Research On The Cushion Mechanism And Property Of Airbag In A Dropping Manner

Airbag, as a novel air cushioning material, is made of plastic bag filled with gas. And its cushion property is provided by the gas filled in sealed chambers, which gives it lots of advantages both in shock absorption and vibration isolation.In this paper, an existing geometry model which treated the airbag as a horizontal cylinder was used to study the geometry property of the airbag, while an improved model was proposed then. Both the equivalent static compression and simulated dropping test were employed to validate the applicability of those two models. After that, the cushion properties of the airbag and the effect of the designing parameters on those properties were discussed thereafter.At first, the relationship among the maximum internal pressure of the airbag, the strength of the check valve and the thickness of the airbag was evaluated by using the peel test of the check valve and the burst test of the airbag. It is found that the maximum pressure increases as the thickness decreases. And then, both geometry models were analyzed, which led several results. The contact area of the airbag grew with the increase of the deflection linearly. In the equivalent static compression, horizontal cylinder model was more suitable for the small size airbag and the improved the larger. And so did the results in the simulated dropping test. While the deflection exceeded to some extent, the theoretic value overestimated the loading property of the airbag. In predicting its dynamic cushion property, the improved model was more suitable by comparing the test and theoretic value. In addition, the distortion of the film was taken into account, which showed that the effect of the film was only concerned in the dynamic test.At second, the cushion property of the airbag was evaluated. In the equivalent static compression, the cushion coefficient decreased as the initial pressure grew. But when the pressure exceeded 60kPa, the trend for the decrease was slowed. And the minimum cushion coefficient always happened between the value of 2.5~3, when the strain of the airbag was of 0.4~0.6. The effect of initial geometry was not obvious. In the simulated dropping test, the cushion property was strengthened as the initial pressure grew. When the dropping mass grew, the maximum acceleration increased for 60-115, and 40-115. For 30-115, the maximum acceleration decrease at first, and then increased.In the end, after evaluating the cushion properties, a method was proposed to make the 6-step-method of the traditional cushion package design more suitable for the employment of the airbag. In this manner, the 4th step was optimized, in which Gm～n curve was used to assist the design of the air cushioning packaging.