Optimization of Three-Wheel Vehicle Roof Structures Against Rollover Accidents

The rollover safety of Three-Wheel Vehicles (TWVs) is critical because of its instability in severe steering, side collisions and flip-over compared to Four-Wheel Vehicles (FWVs). In order to evaluate the rollover safety, the roof crash conditions in various types of accidents are investigated to provide a reliable roof structure. In order to prepare for roof crash conditions for TWVs, investigation has been carried out in aids of multibody dynamic simulations and motion simulations. According to the simulation, the rear region of a TWV’s roof crashes onto the pavement in case of the rollover. To design an optimal roof structure of TWVs, topology optimization is utilized based on the roof crash conditions. The preliminary design of the roof structure from topology optimization is modified into eight different designs by changing the shape of a roof structure. In this paper, both a static crash test and a dynamic crash test are simulated to obtain the best design of the roof structure of TWVs. The dynamic crash test of a roof structure is essential because of the rate dependency of materials and evaluation of real crashworthiness. From the preliminary designs, an optimal shape of a roof structure is determined considering possible cases of actual rollover. The optimal shape shows that the front members of the cross-bar reinforcement and window screen member need to be straight and the rear member needs to be arch-shaped.