As materials and engineering design tools become more complex, engineers are looking to mimic structures and systems which occur in nature in order 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 behaviour of the tail structure of the virus has been simplified by neglecting the intermolecular mechanisms which actuate the bistable behaviour of the tail. This behaviour has been achieved through the use of prestressed composite flanges which are mechanically joined together 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 in order to enhance its potential applications in the aerospace industry.

This work proposes a mechanism for replicating the inter-molecular behaviour 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 behaviour is obtained by replacing mechanical fasteners in the traditional lattice structure in select locations with a series of permanent magnets and electromagnets. Finite element analysis is used in order 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 tuneable curved actuator with potential applications in satellite dish actuation, for example.

 

References

\[1\]      A. Pirrera, X. Lachenal, S. Daynes, P. M. Weaver, and I. V. Chenchiah, “Multi-stable cylindrical lattices,” *J. Mech. Phys. Solids*, vol. 61, no. 11, pp. 2087–2107, 2013.

\[2\]      C. McHale, R. Telford, and P. M. Weaver, “Compact Multistable Telescopic Lattice Boom,” in *The ASME 2019 Conference on Smart Materials, Adaptive Structures and Intelligent Systems*, 2019.

 


Reconfigurable Multi-Stable Helical Lattice

Division / Sponsors: 
Aerospace Division

Paper Proceedings: https://asmedigitalcollection.asme.org/SMASIS/SMASIS2020/volume/84027

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