@article{ author = {}, title = {Design and Manufacturing of a Mechanical Device for Dimensional Control of the Airfoil of Turbine Blades}, abstract ={Blade is a sensitive and important part of turbines, and a few companies can produce it. Airfoil of blade has three-dimensional surfaces; therefore, it is necessary to have specific equipment for dimensional control of it. The purpose of this project is to design and manufacture a mechanical system for dimensional control of the airfoil. The foregoing device can produce two-dimensional contours of airfoil on the screen of the profile projector using fine pins. In the mentioned system, the blade is located on the table of device and two sets of pins approach it. In this situation pins are moved forward along their axis until their tips touch the surface of the blade, therefore the tips of pins, shape the contour of the airfoil. Then two sets of pins get away from each other and are moved to the focal area of lens of profile projector via a precision linear system. Then two sets of pins approach each other and reshape the previous contour again. In this situation, tips of pins are projected and contour of airfoil is made on the screen of the profile projector with a predefined scale. Produced contours can be compared with reference ones that have been printed on transparent sheets.}, Keywords = {Turbine Blade,Airfoil,Dimensional Control,Profile Projector}, volume = {7}, Number = {1}, pages = {1-11}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-6788-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-6788-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2008} } @article{ author = {}, title = {Effects of Adaptive Temperature Metal Panels on Thermal Comfort and Energy Consumption of Radiant Ceiling Cooling Systems}, abstract ={Internal thermal conditions and cooling load of the buildings intensely depend on outdoor conditions. Outdoor conditions of the building are not constant during a day, so assumption of constant thermal conditions for indoor is not proper. It seems that using adaptive temperature panels proportional to the variations of outdoor conditions decreases the energy consumption in comparison with constant temperature cooling panels. In this paper the effects of adaptive temperature metal panels are investigated on energy consumption of the buildings and thermal comfort conditions of the occupants. Results of hourly analysis show that, in Tehran with maximum relative humidity of 65%, in buildings with north and south orientations, we do not need cooling systems in nearly 10 hours of a day, in remains we can provide thermal comfort conditions by radiant ceiling cooling panels with natural ventilation and without any anxiety about condensation on the panels. However, in buildings with east or west orientations we do not need to air conditioning and cooling systems in only 7 hours of a day. In these buildings condensation is inevitable in some intervals of system operation during a day. In these periods, we can decrease the probability of condensation by using mechanical ventilation. Results also demonstrate that cooling energy consumption is decreased of 29 to 45% depending on the orientation of building.}, Keywords = {Ceiling Cooling,Radiation,Adaptive Temperature,Energy Consumption,Thermal Comfort.}, volume = {7}, Number = {1}, pages = {13-21}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-7983-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-7983-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2008} } @article{ author = {}, title = {Stress Analysis and Life Assessment of Spot Weld Joints}, abstract ={In this paper, we report results of stress analysis and fatigue life assessment of a number of spot weld joints. Models are presented for corrugated plates, jointed to an L-shape plate using 7 and 14 spot welds, which are subject to four different types of alternating loading conditions. The analyses are based on the solutions obtained from the ANSYS7 finite element package, using solid elements. In this study, strains and stresses in the weld nugget are evaluated. However, the primary focus is on strain-based fatigue life assessment which considers the 3D state of stress around the weld nugget and the nonlinear effects of the materical and the geometry.}, Keywords = {Fatigue,Finite Element Analysis,Strain Analysis,Stress Analysis,Spot Weld.}, volume = {7}, Number = {1}, pages = {23-32}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-6252-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-6252-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2008} } @article{ author = {}, title = {A Comparison Between the Ablation, Thermal and Micro-Structural Properties of Resole Matrix Composites Reinforced with Various Reinforcements}, abstract ={The effect of various reinforcements on the ablative composites has been discussed in this paper. The ability of phenolic resin to reside a char layer at high temperatures is the main reason to select it as a matrix. Analysis of the physical ablation process of a composite and low thermal conductivity of zirconium oxide is performed to produce Resole/carbon fabrics composites coated with a thin film of zirconium at the back side of the specimens. Different materials, such as carbon fabrics, glass fabrics, and also silica and zirconium powders have been used as reinforcements for synthesis of the composites. The specimens were prepared with three sets of compositions. The first set was produced with 37.5 wt% of Resole and 62.5 wt% of reinforcements. Another set of specimens were produced with 40wt% Resole, 40 wt% of silica and 20 wt% of zirconium. To explore the ablation characteristics of the composites in terms of insulation index, erosion rate and microscopic pattern of ablation, an oxyacetylene torch flame with heat flux of 8.35 Mw/m2 at approximately 3000°C was used. It was found from ablation test that the erosion rates of the Resole/carbon fabric specimens are 20% lower than that of the other specimens. Additionally the high insulation index of the Resole/carbon fabrics coated with zirconium, indicates that these composites are the best ablative materials in the present study. SEM observations show that the thermo mechanical and thermo physical erosion effects are the most important factors that influence the ablation process. The proper adhesion between reinforcements and matrix is important to achieve improved ablative properties.}, Keywords = {Ablation,Resol Matrix Composites,Carbon Fabrics,Zirconium,SEM.}, volume = {7}, Number = {1}, pages = {33-44}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-10730-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-10730-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2008} } @article{ author = {}, title = {Augmentation of Heat Transfer During Flow Boiling of R-134a Inside a Tube by Coiled Wire Insert}, abstract ={In the present work, investigation on flow boiling heat transfer of R-134a inside a horizontal tube and also the tubes with coiled wire inserts has been done experimentally. The experimental setup which was used in this investigation was a well instrumented vapor compression refrigeration system. This set-up consists a test evaporator which all the experiments were carried out on it. Refrigerant which flows inside the tube of test evaporator is electrically heated by the coils around it. The evaporator tube is a copper tube with 7.5 mm internal diameter. The range of some operating parameters are: refrigerant mass velocities 54-136 kg/m2s, vapor qualities 0.2-1.0 and heat fluxes 2-6 kW/m2. The empirical data were collected for plain tube and tubes with seven different coiled wire inserts (different coil pitches and different wire diameters). The results show that the insertion of a helically coiled wire inside the evaporator tube increases the heat transfer coefficient by as much as 83% above the plain tube values on a nominal area basis. An empirical correlation was developed to predict the heat transfer coefficient during flow boiling of R-134a inside horizontal coiled wire inserted tubes.}, Keywords = {Heat Transfer Enhancement,Boiling,Evaporator,R-134a,Spiral Spring.}, volume = {7}, Number = {1}, pages = {45-59}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-8743-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-8743-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2008} } @article{ author = {}, title = {Parameters Affecting Hydroforming Deep Drawing and Comparison of ommon Deep Drawing Methods using FEM}, abstract ={In this paper comparison of finite element results and experimental observations of the hydroforming deep drawing is considered in which fluid pressure is used instead of die. Effects of hydroforming parameters during the process are studied, and a comparison with conventional method in deep drawing of aluminum alloys sheets with different blank diameters is presented. Large strain effects, anisotropic material properties, and the Coulomb friction theory in contact surfaces have been considered. ABAQUS code was used for simulation of process. In the first step, the numerical results have been verified by available experimental results, which showed a good agreement. These results contain force-punch travel and thickness strain. In the next step, the effects of initial pressure, friction, and punch radius on wrinkling, tearing, earring, and thickness strain have been studied. The results showed the range of pressure container for the hydroforming deep drawing. A comparison between some of the common deep drawing methods has been presented based on two main failure criteria and thickness strain criteria. Finally it is concluded that the hydroforming process is a more efficient method for achieving the higher drawing rate with respect to the conventional methods.}, Keywords = {Finite Element Method,wrinkling,Earring,Failure Criteria,Thickness Strain Criteria.}, volume = {7}, Number = {1}, pages = {61-69}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-5715-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-5715-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2008} } @article{ author = {}, title = {Measuring Flatness of a Rough Surface using a Capacitor Probe}, abstract ={Measuring topography and flatness of nontransparent rough surfaces using a laser interferometer topography measuring (Zygo) machine is impossible. Due to high accuracy and short measuring time, capacitor probe is a good candidate for measuring topography and flatness of a rough surface. Measuring by a capacitor probe is an average area measuring method and it is suitable for measurment of machinment processes such as ion or blast figure correction, computer control polishing (CCP) and magnetorheological finishing (MRF) methods. The idea of a rough surface which directly can be used for corrective figuring is generated by measuring flatness and waviness of it through a capacitive probe. Among the area averaging methods, the surface capacitance method can be used to elaborate the idea of corrective figuring of a rough surface. Measuring flatness of a rough surface whose roughness (Ra) is in the range of out of flatness is another technical property of the presented method.}, Keywords = {Surface Metrology,Capacitance Measurement,Figure Correcting,Precision Machining.}, volume = {7}, Number = {1}, pages = {71-82}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-5117-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-5117-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2008} } @article{ author = {}, title = {Experimental Investigation of Crack Initiation and Fatigue Life of Spot Weld Coach Peel Specimens}, abstract ={In this paper, an experimental investigation of fatigue crack growth behavior and fatigue life of Coach Peel (CP) specimens is reported. In this investigation, the CP specimens with 1 and 1.5 mm thickness and from mild steel are used. Specimens are tested by a 25 kN capacity INSTRON 8802 servo-hydraulic fatigue test machine under constant amplitude but various level loadings. During loading, the crack length and cycle numbers are measured accurately by a 100X light microscope. Initiation and propagation of spot weld specimens are measured by drawing vertical displacement of the specimen’s vs cycle’s curves. Results show that initiation and propagation of cracks often occur in the plate with less thickness. Also in low level loadings, cracks propagate longtitudinaly, but in high level loadings, usually nugget pull out and joints, fail catastrophically. The crack lengths during propagation, are nearly unique in both plates with the same thickness.}, Keywords = {Spot Weld,Nugget,Crack,Fatigue Life,Crack Initiation,Coach Peel Specimen.}, volume = {7}, Number = {1}, pages = {83-93}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-2179-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-2179-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2008} } @article{ author = {}, title = {Parametric Design and Manufacturing of Precision Forging Dies of Idler Gear of PEUGEOT 405 using CAD/CAM}, abstract ={Design and manufacturing of spur idler gears of gearbox by means of traditional methods, involves too many times of trial and error and consequently spending too much time and money. Utilizing new technologies such as CAD/CAM will increase productivity and flexibility of the process (PDP). In this paper, different parameters and characteristics of the parametric design process of the spure idler gear using CAD/CAM have been discussed and a method for parametric design has been presented. Using this method, design of parts of the same group can be done within the shortest time and by inputing parameters for any part, a typical design can be achieved. Due to the comlex contours and high accuracy requirements of the gear theeth, gear manufacturing is highly specialized, demanding much machining time and therefore is costly. Material wastage is also another problem in these process. In recent years, there has been increased interest in the production of gears by precision forging. Precision forging enables gear teeth to be manufactured to net or near-net tolerances. Resulting in significant savings in raw material and production time compared with conventional cutting methods. In contrast, precision gear forging is associated with problems related to die design, preform volume and geometry, tooth dimensional accuracy, load and energy prediction, ejection problem and finally tool life. These are also reviewed in this paper. Finally, designed dies for manufacturing a typical spur idler gear, analysed by “Super Forge” software.}, Keywords = {CAD/CAM,Parametric Design,Precision Forging,Idler Gear.}, volume = {7}, Number = {1}, pages = {95-107}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-6808-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-6808-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2008} } @article{ author = {}, title = {}, abstract ={}, Keywords = {}, volume = {7}, Number = {1}, pages = {109-118}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-5355-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-5355-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2008} } @article{ author = {}, title = {}, abstract ={}, Keywords = {}, volume = {7}, Number = {1}, pages = {119-130}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-2899-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-2899-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2008} }