Showing 3 results for Azizi Tafti
Yaghoob Dadgar Asl, Mehdi Tajdari, Hassan Moslemi Naeini, Behnam Davoodi, Roohollah Azizi Tafti, Valiollah Panahizadeh Rahimloo,
Volume 15, Issue 7 (9-2015)
Abstract
One of the most important issues in the review of cold roll forming process of metals is estimation of required torque. The optimum production line can be designed by determining the effective parameters on torque. Some of these parameters are sheet material and thickness, bending angle, lubrication conditions, rolls rotational speed and distance of the stands. The aim of this study is to predict amount of required torque considering the factors influencing torque, including thickness, yield strength, sheet width and forming angle using artificial neural network. So the forming process was 3D simulated in a finite element code. Simulation results showed that with increase of yield strength, thickness and forming angle, applied torque on rolls will increase. Also the increase in sheet width -assuming constant web length- will decrease the torque needed for forming. The effects of thickness and sheet width were experimentally investigated which verified the results obtained by finite element analysis. A feed-forward back-propagation neural network was created. The comparison between the experimental results and ANN results showed that the trained network could predict the required torque adequately.
H. Yousefian, H. Moslemi Naeini, R. Azizi Tafti, B. Abbaszadeh,
Volume 18, Issue 9 (12-2018)
Abstract
In this paper, considering the increasing need for high strength and thin pipes in the oil and gas industries, the effects of material strength and the initial thickness of the pipe and the friction between the pipe and the roller, on the distribution of the thickness and ovality of the cross-section of pipe in the process of sizing have been numerically and experimentally investigated. The simulation is performed using the commercial software MSC Marc Mentat. Results of the simulation show that by increasing strength material and reduction of thickness, the ovality of the cross-section of pipe decrease. It has been shown that with a 2.77-fold increase in the yield strength of a pipe with thickness of 2.8 mm, the ovality decreased by 27%. By decreasing the thickness of the St37 pipe from 2.8 to 1.8 mm, the ovality decreased to 2%. These changes increase with increasing yield strength, so that in the alform700 pipe with a thickness reduction of 2.8 to 1.8 mm, the ovality decreased to 45%. Furthermore, the friction condition has very little effect on the ovality of pipe. The validity of the finite element simulation is confirmed by comparison with experimental results.
Mohammad Abbasi Khatoon Abadi, Roohollah Azizi Tafti,
Volume 23, Issue 2 (February 2023)
Abstract
During root canal treatment, whole or a part of the tooth crown may be lost. Post and core is a method of repairing a damaged crown, in which a pinjet dipped in acrylic resin is used to mold the tooth canal and make a cast post and core. The main goal of this research is to produce an inexpensive pinjet with required strength and proper adhesion to acrylic resin. Therefore, to determine a right material for pinjet, lap shear and tensile tests were performed on eight polymer materials to check the adhesion of pinjet to acrylic resin and its yield strength, respectively. To produce some pinjets, a plastic injection mold was built and Moldflow Insight software was used to determine the process parameters of the injection molding. The results showed that HIPS 7240 with the lowest price among the examined materials and sufficient adhesion to acrylic resin is a suitable material for the pinjet. Also, this material with a yield strength of 10.91 MPa had an appropriate strength to prevent plastic deformation during the post and core molding process. While the injection time, melt temperature, and mold temperature were considered to 1 s, 230 ˚C, and 25 ˚C, respectively in both simulation and experimental methods, the injection pressure was 19 and 18 MPa and the injection speed was obtained 0.3 and 0.27 cm/s respectively in the simulation and experiments. Producing a perfect pinjet shows the ability and accuracy of the simulation in proposing the process parameters of plastic injection molding.
