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3D Printed armor inspired by mollusks

3D Printed armor inspired by mollusks

Ling Li, associate professor in the Department of Mechanical Engineering at Virginia Polytechnic Institute and State University (VT), conducted a study that created 3D printed flexible scaled armor inspired by chitons, a type of marine mollusk.

The goal of the research was to improve on the stiff structures utilized in man-made armors, which generally sacrifice flexibility and mobility. Thus, flexible, scaled ceramic armor components were produced utilizing parametric computational modeling and multi-material 3D printing.

“Most mollusks have a single rigid shell, such as the abalone, or two shells, such as clams,” explained Professor Li. “But the chiton has eight mineralized plates covering the top of the creature and around its base, it has a girdle of very small scales assembled like fish scales, that provide flexibility as well as protection.”

The chiton mollusk, which is about 1 to 2 inches long, has a series of eight large plates and is ringed by a girdle of smaller, more flexible scales. The mollusk is the inspiration behind a 3D printed armor. Image via Virginia Tech.
The 3D printed flexible armor inspired by the chiton mollusk on broken glass. Photo via Virginia Tech.

Hundreds of tiny, mineralized scales cover the soft girdle that surrounds the overlapping shell plates of the chiton species. According to the researchers, this provides flexibility for movement as well as protection for the underlying soft body, and thus is a good model for multifunctional armor construction. Furthermore, the authors noticed that chiton girdle scales had not been well examined previously to this investigation.

As a result, a parametric 3D modeling approach was created to replicate the geometry of individual scales. This was used to build individual scale units on flat or curved surfaces for additive manufacturing. Previously, VT scientists discovered a method for 3D printing piezoelectric materials, which transform mechanical energy into electric current.

Biological flexible scaled armor in the girdle of the chiton Rhyssoplax canariensis.
Three-dimensional geometry and surface morphology of individual dorsal scales of the chiton R. canariensis
Three-dimensional parametric modeling of chiton scale geometries.Design and fabrication of a bio-inspired flexible scaled armor. 

The rigidity of the 3D printed armor is derived from the scale arrangement, which has been highlighted further using computer modeling. This was supposed to show how, when the external load reached a certain value, the scale armor becomes interlocking and stiff. When it comes into touch with a force, the scales converge inward, forming a solid barrier.

It was also discovered that when the 3D printed scales were not subjected to force, they could slide on top of one another, providing varying degrees of flexibility depending on form and location. “With these physical prototypes of regulated specimen geometries and sizes, the researchers did direct mechanical testing on them with controlled loading conditions,” Professor Li continued.

Following these experiments, the researchers determined that the biological armor system’s dual protection-flexibility performance would be ideal for the manufacturing of 3D printed protective gear such as kneepads.

Bioinspired design of flexible armor based on chiton scales, Matthew Connors, Ting Yang, Ahmed Hosny, Zhifei Deng, Fatemeh Yazdandoost, Hajar Massaadi, Douglas Eernisse, Reza Mirzaeifar, Mason N. Dean, James C. Weaver, Christine Ortiz & Ling Li

Published: December 2019

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