When hovercraft flies on cushion at high speed, only skirt fingers below skirt bag contact with operating surface of water or land, which endures complex loading at harsh operation environment. Side skirt fingers were prone to damage and caused huge cost of damaged finger replacement. Through analysis, it could found that operating trim attitude and forward with sideslip are the main reasons for side finger with more likely damage. Based on application development in ABAQUS, skirt finger deformation after immersed into water was digital simulated, which agreed with actual damage mode. Through analysis, advice for enhance life of side skirt finger were presented and also attentions need to be pay on its membrane structure design.
Hovercraft (Air Cushion Vehicle) flexible skirt attached around the entire side-low and bottom edges of hull buoyancy box, would inflate into design shape acted by high pressure airflow from lift fan to form cushion and hover the hull over operating surface(Yun and Bliault, 2000). As one of the unit systems of ACV, flexible skirt is fabricated by thin rubber coated material and belongs to membrane type structure. The upper part of typical skirt is continuous bags, with individual fingers attached to the bottom of bow and side bag, while a lot of individual cones or little loops attached to stern bag (Ma and Wu, 2012). The function of flexible skirt is similar to hull shell of traditional displacement ship, which endures slapping and erosion of wave, friction and crash of terrain, undulate ground surface and obstacle. So, skirt belongs to life piece, and loads acted on skirt fingers are more sophisticated and ugly, which result in damage to finger low tip and shorter life. Wiggins et al. tested finger deform of bow seals immersed into water at the US Navy's Large Cavitation Channel and also processed by analytical/numerical approaches, some new details were found (Wiggins, 2014), (.García-Espinosa, 2015). "At sea" experience on full scale ship displayed that skirt fingers located at aft part of side skirt have more possibility of damage and higher replacement frequency. Effected by ACV trim, velocity and sideslip in high frequency, force acted on side skirt finger was more complex and changeable (Chen, Zhu, Gu, Gao, 2021). Following will analysis loading characteristic of fingers located at bow, side, stern, and forward some attentions need to pay to finger structure design.
