International Journal of Advanced Design and Manufacturing Technology
Volume:3 Issue: 4, Sammer 2010

In this paper, a novel technique on friction aided deep drawing using tapered blank holder divided into eight segments is proposed to overcome defect of friction aided deep drawing using four segments tapered blank holder technique. A taper blank holder is designed to be of two parts: stationary part with 5 degree taper angle and moving parts divided into eight tapered segments. The main function of this tapered blank holder device is adopting the frictional force between the blank and the blank holder segments to work in the useful drawing direction. At first, the drawing mechanism of eight segments tapered blank holder technique and inflow of material in the flange portion of blank are investigated and compared with four segments tapered blank holder technique by ABAQUS software to show the merits of the proposed process. Then, the finite element analysis of springback is investigated by the ABAQUS software. Effect of different process parameters such as initial blank thickness, punch profile radius, blank holder force, friction coefficient and hardening models on springback prediction are studied. A successful deep cup with drawing ratio up to 3.67 can be produced without any defect by using this new technique only in one die set. The cost and time of die fabrication in this technique are less than the conventional deep drawing.

In this paper a performance analysis is presented for a cable-suspended parallel manipulator. Experimental results from some first tests are presented and discussed to validate the theoretical calculation of load carrying capacity. The load-carrying capacity during a given trajectory is obtained. This computational technique is tested on a typical planar cable suspended manipulator. The experiment is performed to compare the calculated maximum load with the actual carrying payload on the path chosen for the comparison.

Whereas in electrical discharge machining (EDM) the heat flux entering the workpiece is extremely high, the Fourier heat conduction model may fails. This article reports on determination of temperature distribution in the workpiece due to EDM using non-Fourier heat conduction model. Equations are solved by deriving the numerical solution. The temperature layers and profiles of sample calculations show that it is not acceptable applying the Fourier heat conduction model for estimating the temperature of workpiece. Also, it can be perceived that according to the amount of Vernotte number for a specific Fourier number, it is possible that the temperature of different points of workpiece become even lower than initial temperature.

In the course of expansion in turbines steam nucleates to become a two-phase mixture, the liquid consisting of a very large number of extremely small droplets carried by the vapor. Formation and subsequent behaviour of the liquid lowers the performance of turbine wet stages. The calculations were carried out assuming that the flow is two dimensional, compressible, turbulent and viscous. A classical homogenous nucleation model applied for the mass transfer in the transonic conditions. The aim of the present study is investigation of outlet pressure effect on second phase generation in a steam turbine. The maximum and minimum of droplet numbers have been achieved and nucleation zone has been specified in blade passage. Pressure profiles around the blades are compared with the experimental data and good agreement is observed. Results show that the most condensation is on the suction surface of blade and it grows by decreasing the downstream pressure.

The paper investigates into the vibrational characteristics of the truck chassis including the natural frequencies and mode shapes. Truck chassis forms the structural backbone of a commercial vehicle. When the truck travels along the road, the truck chassis is excited by dynamic forces caused by the road roughness, engine, transmission and more. Modal analysis using Finite Element Method (FEM) can be used to determine natural frequencies and mode shapes. In this study, the modal analysis has been accomplished by the commercial finite element packaged ANSYS. The model has been simulated with appropriate accuracy and with considering the effect of bolted and riveted joints. The chassis has been altered by some companies for using in municipal service (street sweepers) and it raises the question: Are natural frequencies of the modified chassis in suitable range? After constructing finite element model of chassis and appropriate meshing with shell elements, model has been analyzed and first 6 frequencies that play important role in dynamic behavior of chassis, have been expanded. In addition, the relationship between natural frequencies and engine operating speed has been explained. The results show that the road excitation is the main disturbance to the truck chassis as the chassis natural frequencies lie within the road excitation frequency range. Finally advantages of the modified chassis which leads to the increase of the natural frequencies and placing them in the appropriate range, has been discussed.

The impact resistance of new lightweight panel is studied. This panel consists of two thin metal layers bonded together by intermediate fiber/epoxy layers (MCM-sheets). To simulate a behavior of this kind of impact problem, explicit and implicit finite element software ABAQUS is used. In order to validate the finite element modeling, these results have been compared with experimental test results. The Response Surface Method (RSM) is applied to minimize the dent depth and panel mass. After optimization of panel, the panel with optimum dimension is compared to uniform panels in different stuff. However, the MCM-panel displays a larger dent resistance and less mass than the aluminium and the steel panels.

Due to their advantages, omni-directional mobile robots have found many applications especially in robotic soccer competitions. However, omni directional navigation system, omni-vision system and kicking mechanism in such mobile robots have not ever been combined. This situation brings the idea of a robot with no head direction into existence, a comprehensive omni directional mobile robot. Such a robot can respond more quickly and it would be capable for more sophisticated behaviours with multi-sensor data fusion algorithm for global localization. The methods have been tested in the many RoboCup competition field middle size robots.

This paper deals with a globally convergent adaptive and sliding mode control of a cart-pole inverted pendulum for trajectory tracking in the presence of a bounded measurement noise and parameter uncertainty. Two kinds of controllers have been used for evaluation of tracking error in presence of a bounded noise; as a result, we want to compare that at what time we can see the convergence of tracking error and which controller can perform better? Simulation results on a cart-pole inverted pendulum are shown for trajectory tracking in presence of impulse disturbance.