Paper Title, Authors, Abstract (Issue 1, Volume 4, 2010)

Pages

Numerical Investigation of Heat Transfer Process Form with Constant Heat Flux in Exothermic Board by Natural Convection Inside a Closed Cavity
Behnaz Arjoman Kermani

Abstract: Natural Convection process within a closed cavity when heat source is on the vertical wall of it special importance .heat source generate constant heat flux. A common practical example of this case is electronic boards inside a computer or radiator in the room. One of the important parameters in designing electronic boards in the computer or another things is the maximum temperature of pieces; therefore we must examine the factors that affect this to have a reduced the maximum temperature. Governing equations on fluid flow mass, velocity and energy equations using the finite element method with power law, pr = 0.7, a non-uniform network is converted to algebraic form. Because of buoyancy force the Momentum equation depended on temperature. Momentum equations and energy equation are solved simultaneously. Momentum equations that include unknown pressure solve with Simple algorithm. The velocities are obtained from Momentum equation must satisfy continuity equation. Heat generation is constant. Wall’s temperature is T? (temperature of environment). At first velocity of fluid is . With these boundary conditions we check the effect of thermal springs placed inside the cavity, cavity dimensional, size of thermal springs (heat source) to reduce temperature. Convergence of the energy equation is 10-7. Convergence standard is temperature changes.
 

The Analysis of the Transient Dynamic Response of Elastic Thin-Walled Beams of Open Section via the Ray Method
Yury A. Rossikhin, Marina V. Shitikova

Abstract: The problem on the normal impact of an elastic rod with a rounded end upon an elastic Timoshenko arbitrary cross section thin-walled beam of open section is considered. The process of impact is accompanied by the dynamic flexure and torsion of the beam, resulting in the propagation of plane flexural-warping and torsional-shear waves of strong discontinuity along the beam axis. Behind the wave fronts upto the boundaries of the contact region, the solution is constructed in terms of one-term ray expansions. During the impact the rod moves under the action of the contact force which is determined due to the Hertz’s theory, while the contact region moves under the attraction of the contact force, as well as the twisting and bendingtorsional moments and transverse forces, which are applied to the lateral surfaces of the contact region. The procedure proposed allows one to obtain rather simple relationship for estimating the maximal magnitude of the contact force, which can be very useful in engineering applications.
 

    Paper Title, Authors, Abstract (Issue 2, Volume 4, 2010)

Pages

Experimental Results Analysis for UiTM BWB Baseline-I and Baseline-II UAV Running at 0.1 Mach Number
Wirachman Wisnoe, Wahyu Kuntjoro, Firdaus Mohamad, Rizal Effendy Mohd Nasir, Nor F Reduan, Zurriati Ali

Abstract: This paper presents results analysis for two models of UiTM Blended Wing Body (BWB) UAV tested in UiTM Low Speed Wind Tunnel. The first model is known as the BWB Baseline-I and the new model known as BWB Baseline-II. The Baseline-II has a simpler planform, broader-chord wing and slimmer body compared to its predecessor while maintaining wingspan. The wind-tunnel experiments were executed at around 0.1 Mach number or about 35m/s with 1/6 scaled down model. Baseline-I is designed with centre elevator while Baseline-II uses canard for pitching motion purpose. The experiments were carried out at various elevator and canard deflection angles. The lift coefficient, drag coefficient, pitching moment coefficient, L/D ratio and drag polar curves were plotted to show the performance of aircraft at various angle of attack. For zero elevator and canard deflection the results show similar trends in terms of lift curve, drag curve and pitching moment curves for both aircrafts.
 

Hydraulic Efficiencies of Impeller and Pump Obtained by Means of Theoretical Calculations and Laboratory Measurements for High Speed Impeller Pump with Open-Flow Impeller with Radial Blades
Andrzej Wilk

Abstract: The article discusses the results of measurements of parameters of a high speed impeller pump with open-flow impeller having radial blades. The method of calculating the hydraulic efficiency of the pump and an impeller was proposed on basis on laboratory measurements. Using the results of measurements of pressure in the space around the open-flow impeller with radial blades the hydraulic efficiency of pump and impeller were calculated.
 

    Paper Title, Authors, Abstract (Issue 3, Volume 4, 2010)

Pages

Processing by P/M Route and Characterization of New Ecological Aluminum Matrix Composites (AMC)
Ileana Nicoleta Popescu, Simona Zamfir, Violeta Florina Anghelina, Carmen Otilia Rusanescu

Abstract: The continuous development of technology in automotive manufacturing process has required new solutions adapted to the growing requirements of lightweight, non-pollution for the environment materials with a low cost production. According with these required characteristics of materials, the aims of this paper were to manufacturing Al-Cu/SiCp composites by powder metallurgy (P/M) processing route and characterization of the powders and compacted/sintered mixture powders. Was developed a complex experimental program consisted in variation of silicon carbide proportion (5-20%wt.) in the composites and also was established the effect of proportion of SiC?s addition on: a) characteristics of powders mixtures Al-Cu/ SiCp; b) press densification of materials at different applied pressure (50-450 MPa); c) the porosity evolution (sintering densification) respectively dimensional variation, the homogeneity and hardness of sintered materials, in the solid state (at 520-548oC) and in the liquid phase (548-620oC). To characterize powders, mixtures of powders and obtained composite materials from physic-mechanical, chemical and technological point of view were used for investigation, classical and also modern techniques, such as: Environmental Scanning Electron Microscopy, Electron Probe Micro Analyzer and X-ray diffraction. Hardness was correlated with physical and microstructural characteristics, thereby determining the sintering temperature and optimum proportion of carbide particles that assure the best densification of materials and the best mechanical characteristics. After investigations was resulted that the best characteristics of composite materials was obtained at a proportion of 10 and 15% wt. SiCp, cold pressed at 450 MPa, dewaxed / presintered between 300 and 400oC, for 30 min (maintenance temperature/ time) and sintered at 620oC/60 min in protective atmosphere.
 

Contributions Above the Dew-Point Problem in Civil Building EPS Insulated Walls Modeling with Finite Element the Convective Heat Transfer
Madalina Xenia Calbureanu, Emil Albota, Dragos Tutunea, Sorin Dumitru, Raluca Malciu, Alexandru Dima

Abstract: In this paper we present the analysis of convective heat transfer in the walls of a house insulated with polystyrene. In the first part we make an evaluation of the insulation that is currently used in the houses. We start the simulation using a real model of a house and than we make the model in Solidworks 2009. We run the model in Solidworks Thermal study after we insert the initial conditions. We notice that the obtained results indicate a problem which occurs inside the brick, the dew-point appearance. Further investigations must be made to solve this problem.
 

Geometry Optimization of Piezoceramic Laser Shutter
G. Kulvietis, I. Tumasoniene, R. Bansevicius, A. Grigoravicius, V. Jurenas, S. Navickaite

Abstract: Usually numerical modeling and simulation of multicomponent piezoelectric actuators lead to the large number of recurred calculations with different geometrical parameters of the actuator. The exchanges in the modal shape sequence are a general case problem concerning to all mechanical structures. This problem is also important for optimization, since calculations are tied both to eigenfrequencies and eigenforms. If the eigenfrequency is chosen incorrectly, the piezoactuator will not function, so it is very important to numerically determine eigenforms. In this paper are overlooked piezoelectric actuators concept and urgency, proposed model of a laser shutter and piezoelectric laser gate, analysis of geometrical parameters optimization is done. What is more, influence of geometrical parameters and advantage of the domination coefficients are presented, calculations, results and conclusions are given.
 

NC Programs used in Reverse Engineering Technique
C. Cioana, D. Stan, C. Cosma, V. Tu

Abstract: The paper presents the use of two techniques Reverse Engineering and Rapid Prototyping on a product, aiming to demonstrate the efficiency on time and cost reduction. We want to underline the need to implement these techniques in design and product manufacturing. We will apply Reverse Engineering on a part which represent a prototype made from a special resin using Stereo Lithography process, and try to obtain the virtual model. Working in the Reverse Engineering domain we propose a path to obtain virtual models from NC programs imported in CAD software. The paper presents a method of modeling a virtual object that can be compared with the technique of Reverse Engineering, meaning that the parametric model will be done using the information received from a NC program. The NC program contains information about the strategies used in making the part, technological parameters (cutting feed, cutting speed), tool type and characteristic and the most important thing in this matter – the tool path. All this information is useful for the operator of the CNC machine in the production stage, but we will use some of them to recreate a virtual model.
 

    Paper Title, Authors, Abstract (Issue 4, Volume 4, 2010)

Pages

Application of CAD/CAM/FEA, Reverse Engineering and Rapid Prototyping in Manufacturing Industry
V. Tut, A. Tulcan, C. Cosma, I. Serban

Abstract: The paper presents some aspects about rapid prototyping which stays at the base of manufacturing design using CAD/CAM/FEA programs, scanning and measuring machining and its integration in industrial field. A big economical advantage is that products made by rapid prototyping express a low risk failure and the manufacturing process takes less time and lower costs than the conventional techniques. A new gasket for a ball screw used in a bending tube machine was produced by rapid prototyping techniques starting from a broken one. First the broken gasket was scanned by Modela Roland LPX-600 scanning machine obtaining the primary 3D model which is imported to CAD/CAM programs and the final product is achieved on ISEL GFM 4433 milling machine..The gasket mechanical characteristics were investigated by finite element analysis (FEA). FEA provides a way of simulating the gasket design under working condition and an opportunity to understand interactions with the mating machine. Therefore, problems in tooling or mold mating would be minimized. After FEA simulation a new material was chosen in order to increase the mechanical characteristics. The new gasket material improves the tool wear and life, scuff resistance, breaking strength and handling characteristic After that the gasket is assembled on the ball screw of the bending tube machine in order to observe its functional behavior.
 

Simulation and Design of Jigs for Bus's Chassis Production
Somsak Siwadamrongpong, Usawadee Ongarjwutichai

Abstract: Bus manufacturing is one of important automobile industries. In small enterprise, bus chassis is based on manually production. The manual production is low production rate and long throughput time. Moreover, the manual processes are also difficult to make standardization and lead to maintenance difficulty. Therefore, this study aims to design production jigs for bus chassis and use finite element method to analyze the jigs. Production rate with various production scenarios also analyzed. 2 models of Chassis technical data and information was collected from bus manufacturer. The chassis was break into sub-assemblies. 4 Jigs were designed for production of all sub-assemblies. Jigs design was built and assembled on SolidWork, finite element method was carried out by using ANSYS Workbench. Simulation results show that the minimum safety of factor occurs with factor 1.94. Re-design of jigs yield an improvement on the weak point with safety of factor 4.20. Standard time for production of each sub-assembly was calculated. It was found that production rate of 2.3-2.8 chassis/day is achieved based on 2-man working with 4 jigs. The 4-man working yields about 75% increasing in production rate with also increase of %idle time compared to 2-man working scenario. 6-man working with additional 2 jigs found that production rate of 5 chassis/day.
 

Numerical and Experimental Optimization of Mechanical Stress, Contact Temperature and Electrical Contact Resistance of Power Automotive Connector
Amine Beloufa

Abstract: One of the major difficulties of the use of power automotive connectors is the increase of their electrical contact resistance in the running time. This paper attempts to fill this gap and discloses the minimisation of the transient electrical contact resistance and contact temperature by the experimental and numerical means. The tested contact samples have the sphere/plane contact shape in order to simulate the real contact in the power automotive connectors and were made with high copper alloys. These contact samples were submitted to high current (100 A) and different contact forces (50 and 100 N). Experimental results showed that the lower transient values of electrical contact resistance and contact temperature correspond to the contact sample made with copper alloy C19210 and which is submitted to the highest contact force (100 N). In order to more minimize the electrical contact resistance of the contact sample made of copper alloy C19210, finite element models were developed with one contact point and with multipoint contacts using a commercial code. Deformation of contact surfaces, numerical transient values of contact resistance and contact temperature were calculated basing to the indirect coupling program which is developed by an APDL language. This program can make the coupling between the mechanical and thermoelectric fields and takes into account the elasto-plastic behaviour of the material C19210 which is identified by tensile tests. Results showed that the sample with multipoint contact presents a transient values of contact resistance and contact temperature lower than the ones obtained with one contact point, also the maximum mechanical Von Mises stress obtained for the model with multipoint contacts is not only lower than the yield stress of the material C19210 but also lower than the one obtained for one contact point. Therefore, the gain for the model with multipoint contacts was triple.
 

Impact-Echo Nondestructive Testing and Evaluation with Hilbert-Huang Transform
Ruichong Zhang, Abdennour C. Seibi

Abstract: This study proposes the implementation of Hilbert-Huang transform (HHT) time-frequency analysis in impact-echo (IE) testing for improved accuracy in integrity appraisal and damage diagnosis of infrastructure systems. In particular, this paper first reviews the fundamental of IE non-destructive testing and evaluation, i.e., formula of thickness estimation which is based on onedimensional wave propagation and dependent upon the selected longitudinal wave speed of the materials under test, resonance frequency identified with fast Fourier transform (FFT) of IE recordings, and a shape-based correction factor. While this study details multiple causes of the distorted thickness estimation with the formula from the mechanics point of view, FFT-based analysis is among the most important factors. A time-frequency HHT analysis is then introduced to overcome the shortage of FFT analysis in identifying the resonant frequency from noise-added IE recordings. With FFT and HHT analyses of five data sets of sample IE recordings from sound and damaged concrete structures and comparison with referenced ones, this study reveals that the proposed IE approach with HHT analysis not only eliminates the subjective use of correction factor in the formula, it also improves greatly the accuracy in the thickness estimation.