Researchers at the University of Chicago are using 3D printed shapes to analyze how the properties of a “jammed” material can be tuned by changing the shape of the constituent particles.
“Jamming” is a process whereby granular materials become stiffer when the particle density increases, basically they transition from a fluid-like to solid-like behavior. These particles can be regular spheres or more complicated shapes, or even molecules. Jamming is relevant in areas such as robotic hands, where a rubber gripper is filled with a granular material that conforms to the shape of an object when inflated, and when the air is removed the material goes solid and “grips” the object.
The purpose of the research in Prof. Henrich Jaeger’s lab at the university is to analyze how the properties of a jammed material can be altered by changing the shape of the constituent particles.
A computer algorithm is used to design the particles, which starts from a random shape, and then iteratively altered and tested in a computer simulation. After computer testing many different shape variations an optimal shape is then sent to the 3D printer where a large number are printed.
The “particles” are put in a confined space then tested under force in a press to see if their performance matches the algorithm’s predictions. See it in action below: