Direct Folding Method of Cylindrical Airbag and Its Application in Landing Buffer.

The cylindrical airbag is widely used in the landing buffer field with a simple structure. It is a three-dimensional closed structure, so the folding model is difficult to establish. Because the modeling process of the existing methods is complex and these methods are difficult to use in the actual folding process, a new direct folding method was proposed in this paper. In the method, the two end faces of the cylindrical airbag are recessed inward, and the cylindrical surface is flattened into a sheetlike structure; then, its finite-element model is established. The folded cylindrical airbag was inflated, and the deployed shape was the same as that of the initial unfolded model after inflation. Moreover, the maximum errors of the equivalent cross-sectional diameter, maximum length, and volume of the inflated airbag were less than 4%, which shows that the method is reasonable and feasible. Based on this method, three finite-element models of cylindrical airbags in different folding states were established, and then the effects of folding mode, inflation rate, and ambient pressure on the deployment process of the folding airbag were studied. In the landing buffer analysis, this method was used to model the folded secondary airbag when establishing the finite-element model for the cushioning dynamic of the combined airbag. The simulation results are in good agreement with the drop test results, which also verifies the effectiveness of this folding method. [ABSTRACT FROM AUTHOR]