In this study, the effect of geometrical parameters of Rectangular vortex extrusion die, including twist angle (𝜑 ), reduction in area (𝑅 𝐴 ), and twist zone length (𝐿 ), on deformation inhomogeneity is investigated using the finite element analysis and response surface methodology. Analysis of variance (ANOVA) was used to determine the primary parameters and accuracy of the mathematical model obtained from response surface methodology results. The results showed that the suggested mathematical model predicts the strain inhomogeneity with high accuracy. Additionally, it revealed that the input parameters of 𝜑 , 𝑅 𝐴 , 𝐿 , the interaction between 𝜑 and 𝑅 𝐴 (𝜑 × 𝑅 𝐴 ), and interaction between 𝑅 𝐴 and 𝐿 (𝑅 𝐴 × 𝐿 ) are the main significant factors affecting the inhomogeneity. Perturbation plots and 3D surface diagrams were used to check the results of ANOVA, the sign, and the magnitude of the coefficient of the suggested mathematical model.

vortex extrusion (VE) is a severe plastic deformation technique which is based on the synergies between high strain accumulation and high hydrostatic pressure. Such a high amount of pressure places a mandate to seek the method for investigation of the load under processing conditions. For this, kinematically admissible velocity field and upper bound terms based on Bezier formulation are developed in order to investigate relative pressure in the VE process. Effects of reduction in area, relative length, twist angle, and friction factor in power dissipation terms are systematically analyzed. It is demonstrated that the increase in twist angle, area reduction and friction factor in the VE process increases the relative pressure, which the rates of these increase vary with twist angle. Moreover, the effect of the relative length is different in various frictional conditions. Results of conventional extrusion (CE) are in good agreement with those found by Avitzur for the effect of slug length and friction factor on the relative extrusion stress.

Rectangular S-duct diffusers are widely used in air-intake system of several military aircrafts. A well-designed diffusing duct should efficiently decelerate the incoming flow, over a wide range of incoming conditions, without the occurrence of stream wise separation. A short duct is desired because of space constraint and aircraft weight consideration, however this results in the formation of a secondary flow to the fluid within the boundary layer. The axial development of these secondary flows, in the form of counter rotating vortices at the duct exit is responsible for flow non-uniformity and flow separation at the engine face. Investigation on S-shaped diffusers reveals that the flow at the exit plane of diffusers is not uniform and hence offers an uneven impact loading to the downstream components of diffuser. Experiments are conducted with an S-shaped diffuser of Rectangular cross-section at Re=1.34´105 to find out the effects of the corners (i.e. sharp 90o, 45o chamfered etc.) on its exit flow pattern. A ‘fishtail’ shaped submerged vortex generators (VG) are designed and introduced at different locations inside the diffusers in multiple numbers to control the secondary flow, thereby improving the exit flow pattern. It is found that the locations of the VG have a better influence on the flow pattern rather than the number of the VG used. The best combination examined in this study is a 45o chamfered duct with 3´3 VG fixed at the top and bottom of the duct inflexion plane.The results exhibit a marked improvement in the performance of S-duct diffusers. Coefficient of static pressure recovery (CSP) and coefficient of total pressure loss (CTL) for the best configuration are reported as 48.57% and 3.54% respectively. With the best configuration of VG, the distortion coefficient (DC60) is also reduced from 0.168 (in case of bare duct) to 0.141.

The effect of geometrical parameters involved in vortex extrusion (VE) die design, on AA1050 aluminium alloy processed by VE were investigated using finite element analysis (FEA) and response surface methodology (RSM). For this, VE die length (L), reduction in area (RA), twist angle (𝜑 ), and position of control points in Beziers' formulation (C1) were considered as input parameters and strain inhomogeneity was considered as a response. Both standard deviation (S. D) and inhomogeneity index (Ci) were used to quantify the strain inhomogeneity from FEA results. Analysis of variance (ANOVA) was used to determine the significant parameters and to mathematically model the strain inhomogeneity. It was concluded that standard deviation (S. D) is not a good choice for examining the strain inhomogeneity distribution in VE technique. ANOVA results showed that 𝜑 , RA, and interaction between 𝜑 and RA are the most significant parameters affecting the strain inhomogeneity.

The aim of the present study is to determine the feasibility of making a Rectangular twist waveguide used to rotate electromagnetic waves. For this purpose, the process of fabricating an aluminum Rectangular twist waveguide was simulated by making use of finite element method and Deform software. The optimum length and angle of the twist die for manufacturing a twist waveguide with inner cross sectional dimensions of 22. 86 mm × 10. 16 mm and a length of 50 mm and twisting angle of 90 degrees were investigated. Moreover, the effect of certain factors such as the length, thickness, cross section dimensions of the waveguide and friction on the optimum length of the twist die and cross sectional distortion was studied. The results of this study indicated that the length of the twist die had an influence on the amount of twisting, while friction was of no importance. In addition, comparing the values of effective stress and flow stress at the cross section of the workpiece behind the twist die depicted that the workpiece would not yield behind the twist die due to smaller values of effective stress.