A Dual Airbag Loading Device for Uniform and Controllable Pressure Application in Adhesive Curing

Abstract Achieving uniform pressure is a key process requirement in the adhesive curing of thermal protection systems for hypersonic vehicles, and it directly affects bond quality and structural reliability in service. To meet the engineering demand for uniform and controllable loading during the curing of curved metallic shells, this study investigates the pressure distribution characteristics of the airbag-based loading method. First, a pressure dynamic model for the airbag during the inflation and pressure holding stagesis established, and a closed-loop pressure control method is developed to achieve stable control of the internal airbag pressure. Based on this model, a dual airbag staggered loading scheme is proposed to address the circumferential pressure non-uniformity observed in single airbag loading, which is mainly caused by seams, wrinkles, and differences in contact conditions. The pressure distributions under single airbag and dual airbag loading are then compared experimentally. The results show that, at a target internal pressure of 60 kPa, the dual airbag staggered configuration reduces the circumferential pressure range by about 44%, leading to a clear improvement in loading uniformity. The proposed dual airbag loading scheme can effectively improve the loading quality during thermal protection bonding and curing without a significant increase in control system complexity, and provides a simple and practical flexible solution for uniform pressure application in engineering practice.