INTERNATIONAL JOURNAL OF ADVANCED DESIGN AND MANUFACTURING TECHNOLOGY
Year:2010 | Volume:3 | Issue:2 (10)|Papers Count:8

In this research optimal reconfiguration strategy of the improved SRR reconfigurable mobile robot based on Force-Angle stability measure has been designed using Genetic algorithm. Path tracking nonlinear controller which keeps robot’s maximum stability has been designed and simulated in MATLAB. Motion equations of the robot have been derived in parametric form by means of Newton- Euler, Lagrange and Kane dynamic methods using MATLAB symbolic toolbox. The robot has been simulated using ADAMS software for optimization evaluation. Path and velocity of the vehicle and end-effectors and the terrain function below vehicle’s wheels have been already defined. Reconfigurable mobile robots increase their stability in rough terrain by static or dynamic reconfiguration or by means of mass-center quasi-static transportation or dynamical reconfiguration during motion. Extendable Newton-Euler, Lagrange and Kane dynamic methods algorithms to other kinds of robots have been designed for dynamic modeling of improved SRR reconfigurable mobile. Spatial complex dynamic equations of improved SRR have been derived in parametric form by means of those dynamic methods using MATLAB symbolic toolbox. Furthermore, the robot has been simulated using ADAMS software for evaluation of dynamic model.

Based on two-dimensional plane stress and bifurcation functional from Hill's general theory in polar coordinate the critical condition for elastic wrinkling of the flange of a circular blank ( the wave number in the flange and wrinkled area) during the deep-drawing process are obtained analyticaly to improve the previous given results. In this analytical study, the elastic limitation of the material is also considered and to derive the bifurcation functional, the small and large deflection theoris are used and their results are compared to each other. The main advantage of the current research is obtainting an explicit solution and using the large deflection theory to detemine the critical conditions at onset of wrinkling.

Deformation Length is one of the most important parameters in cold roll-forming process, which plays a fundamental role in determining the inter-distance between the stations and rate of deformation. Deformation length was first introduced by Bhattacharyya. He also obtained a closed-form relation for this length in roll forming of symmetric channel section. In this paper, deformation length in the roll forming of the circular cross section is examined and determined. To do this, analytical method and finite element simulation are used. The analytical method presented in this paper is based on the approach of Bhattacharya's suggestion. Due to the fact that the deformed sheet geometry is more complex, hence the related equations of strain and deformation energy would become more complex too, and therefore analytical solution is going to be more difficult compared to symmetric channel section. Using the present analytical method, deformation length is computed for a specific numerical case study and the analytical results are compared with the results of finite element simulation of the ABAQUS commercial software. Correlation between the analytical and finite element simulation results demonstrates the validity of the presented analytical method. In the end, the effects of forming parameters on the deformation length are studied.

In this paper, free convection in an inclined stepped chamber has been studied. One wall of this enclosure is kept cold and the opposite wall equipped with constant heat source. The remaining walls are maintained adiabatic. There is one adiabatic step on the bottom wall. The aim of the present study is to forecast the effect of Raleigh number, slope of enclosure, step dimension, and heat source position, on the stream field, temperature and heat transfer rate. In this regard, two dimensional equations of mass conservation, linear momentum and energy are solved by applying finite volume method and simple algorithm. Results indicate poor effect of enclosure slope, step height, and position of heat source in small Raleigh numbers, however in large Raleigh numbers significant effects on fluid and rate of heat transfer of enclosure are observed.

Mixed convection is a fundamentally significant heat transfer mechanism that occurs in selection industrial and technological applications. In this study, first the laminar mixed convection inside rectangular enclosure with moving wall and Aspect Ratio=10 is modeled and then the results are compared with other investigate. After showing varity of results, the investigation is continued with turbulent flow using RNG k-e  and standard k-e. The results indicate that the turbulence intensity depends on the position. For example, in vertical walls and boundary layer, the flow is laminar and it is in the center of enclosure turbulent.

In recent year, the evolutionary structural optimization (ESO) method has been applied as an effective tool for structures design. The concept of ESO method is to use the finite element results in each iteration of process and removal of inefficient material based on these results. In this method there are several experimental parameters such as rejection rate and evolutionary rate that are effective in results. This paper studies the influence of elements according to orders and in this regard has been applied eight node element and in addition to that it compares whit four node element results, is investigated influence in stress value, volume reduction, other parameters such as evolutionary rate and rejection rate. The results show that some parameters for low order elements are not suitable in high order elements problems and there for, has represented adequate value parameters. several examples are provided whit various boundary condition.

In this study, dynamic behavior of a controller's Self Destruction mechanism has been simulated using 3DFEM in Adams software and investigated. This paper has been concentrated on high acceleration controller's projectiles. This controller is mechanical and has been placed in top of the projectile. The goal of this study is to investigate the destruction mechanism operation i.e. movement of pin and balls to up and returning back. Also, the time and angular velocity for beginning of these movements which are important in this mechanism are studied. Finally, the simulated phenomena have been compared with available data qualitatively. This comparison confirms validity of the simulation.

Harvesting practices of potato is one of the most difficult, troublesome and sensitive stages. Potatoes enter the machine with huge amounts of clod and stones: In the meantime separation of potato some stone and clod, which are the same size as of that the potatoes, shall be confide red a major problem. Many methods of study by investigators are based on physical properties of potato, stone and clod. In the present research with regards to the farm conditions and economic situation of the Iranian farmers, the beveled conveyor method is recommended. In this method, primarily a schematic design of the separating section of the stones and clod and the crop was produced and important parameters such as the surface angle, conveyor-belt motion speed and type of the conveyor, which play a key role in the separation stage, were studied. The test was carried out on the factorial basis and complete random block, using 3 angles factors in 5 levels (5, 10, 15.17.5 and 20 degrees) and the speed on 5 levels (100, 200, 300, 400 and 600 RPM) and the belt type with 2 surfaces (soft and rough) repeated 5 times. The SPSS software was used to analyze data. The result revealed that the ideal combination of the angle, speed and belt type for acquiring the highest separation rate and the least amount of mix clod, stones of the separated potatoes are the order, and the crop would be the angle 15 degrees, the speed of 300 RPM, with the use of soft belt, and the angle of 17.5 degrees and the speed of 200 RPM is recommended for a rough belt.