Conceptual Design of a Shape-Adaptive Structure With Tailored Structural Instability

A particular set of requirements is identified for the response of a passively actuated shape-adaptive structure. It is shown that neither conventional structures nor simple structural instabilities have suitable properties in order to meet these requirements. A novel solution is proposed which combines multiple structural instabilities to create a compound instability. This approach enables the shape-adaptive structure to achieve large output displacements only after a triggering input displacement is reached. First, this approach is investigated via an analytical bar-and-spring model, before a parametric sensitivity study demonstrates how the structural response of the model can be ‘tuned’ by varying its governing parameters. Next, a representative candidate structure with an analogous mechanical response is presented, and governing structural parameters are identified. It is found that there is an equivalent governing parameter across both models, and that this parameter can be used to tune the response of candidate structure in a way which mirrors the response of the bar-and-spring model. This analogy allows the simple bar-and-spring model to inform the design of its more complex counterpart, which can then achieve the desired functionality of the morphing structure.