Mechanical Characteristics of Bistable Inflatable Folding Beam Structure

Folding structures are easy to transport and deploy, and they have promising engineering applications. A multi-stable folding system with a high deployment efficiency can be obtained by combining the inflatability of pneumatic structures with the multi-stability of origami structures. With the triangular unit as the basic element, an inflatable-driven folding beam structure with folding and unfolding bistable characteristics was designed, and then the mechanical characteristics of the designed beam were analyzed through the finite element method. The results showed that after the designed beam was inflated, the maximum stress appeared at the intersection of multiple creases between adjacent cavities, and with the increase in the fluid cavity pressure, the increase rate of the crease stress was four times that of inner wall stress. It was easier to break the energy barrier of the bistable state by applying a longitudinal load perpendicular to the crease direction of the design beam than by applying the transverse load along the crease direction. Therefore, when the designed beam was subjected to bending deformation, its bearing capacity was not significantly affected by the change of the fluid cavity pressure. However, when the designed beam was compressed under a longitudinal load, the fluid cavity pressure increased by 10Formula: see textkPa, and the longitudinal load-bearing capacity was increased by about 12.8%. Finally, increasing an inner angle of a triangle within the limits will enhance the load capacity of the design beam. It is difficult to improve the proposed beam load capacity by increasing the sheet width.