Abstract

As materials and engineering design tools become more complex, engineers are looking to mimic structures and systems, occurring in nature, to design more efficient mechanical structures. One such structure is a morphing composite lattice structure, whose design was inspired by the tail of the bacteriophage T4 virus [1]. To date the morphing behavior of the tail structure of the virus has been simplified by neglecting the intermolecular mechanisms that actuate the bistable behavior of the tail. This behavior has been achieved using prestressed composite flanges that are mechanically joined in alternating clockwise and anti-clockwise chiralities. The composite lattice structure has previously been proposed as an actuator for aerospace structures, replacing more complex and heavier traditional actuator structures. McHale et al. [2] have shown that the composite lattice is capable of greatly improving upon the state-of-the-art in the form of a telescopic boom for CubeSat systems. This utility provides validity in studying further enhancements on the capabilities of the structure to enhance its potential applications in the aerospace industry.

This work proposes a mechanism for replicating the inter-molecular behavior that occurs in the bacteriophage T4 tail. The bonds between the inner and outer tail structures are broken and reformed, thus, driving the actuation process. This method will form a variable topology morphing system. As such, a novel category of morphing structure is presented here for the first time. The morphing topology behavior is proposed by replacing mechanical fasteners in the traditional lattice structure in select locations with a series of permanent magnets. Finite element analysis is used to calculate the difference in energies between the states before and after discrete topology changes occur, allowing the associated change in energy to be converted to a required actuation force. Varying the topology of the lattice structure allows the lattice to transition from a linear morphing actuator system to a bespoke and tunable curved actuator with potential applications in satellite dish actuation, for example.

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