Automotive Occupant Dynamics Optimization

Abstract

One of the more difficult optimal design tasks occurs when the data describing the system to be optimized is either highly nonlinear or noisy or both. This situation arises when trying to design restraint systems for automotive crashworthiness using the traditional lumped parameter analysis methods. The nonlinearities in the response can come from either abrupt changes in the occupants interaction with the interior or from relatively minor fluctuation in the response due to the interactions of two restraint systems such as belts and airbags. In addition the calculated response measures are usually highly nonlinear functions of the accelerations. Two approaches using an approximate problem formulation strategy are proposed. One approach uses a first-order approximation based on finite difference derivatives with a nonlocal step size. The second and more effective approach uses a second-order curve fitting strategy. Successful example problems of up to 16 design variables are demonstrated. A conservative design strategy using a derivative-based constraint padding is also discussed. The approach proves effective because analytical expressions are available for the second-order terms.

Optimization of Multibody Systems Using Approximation Concepts

“…The second approach starts from a complex, usually finite element, crash model and an optimization strategy that can handle non-smooth functional behavior. Bennett and Park (1995), for example, used sequential linear programming with somewhat larger finite difference steps to calculate the sensitivities, as well as Vanderplaats' multi-point optimization method (Vanderplaats, 1979).…”

Design of the occupant protection system for frontal impact using the axiomatic approach

“…Crash regulations have been strengthened owing to technological advances and social demands. Extensive government regulations for many impact conditions make the design and optimization of the OPS challenging work [15][16][17][18]. The design of the OPS is carried out on the basis of regulations for several vehicle impact speeds.…”

“…The dynamic test of FMVSS 208 requires use of the 50th percentile male dummy in a 48 km/h barrier test. Using the regulations, research has been conducted for the design of the OPS by the response surface approximation methodology and optimization with orthogonal arrays [15][16][17][18]. NHTSA published an amended version of FMVSS 208 for occupant safety [13,14].…”

Determination of the crash pulse and optimization of the crash components using the response surface approximate optimization

“…Therefore, it is very di cult to design them simultaneously. Their characteristics and relations have been extensively studied in previous work [4,25,27,28]. However, simultaneous consideration in design can be easily obtained in the optimization process.…”