Jamming With 3D Printers at the University of Chicago

No, not the guitar-playing jamming…  In the world of material science, “jamming” is what occurs when the volume available to a bunch of grains in a granular material (such as sand) gets so small that the grains jam into each other, effectively getting stuck. Depending on the shape of the grains, the material will display different characteristics such as strength, flexibility and friction. Got it? Moving on…

Heinrich Jaeger is a Professor of Physics at the University of Chicago. He runs a laboratory for investigating experimental condensed matter. Several of their projects involved showing how granular jamming could be put to practical use – two video highlights include the JamBot and the Universal Jamming Gripper.Prof. Jaeger and his students want to learn what the ideal shapes are for these randomly packed grains or particles for the characteristic(s) that they want to optimize. Traditionally, they would explore different shapes based on their previous experience. In the past, they were essentially limited to shapes that they could find and/or have “armies” of graduate students prepare by hand.But three years ago, Professor Jaeger began working with one of his graduate students, Marc Z. Miskin – and 3D printing – to study “jamming” and the structural properties of shapes. They developed a computer algorithm that approached the problem in a completely different way. Rather than starting with a particular shape and then evaluating its properties, their breakthrough algorithm would take a defined goal or set of parameters and then “search” through the space of possible shapes to provide a recommended shape. This algorithm produces many unexpected solutions and complex shapes since it is not based on any human experience or bias.

Cheaper, Faster, and More Complex

The use of 3D printing became essential for their research with this algorithm. Producing thousands of irregularly shaped particles by hand became all but impossible. However, it would be relatively straight forward to produce a 3D model of the desired particles and then quickly print them on a sophisticated 3D Printer.  In addition to saving time and money, the 3D printed particles would also have the additional benefit of being more precisely shaped than those produced manually.  The research team could then perform physical experiments and testing on sets of particles whose shapes were “invented” by the computer algorithm.

As a result, Professor Jaeger’s lab became the first lab on the University of Chicago campus to have a 3D Printer.  The printer they chose was a Stratasys Objet Connex350 multi-material 3D Printer. According to Professor Jaeger, they chose the Objet Connex350 for several clear reasons:

• Multi-material capabilities (allowing for particles with multiple properties)
• Digital mixing of materials (creating unique materials)
• Great resolution

In fact, Professor Jaeger gets very excited when he proclaims that “Both the range of materials and the digital mixing of materials are fantastic!”When I ask Professor Jaeger what his biggest surprises were as they started 3D printing with the Connex line of 3D Printers, he mentions several. First of all, the 3D Printers are very fast and reliable. He was very (happily) surprised at how quickly they could 3D print batches of 10,000 particles. They can leave the 3D Printers to work unattended overnight and then just come in and clean off the particles in the morning. Also, Jaeger said, the software that accompanies the Objet Connex 3D Printers is very good and easy to use.

Looking Ahead

What is next for Prof. Jaeger and his students in their use of 3D printing? He says that there is still a lot to be done in this area of finding the strongest shapes. They are working to invent the next wave in this field of Granular Matter and he expects that the ability to mix multiple materials digitally will play an increasingly major role.

He also said he sees 3D printing expanding into other areas of his lab, such as creating prototypes, creating specific pieces and parts (such as specialized brackets and holders), and 3D printing other objects needed for their research.

All we can say is keep on jamming Prof. Jaeger!