Showing 4 results for Experimental Results
Mohsen Behnia, Mahdi Nili Ahmadabadi, Mohsen Saghafian,
Volume 13, Issue 14 (3-2014)
Abstract
In this study, the radial flow turbine of a cooling turbine is investigated numerically and then compared with the experimental results at some operation conditions. Performance characteristics of the compressor are obtained experimentally by measurements of rotor speed and flow parameters. In this investigation, the turbine performance curve is obtained and three dimensional flow field in the turbine is analyzed. The rotor and casting geometry are modeled in BLADE GEN and CATIA softwares respectively. The TURBO GRID software is used for grid generation of rotor while the ANSYS MESH software is applied for grid generation of casting. Finally, 3D numerical solution of fluid flow in the turbine is solved by CFX flow solver. In this approach, compressible flow equations are solved according to the pressure based method with SST turbulence model. To ensure the numerical results, the grid independency is studied. Finally, the performance characteristics of the turbine are obtained numerically which are then compared to the experimental results. The comparison shows good agreement between numerical and experimental results.
Farid Vakil-Tahami, Ali Ziaei Asl, Peyman Majnoun,
Volume 16, Issue 4 (6-2016)
Abstract
In this paper, experimental data have been used to develop a semi empirical relationship for double-ellipsoidal heat source to model the welding process of a T-shape fillet weld of carbon steel AISI 1020 and stainless steel 304. This model is used in a finite element based computer code to simulate the three dimensional welding process and obtain the temperature profile around the weldment. Experimental data in the form of temperature for certain points have been recorded during the welding process using a computerized data processing system which has been designed for this purpose. Also, the thickness of the weldment layers has been compared by observing their hardness and crystallography. By comparing experimental data with numerical result, the coefficient of the model has been determined using “model updating” process. The effects of material properties and welding parameters have been studied to insure the generality of the model. This model can be used to evaluate the quality of the welding and thickness of the heat affected zone as well as the risks during the welding process such as burn-through and hot cracking. The main advantage of this model is that the number of coefficients is reduced to only one parameter and the rest have been related to the physical and geometrical characteristics of the weld. Results of the numerical simulation obtained using this model show that the major factors which affect the temperature distribution around the weldment are material conductivity, plate thickness, input heating and welding speed.
N. Sepehry, M. Ehsani, M. Shamshirsaz, M. Sadighi,
Volume 20, Issue 7 (6-2020)
Abstract
Employing nonlinear dynamic signature of the host structure for early damage detection and remaining useful life estimation purposes, is an emerging idea in the area of piezoelectric patches based structural health monitoring. Clamped support loosening is one of the defects that not only may cause disorder in system’s functioning, but also obstruct damage identification process through distorting the signals. In this study, support loosening induced contact acoustic nonlinearity (CAN) behavior was monitored by vibro-acoustic modulation (VAM) technique. Using miniaturized PZT patches with the capability to be installed on the host structure permanently for both pump and probe actuation as well as sensing the modulated signal, enabled online monitoring via VAM technique. An appropriate filter was designed to eliminate the unintentionally excited natural frequencies and to reveal the sidebands. In this study, the sensitivity of modulation strength to the pump excitation frequency was also investigated. According to the results, appearance of sidebands around the central probe frequency is an appropriate indicator for CAN identification. In order to study the mechanism of modulation phenomenon, a coupled field electromechanical finite element (FE) model was developed. Proper matching of the numerical and experimental results indicates sufficient accuracy of the developed FE model and its potential to predict the modulation behavior.
Seyyed Amir Ahmadian, Moein Taheri, Mehdi Modabberifar, Ali Jabbari,
Volume 21, Issue 7 (7-2021)
Abstract
Deep drawing is one of the sheet forming processes, in which a metal sheet with mechanical operation, reaches the desired shape. One of the most important issues in deep drawing is the optimal design of the initial blank. In this paper, the main purpose is to design the optimal initial blank (with minimum circumference and minimum defects), for deep drawing of parts with a rectangular cross section. To this end, in this study, a program in Visual Basic has been written in SolidWorks software, in which a rectangular piece and press velocity variables take the tensile depth as input and design the optimal blank. Also in this program, blanks with rectangular, circular, octagonal and rhombus contours have been obtained; So that they are tangent to the initial contour. A separate program has also been written to display contour blanks at different times. The blank design program obtained in this study has this unique feature that for any type of rectangular piece and with any desired dimensions, according to the dimensions of the piece and the depth of tension, it will be possible to design the optimal blank. To ensure the accuracy of the program written in Visual Basic language, the results of the program have been compared and validated by performing experimental work. Experimental results prove that the blanks obtained by the program are of acceptable accuracy. In experimental parts, defects such as earring and shrinkage have also been observed in parts produced with optimal blanks.
