimator is evaluated under two typical driving conditions and the estimation values are compared with simulator data from CarSim and experimental data provided by GM. Results to date indicate that this is an effective approach, which is considered to be of potential benefit to the automotive industry. Jun Yang, Wuwei Chen, and Yan Wang Copyright © 2014 Jun Yang et al. All rights reserved. Exact Solution of Thermoelastic Problem for a One-Dimensional Bar without Energy Dissipation Tue, 04 Feb 2014 13:09:57 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2014/694259/ We consider a homogeneous isotropic thermoelastic half-space in the context of the theory of thermoelasticity without energy dissipation. There are no body forces or heat source acting on the half-space. The surface of the half-space is affected by a time dependent thermal shock and is traction free. The Laplace transform with respect to time is used. The inverse transforms are obtained in an exact manner for the temperature, thermal stress, and displacement distributions. These solutions are represented graphically and discussed for several cases of the applied heating. Comparison is made between the predictions here and those of the theory of thermoelasticity with one relaxation time. A. M. Abd El-Latief and S. E. Khader Copyright © 2014 A. M. Abd El-Latief and S. E. Khader. All rights reserved. Effect of Density and Pointed Corner Degree of Pore on Local Stress in Welded Structures: Defect in Marine Structures Thu, 16 Jan 2014 09:05:12 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2014/834659/ The process of assembly by welding, in marine structures, led to the creation of microstructural heterogeneities zones. Welded structures generally contain defects such as lack of penetration, slag inclusion, porosity, and misalignment. Generally these zones can be discontinuities geometrical. At the origins of stress concentration, these regions are favourable sites where fatigue cracks can initiate and propagate. In this study, the 3D finite element method is used to analyze the distribution of stress (strain) generated by the presence in the weld nugget of a pore formed during the welding process. This analysis was made in the matrix-pore interface. The effects of density and pointed corner degree of pore on the stress levels were also analyzed. Farida Bouafia, Boualem Serier, Nassim Serier, and Sardar Sikandar Hayat Copyright © 2014 Farida Bouafia et al. All rights reserved. Erratum to “Verification, Validation, and Testing of Kinetic Mechanisms of Hydrogen Combustion in Fluid-Dynamic Computations” Thu, 02 Jan 2014 16:14:05 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2014/824029/ Victor P. Zhukov Copyright © 2014 Victor P. Zhukov. All rights reserved. Numerical Study of Flutter of a Two-Dimensional Aeroelastic System Sun, 08 Dec 2013 14:20:37 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2013/127123/ This paper deals with the problem of the aeroelastic stability of a typical aerofoil section with two degrees of freedom induced by the unsteady aerodynamic loads. A method is presented to model the unsteady lift and pitching moment acting on a two-dimensional typical aerofoil section, operating under attached flow conditions in an incompressible flow. Starting from suitable generalisations and approximations to aerodynamic indicial functions, the unsteady loads due to an arbitrary forcing are represented in a state-space form. From the resulting equations of motion, the flutter speed is computed through stability analysis of a linear state-space system. Riccy Kurniawan Copyright © 2013 Riccy Kurniawan. All rights reserved. A Critical Review of Computational Methods and Their Application in Industrial Fan Design Tue, 12 Nov 2013 10:00:54 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2013/625175/ Members of the aerospace fan community have systematically developed computational methods over the last five decades. The complexity of the developed methods and the difficulty associated with their practical application ensured that, although commercial computational codes date back to the 1980s, they were not fully exploited by industrial fan designers until the beginning of the 2000s. The application of commercial codes proved to be problematic as, unlike aerospace fans, industrial fans include electrical motors and other components from which the flow will invariably separate. Consequently, industrial fan designers found the application of commercial codes challenging. The decade from 2000 to 2010 was focused on developing techniques that would facilitate converged solutions that predicted the fans’ performance characteristics over the stable part of their operating range with reasonable accuracy, using a practical computational effort. In this paper, we focus on elucidating aspects of the flow physics that one cannot easily study in a laboratory environment, discussing the challenges involved and the relative merits of the available modelling techniques. The paper ends with a discussion of the practical problems associated with the use of commercial codes in a development environment and finally the legislation that is driving the need for aerospace style computation methods. Alessandro Corsini, Giovanni Delibra, and Anthony G. Sheard Copyright © 2013 Alessandro Corsini et al. All rights reserved. Springback Analysis in Sheet Metal Forming Using Modified Ludwik Stress-Strain Relation Sun, 03 Nov 2013 13:41:22 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2013/640958/ This paper deals with the springback analysis in sheet metal forming using modified Ludwik stress-strain relation. Using the deformation theory of plasticity, formulation of the problem and spring back ratio is derived using modified Ludwik stress strain relationship with Tresca and von Mises yielding criteraia. The results have been representing the effect of different value of or ratio, different values of Strain hardening index (), Poisson’s ratio (), and thickness on spring back ratio (). The main aim of this paper is to study the effects of the thickness, ratio, and Poisson’s ratio in spring back ratio. Sanjay Kumar Patel, Radha Krishna Lal, J. P. Dwivedi, and V. P. Singh Copyright © 2013 Sanjay Kumar Patel et al. All rights reserved. Stress Intensity Factors for Cracked Finite Plates with Mixed Boundary Condition Tue, 08 Oct 2013 11:47:15 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2013/471458/ The mixed boundary problems for finite plates with one crack or two collinear cracks are studied. Complex stress functions that satisfy the equilibrium equations and compatibility conditions in the cracked plate as well as the stress condition on crack surfaces are presented. Four models, that is, a square plate with one crack or with two collinear cracks and an airfoil-shaped plate with one crack or with two collinear cracks, are established. The unknown coefficients of the complex stress functions are determined by using boundary collocation method (BCM). The effects of crack orientation, crack distance, and boundary condition on SIFs are investigated by combining with BCM, and the corresponding photoelastic experiments are conducted. The test results generally agree with the BCM calculation results. Zheyuan Hu, Zheming Zhu, Ruoqi Feng, and Rong Hu Copyright © 2013 Zheyuan Hu et al. All rights reserved. Modeling of Homogeneous Mixture Formation and Combustion in GDI Engine with Negative Valve Overlap Wed, 02 Oct 2013 17:52:58 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2013/521375/ Mixture homogeneity plays a crucial role in HCCI engine. In the present study, the mixture homogeneity was analysed by three-dimensional engine model. Combustion was studied by zero-dimensional single zone model. The engine parameters studied include speed, injector location, valve lift, and mass of fuel injected. Valve lift and injector location had less impact on mixture formation and combustion phasing compared to other parameters. Engine speed had a noticeable effect on mixture homogeneity and combustion characteristics. M. K. Lalith, Akshay Dinesh, S. Unnikrishnan, Akhil Radhakrishnan, S. Srihari, and V. Ratna Kishore Copyright © 2013 M. K. Lalith et al. All rights reserved. A Functional Representation Model Facilitating Design Space Expansion Tue, 01 Oct 2013 10:20:26 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2013/686402/ This paper addresses the functional representation based on the event model. In the event model, the ontology is defined based on the theory of propositional logic to describe the connotation of the event, and the variant is defined based on the theories of domain relational calculus and set theory to express the variation range of the event, which is alterable part of the event under the constraints of the ontology. Function is an important concept in conceptual design and has its connotation and extension. The functional representation is proposed based on the event model. The ontology of event is used to describe the connotation of function and to reflect the stability of function. The variant of the event is used to represent the extension and to incarnate the variety of function. The extension of function is the change range of function under the constraints of the connotation. The proposed functional representation divides the function into the immutable part and the alterable part, facilitating the expansion of design space. A functional reasoning model is also put forward based on the event model to support the function reasoning on the computers. Finally, a simple case validates the feasibility of the model. Wei Xu, Ke Zhao, Yatao Li, and Peitao Cheng Copyright © 2013 Wei Xu et al. All rights reserved. Numerical Modeling of the Flow in a Vaneless Diffuser of Centrifugal Compressor Stage Tue, 24 Sep 2013 15:42:07 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2013/602384/ This paper presents the results of numerical investigation of the flow in a vaneless diffuser of centrifugal compressor stage. Simulations were performed using both a commercial CFD package ANSYS CFX and the own-designed computer program. Steady conditions involving SST turbulence model were used for the calculations using CFX. To consider the interaction between impeller and diffuser, not just a diffuser but the whole stage was calculated. The own-designed methodology is based on solving of conservation equations with assumptions that flow in a diffuser is steady state and axisymmetric. The flow area is divided into the flow core and boundary layers. Results of calculation were compared with experimental data. Mykola Kalinkevych and Oleg Shcherbakov Copyright © 2013 Mykola Kalinkevych and Oleg Shcherbakov. All rights reserved. The Flow Simulation and Experimental Study of a Large Low-Head Mixed-Flow Pumping System Sun, 22 Sep 2013 12:06:06 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2013/128326/ A large low-head mixed-flow pumping system has been carried out based on numerical analysis of a three-dimensional viscous flow. For analysis, the Reynolds-averaged Navier-Stokes equations with a Shear stress transport turbulence model were discretized by finite-volume approximations. The result has shown that the flow in the double-helix volute passage is a spiral movement combining axial and rotary flows; the static pressure distribution in the volute is symmetric; the uniformity of axial velocity distribution and velocity-weighted average swirl angle at the outlet section is relatively low. The static pressure decreases gradually from the blade inlet to the exit on the pressure side, while increasing gradually on the suction side. The axial forces decrease gradually with the decrease of lifting head, and the radial forces decrease first and then increase. The pressure fluctuation at certain sections of the pumping system was measured from the model test. It is concluded that the pressure pulsations of impeller inlet and “” back wall of inlet passage are little influenced by operating condition. The domain frequency of the impeller inlet is approximately equal to the rotation frequency, while that of double-helix volute passage is multiple relations with the rotation frequency. Fan Yang and Chao Liu Copyright © 2013 Fan Yang and Chao Liu. All rights reserved. Processing and Properties of Nanocrystalline CoCrFeNiCuAlTiXVMo High Entropy Alloys by Mechanical Alloying Thu, 19 Sep 2013 11:50:29 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2013/167869/ Fabrication of nanocrystalline equiatomic high entropy alloys is a crucial aspect for the product of many tools. The present study describes the synthesis of nanocrystalline equiatomic CoCrFeNiCuAlTiXVMo (X = Zn, Mn) high entropy alloys by mechanical alloying and their characterization by XRD and SEM. The CoCrFeNiCuAlTiXVMo (X = Zn, Mn) high entropy alloys have BCC solid solution with crystallite size less than 10 nm. These alloys are stable even after annealing at 600°C for 1 h. The hardness of the high entropy alloys is found to be 7.6 and 6.2 GPa, respectively. É. Fazakas, B. Varga, and L. K. Varga Copyright © 2013 É. Fazakas et al. All rights reserved. Cauchy Six-Dimensional Formalism for Lamb Waves in Multilayered Plates Mon, 16 Sep 2013 08:54:27 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2013/698706/ Propagation of Lamb waves in multilayered elastic anisotropic plates is studied in the framework of combination of the six-dimensional Cauchy formalism and the transfer matrix method. The closed form secular equations for dispersion curves of Lamb waves propagating in multilayered plates with arbitrary elastic anisotropy are obtained. Sergey V. Kuznetsov Copyright © 2013 Sergey V. Kuznetsov. All rights reserved. Scan and Paint: Theory and Practice of a Sound Field Visualization Method Tue, 27 Aug 2013 14:49:22 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2013/241958/ Sound visualization techniques have played a key role in the development of acoustics throughout history. The development of measurement apparatus and techniques for displaying sound and vibration phenomena has provided excellent tools for building understanding about specific problems. Traditional methods, such as step-by-step measurements or simultaneous multichannel systems, have a strong tradeoff between time requirements, flexibility, and cost. However, if the sound field can be assumed time stationary, scanning methods allow us to assess variations across space with a single transducer, as long as the position of the sensor is known. The proposed technique, Scan and Paint, is based on the acquisition of sound pressure and particle velocity by manually moving a P-U probe (pressure-particle velocity sensors) across a sound field whilst filming the event with a camera. The sensor position is extracted by applying automatic color tracking to each frame of the recorded video. It is then possible to visualize sound variations across the space in terms of sound pressure, particle velocity, or acoustic intensity. In this paper, not only the theoretical foundations of the method, but also its practical applications are explored such as scanning transfer path analysis, source radiation characterization, operational deflection shapes, virtual phased arrays, material characterization, and acoustic intensity vector field mapping. Daniel Fernández Comesaña, Steven Steltenpool, Graciano Carrillo Pousa, Hans-Elias de Bree, and Keith R. Holland Copyright © 2013 Daniel Fernández Comesaña et al. All rights reserved. Contact Analysis of a Dry Friction Clutch System Sun, 25 Aug 2013 15:12:12 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2013/495918/ The numerical simulation of the friction clutch system (pressure plate, clutch disc, and flywheel) during the full engagement period (assuming no slipping between contact surfaces) is carried out using finite element method. Two types of load condition considered affect on the clutch elements during the full engagement period are the contact pressure of diaphragm spring and the centrifugal force. The study of the pressure distribution between the contact surfaces and the factors affecting it is one of the fundamentals in the process of designing the friction clutch to obtain accurate estimation of the temperature distribution during the slipping period and the contact stresses during the full engagement period. The investigation covers the effect of the contact stiffness factor FKN on the pressure distribution between contact surfaces, stresses, and penetration. The penalty and augmented Lagrange algorithms have been used to obtain the pressure distribution between contact surfaces. ANSYS13 software has been used to perform the numerical calculation in this paper. Oday I. Abdullah and Josef Schlattmann Copyright © 2013 Oday I. Abdullah and Josef Schlattmann. All rights reserved. Plastic Constitutive Model and Analysis of Flow Stress of 40Cr Quenched and Tempered Steel Mon, 05 Aug 2013 11:02:36 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2013/490750/ To solve the problem of the accuracy of the numerical simulations of cold rolling, the thermomechanical responses of 40Cr under uniaxial compression loading are presented. The strain rates include quasistatic (0.004 s−1) at temperature of 293 K and dynamic loading regime (632 s−1~5160 s−1) at temperature regime (293 K~673 K). Significant strain rate and temperature sensitivity are measured. Based on these observations, the Johnson-Cook phenomenological constitutive model is proposed to predict the mechanical behavior of the 40Cr over wide ranges of strain rate and temperature. The solution process of the equation parameters is given. Correlations with this Johnson-Cook model are shown very close to the observed responses. Important material parameters are provided to the application of numerical analysis in project. Wang Xiao-qiang, Zhu Wen-juan, Cui Feng-kui, and Li Yu-xi Copyright © 2013 Wang Xiao-qiang et al. All rights reserved. Optimum Conditions for Maximum Power of a Direct Methanol Fuel Cell Mon, 05 Aug 2013 08:05:16 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2013/872873/ It is well known that anode and cathode pressures and cell temperature are the effective parameters in performance of Direct Methanol Fuel Cell (DMFC). In the present study, the genetic algorithm as one of the most powerful optimization tools is applied to determine operating conditions which result in the maximum power density of a DMFC. A quasi-two-dimensional, isothermal model is presented to determine maximum power of a DMFC. For validation of this model, the results of the model are compared to experimental results and shown to be in good agreement with them. Mojtaba Tafaoli-Masoule, Arian Bahrami, and Danial Mohammadrezaei Copyright © 2013 Mojtaba Tafaoli-Masoule et al. All rights reserved. Numerical Hydroacoustic Analysis of NACA Foils in Marine Applications and Comparison of Their Acoustic Behavior Tue, 30 Jul 2013 08:43:16 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2013/714363/ One of the most important parameters to be considered in the design process of lifting surfaces for marine applications is the acoustic noise emitted by the designed surface. In the present work, the hydroacoustic fields of NACA0012 and NACA0018 hydrofoils are calculated, and the acoustic behavior of these sections is examined and compared at different angles of attack. The Ansys-CFX Navier-Stokes solver is used for hydrodynamic analysis, and a highly accurate multithread program named ACOPY is developed in Python programming language based on the Ffowcs Williams and Hawkings method for acoustic analysis. The developed code has high capability in parallel programming. Results of hydrodynamic and acoustic analyses have been validated against available data. A parametric study is conducted, and the best integration surface for FW-H method is introduced. The acoustic behavior of the sections is calculated in an extensive parametric study for different angles of attack of the hydrofoils. The operational acoustic fields of the foils have been calculated and compared. The results indicate that NACA0012 hydrofoil is a better choice and, more effective, when the acoustic behavior of the hydrofoil is a significant design criterion. Parviz Ghadimi, Saman Kermani, and Mohammad A. Feizi Chekab Copyright © 2013 Parviz Ghadimi et al. All rights reserved. Multiobjective Optimization Design for Skew and Sweep Parameters of Two-Stage Blades of Axial Fan Sun, 23 Jun 2013 12:42:25 +0000 http://www.hindawi.com/journals/isrn.mechanical.engineering/2013/274135/ Computer aided design and numerical simulation have been widely applied in optimization design of fan blades. In this paper, skew and sweep parameters of two-stage blades of an axial fan are optimized by using the particle swarm optimization algorithm. First, the skew and sweep parameters of two-stage blades of an axial fan are defined. Second, response surface methodology is used to study the relationship between the skew and sweep parameters of two-stage blades and the total pressure and the efficiency of the axial fan. The response surface model that describes the relationship between the skew and sweep of two-stage blades and the total pressure and the efficiency of the axial fan is established. Finally, with the skew and sweep of two-stage blades being design variables and the total pressure and the efficiency being the objectives, a particle swarm optimization algorithm is developed to solve this complex multiobjective optimization problem. The optimal result shows that the total pressure increases by 49.1 Pa and the efficiency increases by 1.55%. In addition, the aerodynamic performance of the axial fan is improved. This research has significance to optimization design of the axial fan. Wen-hui Yue, Yong-ping Jin, and Ze-jun Wen Copyright © 2013 Wen-hui Yue et al. All rights reserved.