AMIRKABIR
Year:2004 | Volume:15 | Issue:57-B (TOPICS IN: MECHANICAL ENGINEERING)|Papers Count:5

Proof of concept experiments on the use of the chemical electroplating technique in manufacturing copper-constantan thermocouples are conducted The thermoelectric voltage of the thermocouples are measured and power produced are calculated. The See beck coefficient of the electroplated thermocouples was found to be lower than the standard T-type thermocouple. Microscopic pictures of the junction revealed some possible causes of inferior performance and remedies are proposed to improve performance. The technique is suggested for mass production of thermocouples for various applications.

In this paper kinematics model of a nonholonomic mobile manipulator is formulated. The kinematics equations for a mechanical mobile manipulator are developed in such a way that the kinematics interaction between the mobile platform and mechanical manipulator explicitly appears in the equations. In both conditions the motion constraints and kinematics redundancy are considered and analyzed. These concepts are expanded in general cases by using special subjects, on linear algebra and functional analysis. A useful and unique kinematics model for redundancy resolution of mobile manipulators is introduced by defining specified variables. Finally, the application of the model is verified by simulation results in order to find the maximum allowable load of a mobile manipulator.

In this paper, theoretical and numerical model for penetration of deformable projectiles into metallic targets is presented. The analytical model is based on the propagation of longitudinal plastic stress wave in projectile and plug also shear stress wave in outer region of plug. The projectile and target materials are adapted to Johnson-Cook equations without considering the strain rate and temperature effects. The results of this paper are compared with experimental results and finite element modeling with LS-DYNA software. The theoretical ballistic limit velocites are in a good agreement with experimental and numerical results. In this model the solution of governing equations is easy and it will be a new method in modeling the penetration process by using stress wave propagation.

One of the applications of distributed moving heat source is forming steel components by flame bending process. In the process simulation, determination of temperature distribution in work pieces is very important. For this purpose, the 3D transient heat transfer equation must be solved. In present study, Considering input heat flux as Gaussian distribution with free convection and, radiation boundary conditions, a model is given to analyze heat transfer during flame bending process of steel plates. For this model, a computer program has been developed by using finite element method. To verify the model and program, some examples are analyzed and their results are compared with those of the other researchers in given cases. From obtained results, it has been shown that the process is under influence of torch speed, effective power and concentration coefficient of flame, plate thickness and boundary conditions including of free convection and radiation.

In this paper, an analysis for penetration of cylindrical projectiles into metallic targets at normal obliquity is developed by using propagation of longitudinal and shear plastic stress waves theory. During penetration, projectile deforms failure of target plate is assumed to be in plugging with dishing mode. In this model, projectile penetration into target is classified in six stages and for each and failure stage, the governing equations of motion of projectile and target are derived. We have presented a model for dynamic deformation of outer region of plug, Also, a dynamic behaviour of target is assumed to be like rigid-work hardening. The analytical results of this paper are in good agreement with experimental results.