In this paper, dynamical behavior of the delay mechanism of a special projectile controller is studied, using 3D finite element simulation. The controller considered here is among of high-acceleration mechanical controllers. Due to high linear and angular accelerations of the projectile and also explosion risk, experimental investigation is very limited and almost impossible. So, numerical simulation is a valuable tool for designing of this kind of controllers. In the simulations here, the metal coil and its ring belt are the deformable parts of the model, while other parts are assumed to be rigid. Plastic deformation of these deformable parts, during the projectile motion, has a very important effect on the proper operating of the controller. To study the effect of coil material properties, a bilinear stress-strain curve with different yield stress was assumed. The simulation results show that there is an optimum yield stress for the metal coil, by which the appropriate operation of controller may be reached. For the special controller considered here, this optimum yield stress is about 285(MPa). All simulations made use of ABAQUS commercial software. تفاصيل المقالة

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. تفاصيل المقالة

Cold roll-forming is a process in which the roll of sheet is formed by passing continuously through the set of rotary rollers without changing thickness in a cool way until it is formed to the desired profile. In this paper a parametric study on the section twist angle in roll-forming the non-symmetric channel is presented, using finite element simulation. At first finite element simulation results are validated by comparing the computed longitudinal strain, near the flange edge, with previously published experimental strains, for a special symmetric channel section. Here symmetric channel section was considered for verifying the finite element results, because of the lack of previous researches on non-symmetric channel section. Then by repeating the finite element simulation for similar section but with different flange width and changing the geometrical parameters such as flange width difference, sheet thickness and profile angle the effect of these parameters on twist angle is investigated. Investigating the results show that section twist angle is increased by decreasing the profile angle and sheet thickness and by increasing the flange width difference. All simulations were carried out using the commercial software ABAQUS 6.7. تفاصيل المقالة

Reshaping process is a widely used method for producing tubes with non-circular cross sections. Owing to the friction between pipe and rolls, initial round pipe moves forward and consequently, it gradually formed into square or rectangular one. In practice, geometric profile of the rolls will be changed after a while. These changes would be detrimental the production of faultless products. Therefore, in this paper the reshaping process is studied considering wear phenomena on the rolls. This study is a co-operation with a related industry at which square tubes are produced using reshaping process. In order to investigate the production line, considering industrial datasheets, the process is modeled by means of a commercial FEM package, ABAQUS\Explicit. The reshaping process is simulated as a 3D model and subsequently the sustainable regions to wear are investigated. The influences of significant parameters such as material and thickness of strip, as well as friction coefficient on the worn area, are studied. At the end, the FEM reults are comprised with the experiments reults and a good consistency between them is seen. تفاصيل المقالة

In this study, dynamic behavior of safety mechanism of a mechanical controller is investigated using 3D-FE simulation. This paper is concentrated on controller of a high acceleration projectile. The controller is located in the top of the projectile. Safety mechanism is divided to deformable and rigid parts. Deformable and rigid parts are simulated in Abaqus and Adams commercial soft wares; respectively. The goal of this study is to investigate the safety mechanism operation includes plastic deformation of safety ring, rotor rotation and the required time for this operation. Also, some important parameters of safety mechanism such as, determination of required time and angular velocity for plastic deformation of safety ring, exit of safety pin, and the angular velocity correspondent to rotor rotation, when the axis of needle and guide hole are aligned, are studied. تفاصيل المقالة