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The FMVSS 201 regulation requires that interior components in upper compartment of a passenger vehicle pass a head impact test using a Free Moving Head (FMH) model with a HIC(d) limit. In this type of test, most interior components themselves do not generate high HIC(d) numbers but the steel structures underneath these components do. In addition to normal functions, interior components need to absorb the kinetic energy of the FMH model such that the acceleration response of the FMH model does not generate a high HIC(d) number in the test. This paper first reviews the existing work on the principles for the head impact protection and identifies limitations of the existing theory for the design of the interior components that are mounted on flexible structures. This paper discusses and proposes a design methodology for automotive interior components to ensure that they comply with FMVSS 201 head impact requirements.

Current performance specifications of seat belt pretensioners include web retraction and belt load. These criteria may adequately represent the performance requirements of a pretensioner in a restraint system. However, by themselves, they are inadequate to evaluate potential design modifications to improve efficiency levels and thus increase energy output of the pretensioner. This paper demonstrates a non-linear phenomenon associated with web retraction and the belt load during pretensioning. It is this non-linear behavior that promotes the insensitivity for use of web retraction in predicting the energy output of a pretensioner with design modifications. This paper proposes an energy measuring method that can be used to more accurately measure the energy output of a pretensioner and then be used to evaluate the effects on output of a pretensioner due to design modifications.

Constant force retractors are a new type of seat belt retractors which, during a crash, can generate nearly constant belt restraint forces on occupants required by advanced restraint systems. There are several types of designs to provide the constant belt force by retractors. The torsion bar is one of them. In this type of design, a metal bar is designed to take the belt load in the torsional mode then to yield at a preset load level and keep the belt load at that level for a certain amount of belt pay-out. This paper first presents the theoretical design of the torsion bar. It applies material plasticity to derive all the equations for the design of torsion bars with circular cross sections. These formulas include the relations between required constant force and belt pay-out, diameter and length of the bar, material properties, and torque to rotation properties. This paper also includes formulas to guide the designs based on prototype test data.

This paper demonstrates how to use advanced finite element modeling techniques such as airbag modeling, material plasticity with consideration of failure and effects of temperature and strain rates, surface to surface sliding contact treatment, nonlinear transient dynamics, and so on, to perform structural analysis of airbag modules. A technique to calculate the transient dynamic loads on the structure of an airbag module is first demonstrated. The dynamic transient loads on the structure are calculated by an integrated airbag modeling and sliding contact treatment with the structural model of the airbag module. Other techniques for modeling special design features of the airbag module, such as tear seam, tear tie, and hinge on a cover, press fit of a gas defuser, housing, connections of each component, and so on are also illustrated and discussed. All modeling techniques are illustrated by analysis examples in product development.