Analytical Planar Design of Multiaxial Rigid Load-Bearing Tendon-Constrained Inflatables

Abstract

Deployable load-bearing structures are useful for confined or temporary settings due to their stowability and deployability. Designing these structures involves balancing package dimensions with load-bearing capacity—defined as the maximum load under which a structure can maintain rigidity or the load above which a structure deforms. This challenge is further complicated when considering load-bearing capacities in different directions. Tendon-constrained inflatables (TCIs) offer a promising solution with its design flexibility using internal tendon configurations. TCIs feature a deployable bladder held between rigid end caps which are connected internally by inextensible tendons. A TCI maintains rigidity up to its rigid load-bearing (RLB) capacity, at which some tendons become slack. The RLB capacities can be customized in different directions depending on the tendon configuration. This article introduces a model-based design approach of a TCI's tendon configuration to trade-off RLB capacities in different directions and against package dimensions. A 3D kineto-static equilibrium model is developed to relate tendon configuration to six-dimensional RLB capacities. Visual design strategies for planar tendon configurations guide the customization of TCIs to specific package dimensions and loading scenarios. Experimental validation of the model enables TCIs, an emerging adaptive structure, to be useful for a broad range of applications.