چكيده به لاتين
Annoying noises inside the cabin affect the comfort of the occupant. vehicle designers consider vehicle acoustic requirements as one of the main criteria in design. Sound insulation is one of the tools that reduce the entry of these unpleasant sounds into the car cabin. In this dissertation, first, the acoustic properties of the porous material used in firewall and bonnet insulation of Dena vehicle are calculated in reverse. Genetic optimization algorithm has been used to calculate these properties, which include porosity, Tortuosity , flow resistance, viscosity characteristic length and heat characteristic length. In this way, the absorption diagram obtained from the impedance tube as the input of the genetic algorithm and its objective function is the error of the limp porous material model. In the next step, the bonnet and firewall insulations of Dena Vehicle are simulated in VA-One software based on the properties obtained in the previous step. To simulate in VA-One software, the existing geometry is first elementalized by HyperMesh software and then transferred to VA-One software. To improve the insulation of the bonnet, two geometries of the old and new engine doors have been simulated in VA-One software that The old bonnet insulation has the same thickness of 3 mm and the new bonnet insulation has a coverage percentage of 3 mm and 12 mm depending on packaging. To improve the insulation performance of Dena firewall, several different configurations of porous materials and elastic layers have been considered. These configurations are simulated in VA-One software and its experimental test is performed by impedance tube device. These different compounds have been used to simulate firewall insulation. Finally, the best combination for use in firewall insulation has been selected
