Fundamental physics and numerous field studies have clearly shown a higher injury and fatality risk for occupants in smaller and lighter vehicles when colliding with a heavier, taller and a higher one. The consensus is that the significant parameters influencing compatibility in front-toside crashes are geometric interaction, vehicle stiffness, and vehicle mass. The objective of this research is developing a concept of deployable bumper and grille airbags for improved vehicle compatibility in side impact. The external airbags, activated by signals from pre-crash sensors, may help mitigate the effect of weight, geometry and stiffness differences and reduce side intrusions. However, a highly reliable precrash sensing system is required to enable the reliable deployment, which is currently not technologically feasible.
Analytical and numerical methods and hardware tests were used to help develop the deployable external airbags concept. A simplified springmass model was initially developed to set the target for bumper and grille airbags parameters. Finite Element (FE) models of the inflatable structure (bumper airbag) were developed and exercised. Several iterations were executed to help develop the airbags and guide efficient test plans. The concept development was executed and validated in two phases. This paper covers “Phase I” only, which consists of extensive analytical, simulation and test iterations to achieve the inflatable structural system design for integrity and performance on component, subsystem and VIA sled testing levels. Examples of Phase I tasks were: Fabric Material testing and evaluation for ultimate strength and module of elasticity properties; Sewn versus bonded airbag construction technique; Airbag vent types; Overall bumper and grille inflatables and canister design and fabrication; and VIA sled testing to evaluate inflatable design, integrity and performance.
For the initial assessment of the inflatable system, a 48 kph perpendicular side impact of an SUV-type impactor against a stationary passenger car equipped with a US-SID-H3 crash dummy mounted on the sled was executed. Test results in terms of the airbags initial parameters, Head Injury Criteria (HIC), Thoracic Trauma Index (TTI), and Pelvic acceleration for the SIDH3 dummy, with bumper and grille airbags, were compared to those of baseline test results with no external airbags. This Phase 1 of the study was deemed successful in achieving the initial design parameters of the airbags, their integrity and their deployment and successfully staged the research for Phase II. The Phase II research investigated the concept of the inflatables and pre-crash sensing development, and was beyond the scope of this paper.
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