Research on dynamics of synchronous deployment of supporting mechanism and cylindrical envelope used for individual escape capsule

The emergency escape equipments are indispensable for submarine design. Due to the constraint of the narrow space, it is currently a matter of focus to design an individual-escape-capsule which can be folded and deployed quickly and be launched from torpedo tubes. In this paper, a foldable cylindrical individual-escape-capsule including rigid deployable supporting mechanism and elastic envelope is proposed inspired by Kresling origami. The mobility of deployable supporting mechanism is analyzed based on screw theory. Its constraint screw system and reciprocal screw system are obtained and corresponding helical motion with variable pitch is obtained to establish the solution models of kinetic energy and gravitational potential energy. An approach used to describe the featured deformation characteristic of cylindrical envelope is proposed by combining shear Hooke’s law with strain energy density. The analysis of total potential energy, including potential energy of supporting mechanism and strain energy in envelope, reveals a clear bistable state where both the fully collapsed and fully deployed states exhibit lower energy. An energy barrier existed between these two equilibrium states indicates that the capsule is “easy deploy and hard collapse.” Finally, the dynamics model is built by Lagrange equation and the bistable characteristic is verified by numerical simulation. General theory and method can be summarized as important theoretical foundation for design and implementation of the IEC.