http://ir.bdu.edu.et/handle/123456789/10417 2001-01-13T06:39:26Z http://ir.bdu.edu.et/handle/123456789/16389 Multi-Objective Process Parameter Optimization of TIG Welding on AISI 304 Stainless Steel and AISI 1020 mild steel using Artificial Neural Network with Genetic Algorithm Yegnanesh, Ashagrie Yimer Tungsten inert gas (TIG) welding is a highly significant arc welding process that utilizes a non-consumable tungsten electrode and an inert gas for arc shielding, resulting in excellent weld quality and precise welding operations. In structural applications, dissimilar metal joints, such as those between stainless steel and mild steel, are widely used due to their favorable mechanical properties. However, joining these materials presents challenges related to differences in composition, thermal properties, mechanical properties, and the formation of intermetallic compounds (IMCs) at the joint interface. This study focused on optimizing TIG welding parameters (i.e. welding current, arc voltage, welding speed, and gas flow rate) for joining AISI 1020 mild steel and 304 stainless steel 2mm thickness sheet metals. The developed automated TIG welding fixture improves weld quality by maintaining constant welding speed, minimizing defects associated with fluctuations in human-operated torch movement. The automated TIG welding fixture can be used to weld sheet metal in a single pass by linear motion. Three levels of variation were applied to the selected input parameters, and nine experiments were carried out using Taguchi's L9 orthogonal array approach. An Artificial Neural Network (ANN) was constructed to model the automated sheet metal TIG welding process, with a 4-10-3 network trained by the Levenberg-Marquardt algorithm mean squared error (MSE) of 1.0069e-1. The objective was to increase the hardness, tensile strength, and bending strength of the weld quality. The Multi-Objective Genetic algorithm (MOGA) was used to determine the combination of optimal process parameters, which was identified as welding current 91.835 A, welding voltage 13.856 V, welding speed 19.850 cm/min, and gas flow rate 5.388 L/min resulting in maximum achieved values of Ultimate tensile strength 539.516 MPa, Rockwell hardness 92.449 HRB, and bending strength 731.216 MPa. Finally, a confirmation test was conducted with the optimum parameters. The predicted and confirmation test results percentage error was 0.23 % for tensile strength, 0.82 % for hardness, and 0.18% for bending. Thus, it has been concluded that the confirmation experimental results are within the acceptable range of percentage error as per the reviewed literature. Keywords: Dissimilar metal joints,TIG Welding process parameters, Artificial Neural Network (ANN), Multi-Objective Genetic Algorithm (MOGA), mechanical properties. 2024-02-01T00:00:00Z http://ir.bdu.edu.et/handle/123456789/16388 PARAMETRIC OPTIMIZATION OF TUNGSTEN INERT GAS WELDING FOR ALUMINUM 1100 BY USING RESPONSE SURFACE METHODOLOGY WEGAYEHU, MULUNEH ZELEKE This research presents the results of tungsten inert gas (TIG) welding of aluminum alloy 1100 in the butt joint, with single pass. The sample dimensions were 100 × 50 × 3mm3. The TIG welding was done with 2.4 mm diameter filler of ER4043. Tensile and hardness tests were performed on successfully welded samples to determine the best welding parameters. In this work, a quadratic response surface model is fitted to the obtained data, using response surface methodology (RSM) to identify and analyze the interactions between the responses of controllable factors and to optimize process parameters. The main factors influencing the choice of welding are the range of the material to be welded, which is aluminum alloys, the thickness of the base materials, and the type of parameters. TIG welding is a simple and user-friendly welding procedure. This study takes into account the frequently used aluminum AA1100 alloy in order to optimize the process parameters. By taking into account the key influencing process parameters such as welding current, root gap, and gas flow rate with 18 experimental runs and 5 levels, the response surface methodology with central composite design as the design of experiment was used. The results were analyzed using design expert statistical software. The analysis was performed using these parameters, and the responses, tensile strength and hardness, were obtained to provide the best results. The experiment shows that the desirable parameter among the solutions was attained, with the best values being current of 118.44 Amp, root gap of 1 mm, and gas flow rate of 8 L/min, with a desirability of 0.879. These parameters can be used to achieve better hardness and tensile properties of the welded metal. Keywords: RSM, Central composite design, Aluminum1100, TIG welding parameters, Alternative current, parametric optimization, Mechanical properties, 2024-03-01T00:00:00Z http://ir.bdu.edu.et/handle/123456789/16386 NUMERICAL AND EXPERIMENTAL STUDY ON THE PERFORMANCE OF SOLAR PHOTOVOLTAIC PANELS BY COOLING MECHANISMS USING FINS AND PHASE CHANGE MATERIALS. KASSA, ENAWGAW Due to increased efforts to reduce carbon emissions and ensure sustainable growth of the energy supply, the use of solar energy for electric power generation through photovoltaic (PV) cells has experienced outstanding growth in recent years. However, low conversion efficiency has been a significant problem for PV system applications. According to previous studies, the conversion efficiency of the PV panel decreases at high temperatures. Therefore, a variety of cooling techniques have been carried out to make PV cells more efficient by avoiding the issue of temperature rise, using active and passive cooling techniques. However, active cooling system needs extra electrical energy for pumping and spraying water, and the system becomes more complex. To avoid system complexity due to active cooling systems, researchers used passive cooling systems such as PCMs, fins, composite PCMs, enhanced PCMs, and heat pipes. Although a PV-PCM+Fins system has been investigated by many researchers, it still requires more study, particularly with respect to the melting temperature of PCM and the placement of fins and PCM. In this paper, four organic PCMs (PV-PCM), such as PV-RT28, PV-RT35, PV-RT44, PV-PT58, and fins are investigated numerically without varying the mass of the PCM. Transient numerical simulations have been carried out with Ansys Fluent software using a 2-D simplified geometry. The simulated results of the model have been validated experimentally with PV-PT58/fins configured externally. Results from the numerical observation show that the temperature of the PV panel with RT28, RT35, and RT44 was maintained below the reference panel temperature for only 1 hour, 2 hours, and 3 hours, respectively. However, after 1 hour, 2 hours, and 3 hours with respect to each model, the temperature of the cooled panel was higher than the reference panel due to the fact that the PCM was completely melted. The temperature of the panel, however, was maintained close to the ambient temperature using PT58 and PT58/fins configured both internally and externally for the whole day. The experimental findings show that the cooled PV module had an average efficiency of 12.03% compared to the uncooled panel's 10.84%. Keywords: Numerical Study, Experimental Study, Photovoltaic Panel, Externally and Internally configured fins, Phase Change Materials, Efficiency Improvement. 2024-01-01T00:00:00Z http://ir.bdu.edu.et/handle/123456789/16385 Optimization of TIG Process Parameters of Stainless Steel 304L Pipe Welding based on the Mechanical properties. Fantahun, Yemane Tungsten inert gas welding (TIG) is a fusion welding process that has a wide variety of applications in today's industry. The TIG welding parameters play a very important role in evaluating the quality of a weld. This study's primary objective was to optimize the mechanical properties of TIG welding on stainless steel pipe 304L using a various input parameters, such as amperage, travel speed, root gap, and gas flow rate. Experimental methodology with Taguchi based gray relation analysis conducted to optimize the process parameters of TIG welding process on the material 304L stainless steel pipe welded samples of the dimension 16 pieces of ø89mm*125mm*5 mm. ANOVA was conducted in order to examine the significant of welding process parameters using Minitab 19 software were used. The data was collected by observing, photographing and Hardness and tensile experimental tests results. The obtained result improved the mechanical property of the joints with a parameter setting of welding current150 A, travel speed of 1.5 mm/sec, a gas flow rate of 12 lit/min, and a root gap of 2.4 mm, the optimal hardness value of 108.92 HRB was measured, and the optimal tensile strength of 1224MPa was attained using the following parameters: a travel speed of 1.5 mm/sec, a maximum welding current of 150 A, a gas flow rate of 12 liters per minute, and a root gap of 2.4 mm. The ANOVA result shows as Welding current, travel speed and Gas flow rates are the most significant parameters respectively. Keywords: - TIG welding, mechanical properties, Taguchi-Based GRA, weld 2022-09-01T00:00:00Z