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.
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
