Modeling of Adaptive Energy Absorbing Steering Columns for Dynamic Impact Simulations 2014-01-0802
The objective of this paper focused on the modeling of an adaptive energy absorbing steering column which is the first phase of a study to develop a modeling methodology for an advanced steering wheel and column assembly. Early steering column designs often consisted of a simple long steel rod connecting the steering wheel to the steering gear box. In frontal collisions, a single-piece design steering column would often be displaced toward the driver as a result of front-end crush. Over time, engineers recognized the need to reduce the chance that a steering column would be displaced toward the driver in a frontal crash. As a result, collapsible, detachable, and other energy absorbing steering columns emerged as safer steering column designs. The safety-enhanced construction of the steering columns, whether collapsible, detachable, or other types, absorb rather than transfer frontal impact energy. Recently, more advanced steering column designs with adaptive features, mechanically or pyrotechnically activated, have been introduced for different crash conditions, including different crash severity, occupant mass/size, seat position and seatbelt usage. These steering columns are able to absorb different impact load conditions ranging from high impact load for larger and/or unbelted crash dummies (95th-male and 50th male, respectively) in higher severity crash tests to low impact load for smaller (5th female dummy) and/or belted drivers in lower severity crash tests. With the steering column designs becoming more complex, the modeling of a steering column with advanced safety features also becomes more challenging.
To optimize prototype testing and enable faster development cycle time,, an attempt was made to model the steering assembly with advanced safety features. The modeling study was divided into two phases, with the first phase focusing on the modeling of an adaptive energy absorbing steering column as discussed in this paper. The modeling of an advanced steering assembly, with a safety-enhanced steering wheel and an adaptive energy absorbing steering column for frontal and side impact simulations, was developed in the second phase of the study and will be presented separately . To provide information for modeling methodology development, component and sub-system tests were developed and conducted to understand the mechanical behaviors of different energy absorbing features as well as the performance of the adaptive mechanism in the steering column design. Different dynamic impact speeds, including quasi-static tests, were also included in DOE test matrices so that collapse speed sensitivity of the steering column components could be obtained. Finite element modeling methodology was developed and presented based on its correlations with the steering column component and sub-system tests.