THE NUMERICAL SIMULATION OF THE PYROTECHNIC ACTUATOR FOR THE ACTIVE BUMPER

The paper contains the description and classification of pyrotechnic actuators focusing on the automotive industry applications. This paper also explains the compatibility issues during frontal impact of a passenger car with a large truck. The construction of the pyrotechnic actuators for the “active bumper” is presented here. The processes occurring within the pyrotechnic actuators after ignition of a pyrotechnic propellants have been explained. The investigations are focused on the dependence of a shape of the actuator’s combustion chamber and the piston stroke time. It appears that the appropriate design of the combustion chamber can decrease the time required for a piston stroke using this same type of a propellant. This also allows to reduce the amount of propellant when the more rapid stroke is not required. This is because of the characteristics of the detonation waves which are responsible for the piston movement. The visualization of the detonation waves occurring due to ignition of the propellant is crucial for understanding the dependence between the construction of the actuators interior and the piston stroke time. Therefore, the approach of simulating numerically the detonation waves aroused. This simulation was conducted with aid of ANSYS Workbench 13 environment using the AUTODYN module. The numerical tests consists on modelling the actuator without changing the overall dimensions as well as the parameters of the propellant. The only elements modified were piston and the bottom of the cylinder shape.