Abaqus Multiphysics / CEL / CEL Example

Automotive Airbags for Occupant Safety

Challenge

Airbags provide occupant safety in automotive crashes by deploying at an extremely high rate upon impact. Typical airbags reach a fully inflated state in about 50 milliseconds, ideally prior to contact with the vehicle occupant. Recently, interest has focused on out-of-position occupant scenarios, wherein the occupant contacts the airbag prematurely, before it is fully deployed. In this case, inflator gas flow within the partially deployed bag plays a primary role in the severity of the occupant/airbag interaction. Accurate simulation of the gas/airbag/occupant interactions requires a fluid-structure capability.

Solution

Occupant/airbag interactions involving fully deployed airbags are routinely simulated today by representing the effect of inflator gas as a uniformly distributed pressure inside the bag. This uniform pressure assumption is approximate during the early stages of deployment, so for out-of-position occupant scenarios the inflator gas flow inside the airbag can now be modeled using Eulerian technology in Abaqus. The gas/airbag interaction is captured by an extension of Abaqus' easy-to-use general contact feature, which automatically computes the gas/airbag interface, applies constraints to prevent gas leakage, and creates non-uniform pressure on the airbag surface.

Results or Benefit

The Eulerian technology in Abaqus provides enhanced simulation accuracy during the early stages of airbag deployment by eliminating the assumption of uniform pressure distribution within the airbag. This capability is necessary for accurate safety evaluations of out-of-position occupant scenarios in automotive crash safety.