Currently, the airbag is the most important and effective restraint system available on the market. Nevertheless, its activation is related to some facial, ocular and auditory injuries. The principal objective of this project was to develop an evaluation tool capable of predicting injuries to the face.
The project was designed because previous research shows that the above-mentioned injuries occur under velocities that vary in the limits of activation/no activation set by each manufacturer (ΔV < 48 km/h). The majority of these injuries occur in frontal impacts where the interaction between driver and airbag is the greatest.
Furthermore, shorter occupants (<1.60 m) tend to receive the most severe injuries due to their proximity to the airbag. The most common injuries are facial, ocular and skin abrasion. The noise produced by an activating airbag is generally over the safe limit for a person, and can cause permanent damage to the internal ear. The explosion is generated by the chemical reaction of gases that may produce intoxication or skin injury.
Therefore, the first task of this project was to evaluate the injury map related to airbag activation in frontal impact, although other configurations were considered. A revision of the state of the art and the direct relation with possible facial, ocular and auditory injuries and intoxication was also performed. The next task was to develop a set of testing procedures for the evaluation of the established injuries that airbag deployment causes to the occupants. To finalize, an assessment of the developed tools and protocols was made.
The project activities focussed on the development of a measuring system designed to predict facial and ocular injuries resulting from blunt impacts during contact with the airbag, estimating the risk of suffering facial bone fractures or severe ocular injury. This was accomplished through a special mask that measures the pressure applied at specific points of the head, such as nose tip, eyes, eyebrows, jaw, etc.
To estimate the risk of auditory injury, a specially designed dummy head made use of special microphones to measure the sound and pressure levels found in the cabin during airbag activation. This head can be used both in static and dynamic tests.
For intoxication and skin abrasion injuries, a protocol and a tool to measure the amount of toxic gases released from the explosion of the airbag was developed. In this particular case, the most relevant toxic gases were selected and the adequate instrumentation established for the development of the test.
With the three elements combined, an overall evaluation on the severity of the airbag system to be assessed can be generated, allowing manufacturers and designers to create more effective yet non-injurious systems.
The results of the project are in line with the proposed objectives, and the developed tools and the protocols are good enough to provide a more stringent evaluation of restraint systems and will also help in research regarding injury mechanisms in various accident configurations.