Sub frame design method in vehicle

摘要

PURPOSE: A method for designing a sub frame of a vehicle is provided to output relatively exact data for the injury of passengers by regarding the energy dissipation for an engine room forming the front of a vehicle body, a restraint device restraining passengers, and the physical characteristic of passengers and accordingly to minimize the injury and make an optimum sub frame with a minimum weight. CONSTITUTION: A method for designing a sub frame of a vehicle is composed of steps of computing the values of an energy dissipation to the change per hour with a Lagrangian equation by applying kinetic energy and potential energy, which are computed according to the behavior of a passenger, to a generalized coordinate; optimizing an object function obtained by applying a weighting factor to the values of the energy dissipation and minimizing the injury of the passenger; modeling the sub frame by using the optimized data for the passenger; outputting the energy dissipation to the change of time by dividing the sub frame into a plurality of elements having a constant density(micron) and defining the elements as a function of density; and optimizing the object function, removing relatively unnecessary mass from the elements, and accordingly computing the optimum sub frame.