Testing adapts to new regulations

Safety testing is always a hot topic at the SAE World Congress. The issues surrounding safety test are both technical and political. Tests must produce results that are not only technically correct, but also politically palatable.

This is a good news/bad news situation. The good news is that constant political pressure on government regulators and automakers to improve automobile safety and safety-test methods helps the industry and consumers. The bad news is that the targets for test engineers are always changing.

This temperature chamber has several windows on each side to allow engineers to get the best view of airbag deployments. Courtesy of MGA Research.

Because airbags must deploy reliably when the ambient temperature is both very cold and very warm, manufacturers deploy them in a temperature chamber. To ensure that the airbags deploy properly, the authors make a high-speed video recording of the event, and then view the recording to check the deployment characteristics and airbag integrity. The problem is that most temperature chambers are not designed with this test method in mind. Rarely do commercial chambers have more than a single door, so test engineers are limited as to the angles they can use to record the deployment.

To address this problem, MGA built a temperature chamber specifically for static airbag testing. As shown in the figure, the chamber has many different windows. The windows allow the engineers to get the camera views they need, and they also provide the lighting needed for the test.

The authors went on to describe their work in synchronizing airbag deployment with dummy impacts. The key to this work is a system capable of accelerating a human body form into a deployed airbag. This system includes a pneumatic piston onto which a technician attaches the body form and a controller that deploys the airbag and injects a compressed gas into the piston to force the body form into the deployed airbag. A data-acquisition system measures the forces and accelerations experienced by the body form.

The paper also addressed the work MGA Research has been doing in response to changes in Federal Motor Vehicle Safety Standard (FMVSS) 201U, "Upper Interior Head Impact Protection" and FMVSS 208, "Occupant Crash Protection." The latest version of FMVSS 208, for example, requires testing to ensure that undersized occupants positioned close to the airbag are not seriously injured when an airbag inflates. The paper described some of the tests that MGA developed to meet these requirements and showed some typical test data.