Mechatronic Materials and Systems. Design and Demonstration of High Aughtority Shape Morphing Structures

摘要

A concept for a high authority shape morphing plate is described and demonstrated. The design incorporates an active back-plane comprising a Kagome truss, capable of changing the shape of a solid face, connected to the back- plane by means of a tetrahedral truss core. The two shape deformations to be demonstrated consist of hinging and twisting. The design is performed by a combination of analytic estimation and numerical simulation, guided by previous assessments of the Kagome configuration. It is shown that, while the structure is capable of sustaining large passive loads at low weight, the demonstrable authority is actuator-limited. A protocol for optimizing is described. A first version assesses the required geometric dimensions and actuator specifications in order to maximize the permissible shape changes and load capacity. The critical external loads for all failure mechanisms of the individual components are calculated and used as constraints. The resistance of the structure to actuation is presented as an additional constraint. The ensuing relations are subsequently used to choose the best material for a given application. In a second version, the placement of the trusses to achieve the desired deformation, subject to the load capacity of the individual actuators, is ascertained. A two level scheme is used comprising a heuristic algorithm with a simplex-based optimization providing the cost function. It is shown that methods capable of avoiding entrapment in local minima, such as simulated annealing and genetic algorithm, give good results. The report is presented in three parts covering each of the important aspects of the design and implementation.