Momentum - The Magazine for Virginia Tech Mechanical Engineering Vol. 4 No. 4 Winter 2019 | Page 9

09 Because the mechanical design of the chiton’s girdle scales had not been studied in-depth before, the team of researchers needed to start with basic material and mechanical analysis with the mollusk before using that information as the bio-inspiration for the engineering research. “We studied this biological material in a very detailed way. We quantified its internal micro- structure, chemical composition, nano-mechanical properties, and three-dimensional geometry. We studied the geometrical variations of the scales across multiple chiton species, and we also investigated how the scales assemble together through 3D tomography analysis,” Li said. The team then developed a parametric 3D modeling methodology to mimic the geometry of individual scales. They assembled individual scale units on either flat or curved substrates, where the scales’ sizes, orientations, and geometries can also be varied, and used 3D printing to fabricate the bio-inspired scale armor models. “We produced the chiton scale-inspired scale assembly directly with 3D multi-material print- ing, which consists of very rigid scales on top of a flexible substrate,” Li explained. With these physical prototypes of controlled specimen geometries and sizes, the team conducted direct mechanical testing on them with controlled loading conditions. This allowed the researchers to understand the mechanisms behind the dual protection-flexibility performance of the biological armor system. PhD students Ting Yang and Zhiefei Deng pose with Assistant Professor Ling Li and several 3D printed examples of the armor they created.