Showing 4 results for Rezapour
Dr Javad Rezapour, Eng Parvaneh Afzali,
Volume 10, Issue 3 (9-2020)
Abstract
Rollover of sport utility vehicles is a critical challenge for dynamic stability of the vehicle. Due to the high rate of fatalities resulted from the rollover, in order to reduces the injuries, the design of active vehicle controllers has received significant attention among the researchers and car companies. In this article, a multi-criteria optimum method is discussed in order to design a dynamics stabilizing controller via differential braking with an optimum braking torque distribution. To this end, the nonlinear control method on the basis of the sliding mode techniques has been implemented that provides ride comfort, improve safety performance, and maintain maneuverability. To address the trade-off between the conflicting requirements of vehicle dynamic control in terms of maneuverability and rollover prevention capability, we formulate an artificial intelligence-based multi-criteria genetic algorithms. The simulation verification analysis indicates that the utilized optimum distribution braking torques result in the desired enhancement in roll stability of the vehicle.
Arman Mohseni, Javad Rezapour, Sina Gohari Rad, Reza Rajabiehfard,
Volume 12, Issue 2 (6-2022)
Abstract
Background: Hydroforming is employed in the manufacture of hollow monolithic products to reduce the number of joints. This method can reduce the weight and enhance the quality of fluid transfer parts in a vehicle’s hydraulic system. Hydroforming is a process in which parts are formed into the shape of a mold using fluid pressure. An important issue in this process is adopting an optimal loading path. Methods: In the present research, a drop hammer was used to implement the dynamic loading path in the tests. Accordingly, a single energy source was used simultaneously to provide axial feeding and internal pressure. To this end, designing a mold suitable for the dynamic loading path was necessary. Results: This numerical study investigates tubes’ deformation based on the applied impact and the amount of fluid in the mold. Moreover, axial feeding was provided with the help of different punches on the sides of the tube. Hence, the kinetic energy, amount of fluid, sealing, lubrication, and the material and thickness of the tube must be proportional for the correct forming of the tube. From the smoothed-particle hydrodynamics perspective, it is a meshless method based on interpolation that uses a particle system to examine the system state and predict fields such as displacement, stress, and pressure. Conclusions: One of the main observations of this research is that selecting side punches with a smaller central hole radius is proportional to the kinetic energy and the amount of fluid. that is effective in achieving the optimal loading path.
Dr. Hossein Bagherian Farahabadi, Mr. Amirhossein Pahnabi, Mr. Reza Youneszadeh, Dr. Mohammad Ali Alirezapouri, Mr. Mohammad Rezaei Firuzjaei,
Volume 13, Issue 1 (3-2023)
Abstract
One of the most important components of fuel cell power systems is the power conditioning subsystem. DC/DC converters play the leading role in the power conditioning subsystem and fuel cell hybridization with other electric power sources and storage. DC/DC converters control the load voltage and, in some cases, the fuel cell current, while current-controlled DC/DC converters control the loading level. Some advantages of designing converters in a multi-layer topology include reduced input current ripple and increased power density. Lower current-rating semiconductor devices can be used due to the current division among the layers and lower values of inductors and capacitors can be used due the lower input current and output voltage ripples, respectively. Furthermore, failure of one layer does not result in a complete system outage; the other layers can deliver a fraction of the nominal power. A fuel cell power system based on a 16 kW proton exchange membrane fuel cell stack and a multi-layer DC/DC boost converter is designed and implemented in this paper. The power system is intended for marine air-independent propulsion systems. The power system is modeled and analyzed using the MATLAB/Simulink software environment. The power system is implemented to verify the analysis and simulation results.
Farid Raoof, Javad Rezapour, Sina Gohari Rad, Reza Rajabiehfard,
Volume 13, Issue 2 (6-2023)
Abstract
Thin-walled tubes can avoid the transition of injurious acceleration and excessive forces to the protected section and minimize the damage severity. They absorb energy under axial loading circumstances as crashworthiness structures. The present study deals with the investigation of the density effects of foam on the quasi-static loading response of foam filled and empty cylindrical tubes. To investigate energy absorption parameters by varying in foam density, two different densities of polyurethane foam were used to evaluate the efficacy of polyurethane foam density under axial quasi-static loading. According to the results, the use of foam as a filler also influences the tubes’ deformation behavior in addition to the effects of thickness. It was revealed that by incrementing the thickness to 20%, the peak load increased by 25.2%. Two densities of foam were considered as 40 and 85kg/m3 to assess the effect of density of polyurethane foam as filler on the energy absorption behavior of tubes under axial loading. Result showed that when foam density increased by about two times, the peak load increased by 1%. According to the results, filling tube by foam also influences the tubes deformation behavior in addition to the effects of thickness
