Showing 5 results for Optimization
Dr H. Mostan, Dr M. Shamanian, Dr M. Safari,
Volume 1, Issue 1 (1-2016)
Abstract
FeCo-V alloys are one of the most important groups of magnetic material which currently used in high speed engines due to their excellent magnetic and mechanical properties. Welding of these alloys is a great challenge since various phase transformation result in significant changes in magnetic and mechanical properties. In this research ultra-thin FeCo-V magnetic foils were welded using laser and electron beam welding processes. After development of mathematical models, working limits of process parameters were chosen to obtain welded joints which have simultaneously appropriate maximum energy product and mechanical strength.
M. Safari, H. Mostaan, A. Bakhtiari,
Volume 2, Issue 1 (8-2016)
Abstract
In this research, lap joint frictionstir welding of IF sheets with thickness of 0.7 mm is investigated. For this purpose, mechanical properties of joints and also microstructural evolutions are studied. It was found that increase in tool rotational speed and decrease in travel speed results in increase in fracture stress of welded joints. Texture study indicates that no changes can be observed in texture components after friction stir welding. This phenomenon in texture components can be related to high stacking fault energy of IF steel and consequently severe dynamic recrystallization during welding. The results show with increase in the tool rotational speed between 900-1400 Rev/min, ultimate force of fracture of friction stir welded joints is increased. Also, it is concluded from results that with increase in tool travel speed between 50-160 mm/min, ultimate force of fracture of welded joints is decreased. Finally it is proved from results of this paper that in the frictionstir welding of IF sheets with thickness of 0.7 mm, maximum force of fracture of welded joints is achieved in rotational speed of 1400 Rev/min and travel speed of 105 mm/min.
Mehdi Safari, Amir Hossein Rabiee, Jalal Joudaki,
Volume 7, Issue 1 (8-2021)
Abstract
Resistance Spot Welding (RSW) is one of the effective manufacturing processes used widely for joining sheet metals. Prediction of weld strength of welded samples has great importance in manufacturing and different methods are used by researchers to find the fracture force. In this article, the Adaptive Neuro-Fuzzy Inference System (ANFIS) is utilized for prediction of joint strength in welded samples by RSW. A design of experiments (DOE) is prepared according to effective process parameters includes welding current, welding cycle, cooling cycle and electrode force. The sheet metal samples prepared from AISI 1075 carbon steel. Tensile test specimens are prepared and the tensile-shear strength of welded samples are measured. A model is developed according to ANFIS and trained according to teaching-learning based optimization algorithm. 70 % of test data used for network train and the remained 30 % used for access the accuracy of trained network. The accuracy of the trained network was assessed and the results show that the trained network can predict the joint strength with high accuracy. The determination factor (R2) and mean absolute percentage error (MAPE) are 0.99 and 0.48 % for trained data and 0.95 and 6.2% for test data.
Dr. Mohammad Yousefieh,
Volume 7, Issue 1 (8-2021)
Abstract
In this paper, using the Taguchi method, the parameters affecting the toughness of super duplex stainless steels in friction stir welding were optimized. In order to achieve optimal conditions, maximum toughness, the quality characteristic was used as the higher the better. Analysis of Taguchi results showed that in order to achieve optimal conditions in super duplex stainless steel weldments must have a tool rotational speed of 500 rpm, a welding speed of 60 mm / min, an initial pressure of 70 MPa and a tool tilt angle with the workpiece is equal to 3 degrees. Under optimal conditions, the toughness obtained from the confirmation test was 61 J, which was very close to the predicted toughness (58 J). Analysis of variance was also performed on the results of signal to noise (S/N) ratio. According to the results of analysis of variance, the tool rotational speed parameter with an influence percentage of 64% was the most effective parameter on toughness in friction stir welding of super duplex stainless steels. On the other hand, the parameters of welding speed (with an influence percentage of 17 %), initial 2 pressure (with an influence percentage of 16%) and tool tilt angle to the workpiece (with an influence percentage of 3%) were in the next ranks. Also, SEM micrographs from fracture surface of the samples in the impact test proved that the sample that had the least toughness in the impact test had a cleavage morphology and as a result, brittle fracture. This was while the morphology of the fracture surface of the tested sample under optimal conditions (with the highest toughness in this study = 61 J) had a large amount of fine and deep dimples. The presence of these dimples in large quantities indicated ductile fracture and eventually reaching the highest toughness.
M. Niazi, A. Afsari, Seyed A. Behgozin, M. R. Nazemosadat,
Volume 9, Issue 1 (5-2023)
Abstract
Optimization of Stir Friction Welding parameters such as linear and rotational speed of the tool can be effective to a large extent in improving welding properties. In this research, welding of two sheets of Aluminum of Al-7075 and Al-6061 were validated based on theoretical relations and numerical simulation. The simulation of the contact characteristics of the workpieces with the tool was done using the contact algorithms available in the Ansys software. From the FEM, rotational and linear speed and diameter of the tool were selected as design variables, and multi object optimization was carried out with genetic algorithm and RSM to reach the lowest tool temperature and residual stress.The parametric analysis of FSW of the threaded and non-threaded tool pins showed that the generated heat has proportional and inverse relation with rotation and linear speed of tool respectively. Tool with a diameter of 20 mm showed minimum residual stress in the workpiece. By increasing welding speed, the temperature curves become more compact and the effect of thread on heat generation was more evident in all cases at lower heat input.
