Experimental and numerical investigation of double bulge tube hydroforming
M.
Gheisary
Iran University of Science and Technology
author
F.
Djavanroodi
Iran University of Science and Technology
author
text
article
2010
per
This paper aims to establish a basic understanding of double bulge tube hydroforming process of stainless steel deep drawn cups. The method is briefly reviewed by carrying outexperimental tests and Finite element analysis. After measuring bulge height in both formed curves by CMM and thickness variation of formed tube by ultrasonic thickness measurement unit, it’s found out that thickness variation in this process is less that other traditional methods such as traditional spinning and rubber pad forming. A finite element model is constructed to simulate the double bulge tube hydroforming process and asses the influence of friction coefficient and tube material properties. It is found that material hardening coefficient had the most significant influence on formability characteristics during double bulge tube hydroforming. As similar as other tube hydroforming processes, increasing friction decrease bulge height and thickness.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
10
v.
شماره 3 پاییز 1389
no.
2010
1
9
http://mme.modares.ac.ir/article_1385_00dac8449a88fa9b189104c830cf3940.pdf
Direct Numerical Simulation of 2D Forced Jet using the Compact Finite Difference Method
M.J.
Maghrebi
Ferdowsi Uni. of Mashhad
author
H.
Eazi
Shah rood University of Technology
author
A.
Zarghami
Uni. of Tech., Shahrood
author
text
article
2010
per
The dimensionless form of Navier-Stokes equations for two dimensional jet flows are solved using direct numerical simulation. The length scale and the velocity scale of jet flow at the inlet boundary of computational domain are used as two characteristics to define the jet Reynolds number. These two characteristics are jet half-width and centerline velocity. Governing equations are discretized in streamwise and cross stream directions using a sixth order compact finite difference scheme and a mapped compact finite difference method, respectively. Cotangent mapping of is used to relate the physical domain of to the computational domain of . The compact third order Runge-Kutta method is used for time-advancement of the simulation. convective outflow boundary condition is employed to create a non-reflective type boundary condition at the outlet. An inviscid Stuart flow and a completely viscose solutions of Navier Stokes equations are used for the verification of numerical simulations. Results for perturbed jet flow in self-similar coordinates were also investigated which indicate that the time-averaged statistics for velocity, vorticity, turbulence intensities and Reynolds stress distribution tend to collapse on top of each other at flow downstream locations.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
10
v.
شماره 3 پاییز 1389
no.
2010
9
20
http://mme.modares.ac.ir/article_1386_5040db68d3b607236b5644f27e609f7e.pdf
Theoretical Calculation of the Instantaneous Folding Force in a Single-Cell Square Column under
Axial Loading
A.
Niknejad
Tarbiat Modares University
author
G. H.
Liaghat
Tarbiat Modares University
author
H.
Moslemi Naeini
Tarbiat Modares University
author
A. H.
Behravesh
Tarbiat Modares University
author
text
article
2010
per
In this paper, a theoretical formula is derived to predict the instantaneous folding force of a single-cell square column under axial loading. Calculation is based on analys of “Basic Folding Mechanism” introduced by Wierzbicki and Abramowicz to calculate the instantaneous folding force. For this purpose, three mechanisms of energy dissipation were assumed. The formula obtained in this paper, can predicts the instantaneous folding force variations versus folding distance and versus folding angle with good precision and can predict folding force in each time instance instead of the average value. The results of theoretical formula were compared with experimental data and good agreement was observed.
Keywords: Instantaneous Force, Folding, Honeycomb, Square Column.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
10
v.
شماره 3 پاییز 1389
no.
2010
21
30
http://mme.modares.ac.ir/article_1387_fe25f9bef9e5a7dc44849d0dff52608a.pdf
General Solution of Plane Elasticity of Axisymmetric Functionally Graded Thick Cylinderical Shells
G. H.
Rahimi
Tarbiat Modarres Univ
author
M.
Ghannad
Tarbiat Modarres Univ
author
S.
Esmaeilzadeh Khadem
Tarbiat Modarres Univ
author
text
article
2010
per
- In this paper, an analytical formulation of FGM axisymmetric thick-walled cylinders, based on the plane elasticity theory is presented. The stress and displacements in thick cylindrical shell are calculated using the real, double and complex roots of characteristic equation. Solutions are obtained under generalized plane stress, plane strain and closed-ends cylinder assumptions. It is assumed that the material is isotropic and heterogeneous with constant Poissn's ratio and radially varying elastic modulu. The results have been compared with findings of the researcher (2001) [hoop stress is incorrect], and we have present corrected version as well as supplementary findings.
Keywords: Thick-Walled Cylinder, FGM, Plane Elasticity
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
10
v.
شماره 3 پاییز 1389
no.
2010
31
43
http://mme.modares.ac.ir/article_1388_3765e0f08ae5ddaca06f93c0fcca41ea.pdf
Performance Improvement of Ceiling radiant Cooling System by Suitable Design of Panel Height
Q.
Dorosti
Tarbiat Modarres Univ
author
M.
Maerefat
Tarbiat Modarres Univ
author
A.
Omidvar
Univ. of Technology Shiraz
author
text
article
2010
per
- The effect of panel height on performance of ceiling radiant cooling system has been studied. Investigation has been done by employing solution of conservative equations, together with the radiant and thermal comfort equations. Calculation is performed for the typical hottest day of Tehran. Vapour condensation is one of the most important problems whit these systems. Therefore effect of panel height on condensation has been also studied, in a residential place with several different ranges of ventilation rate. The results show that appropriate design of the panel height can significantly reduce the rate of condensation.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
10
v.
شماره 3 پاییز 1389
no.
2010
45
56
http://mme.modares.ac.ir/article_1389_8bb1fa2d68ae514a0d672092521fa5ab.pdf
Evaluation of the Range of Performance for a Probe Consisting of Two Parallel Hot-Film Cylindrical Sensors in Reverse Flows
M. A.
Ardekani
Iranian Organization for Science and Technology (IROST)
author
P.
Asghari Tehrani
Farasanjesh Saba
author
text
article
2010
per
Hot wire Anemometer (CTA) can be used to measure instantaneous flow velocity with high frequency. Since the principle of opearation of CTA is based on convective cooling, determination of the air flow direction is difficult. In this Research paper, we have used two cylindrical hot-film sensors placed in parallel to determine the flow direction. The wake effect and the heat due to the upstream sensor on the downstream sensor has been used to identity the flow direction. Effect of wake and presence of the upstream sensor on the downstream sensor has been studied. The results have been used to construct a probe consisting of two parallel sensors, sepereated by 1mm distance. Performance of the probe has been evaluated at various flow angles for laminar and turbulant flows. Findings of this study show that this probe provides the best performance at ±10 flow angles.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
10
v.
شماره 3 پاییز 1389
no.
2010
57
66
http://mme.modares.ac.ir/article_1390_8f2690b7a6730c7cd71509a6ba0ded8f.pdf
Theoretical and Experimental Study of the Effects of Process Parameters on Bending Angle in Laser Bending process
M.
Hoseinpour Gollo
University of Mohaghegh ardabili
author
H.
Moslemi Naeini
Tarbiat Modares University
author
G.H.
Liaghat
Tarbiat Modares University
author
S.
Jelvani
, Nuclear Science & Technology Research Institute
author
text
article
2010
per
- In this paper an analytical model for prediction of angular deformation is presented. In this model convective heat losses and a multipoint distributed heat source is used for determination of the inherent strain zone which causes the bending angle. The effects of laser bending process parameters including laser power, beam diameter, scan velocity and pulse duration on the bending angle were investigated experimentally. Main effects of factors were considered and the regression line was derived. An L9 Taguchi’s standard orthogonal array was employed as experimental design and the level of importance of the laser bending process parameters on the bending angle was determined using analysis of variance (ANOVA). Comparison of the analytical model and experimental results has shown a reasonable agreement.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
10
v.
شماره 3 پاییز 1389
no.
2010
67
86
http://mme.modares.ac.ir/article_1391_cd429895cfd19188a1d4de809321be4e.pdf
A new Hydro forming Die Design for Improvement of Die Corner Filling of Stepped Tubes
M.
Elyasi
Babol Noshirvani Univ. of Tech
author
M.
Bakhshi-Jooybari
Babol Noshirvani Univ. of Tech
author
A. H.
Gorji
Babol Noshirvani Univ. of Tech
author
text
article
2009
per
Tubular components, such as stepped tubes, conical tubes and box-shape tubes, are mainly produced by tube hydroforming process. Obtaining a sharp corner is the main goal in some of these components. In this paper, corner filling in stepped tubes is studied using a new multistage hydroforming die. The proposed die was simulated and filling of the die cavity was investigated. The finite element software, ABAQUS 6.4, has been used for simulation. In order to verify the simulation results, the new die of stepped tube was manufactured and then experiments have been performed on it. The results of the experiments verified the simulation results. It was shown that by using the new die, parts with sharp corners could be produced. The simplicity of the die and the low internal pressure are among the advantages of this die.Thickness distribution was also examined by FE simulation and via experiments and it is shown that a better distribution could be obtained by the proposed die set.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
10
v.
شماره 3 پاییز 1389
no.
2009
87
98
http://mme.modares.ac.ir/article_1392_d2f31d3004acac2424ee5e4c970a4d7b.pdf