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Release: August 5, 1999

Team of UI engineers studies ‘physics’ of auto airbags

IOWA CITY, Iowa -- A team of University of Iowa engineers is studying how conventional airbags work in order to help researchers design safer airbags for new cars and trucks.

P. Barry Butler and L.D. Chen, professors of mechanical engineering and project co-principal investigators, are in the final year of a three-year, $369,000 General Motors grant funded through the National Highway Traffic Safety Administration. Chen says that the primary goal of the UI project is to understand the physics of auto airbags.

"We want to find parameters that can be used to describe the airbag inflation process. By knowing how current airbags inflate, automotive engineers can design futuristic airbags," Chen said.

The UI project is focused on the characteristics of passenger-side airbags, which in the past have saved many lives; however, passenger-side airbags have also been involved in the injury and death of some infants, children and small adults. Working in their UI College of Engineering laboratory, the research team, led by Butler and Chen, tested conventional airbags for characterization of airbag deployment and inflating processes.

Preliminary findings show that at least two modifications may enhance airbag safety, according to Butler, project leader and an expert in solid rocket propellants. First, reducing the amount of propellant used could lessen the explosive force with which airbags inflate. Also, in order to maintain the amount of gas needed to inflate the bag, an aspirator could be installed behind the dashboard to compensate for reduced propellant by sucking air into the bag.

Today, some so-called "smart" airbags available in new cars are able to perform such tasks as evaluating the weight of the passenger and adjusting the force of inflation accordingly. However, Butler noted that the ideal airbag may be many years in development because it is difficult to take into account all possible passenger variables. For example, a smart airbag should be able to determine whether an adult, a child, or a child seat is occupying the passenger seat and where that occupant is located, with respect to the dashboard, and modify its explosive force. In the meantime, Butler noted that he plans to continue the project for many years in the hope that it will further the cause of automobile safety.

"Our goal is to develop a set of diagnostics showing the airflow into and out of an aspirating, or air-breathing, airbag. The aspirating airbag is being considered as an alternative to conventional airbags while better airbags are being designed," Butler said.