3D Printing and Simulation to Design Affordable Prosthetic Arms
While 3D printing technology has been around for more than 25 years, the recent arrival of affordable desktop 3D printers means that large companies and R&D groups are no longer the only ones with access to this powerful technology. Students, hobbyists, and makers are getting involved and using their talents to change the world.
Making an Impact on Prosthetic Arms Accessibility
One area where 3D printing has enjoyed major impact is medical prosthetics. In general, the cost of a prosthetic limb ranges anywhere from $15,000 – $90,000 and must be replaced every 3-4 years due to the wear and tear of everyday use . For children, these costs are compounded as they are growing and need to be fitted with a new prosthesis more regularly. Conversely, “a 3D printed prosthetic arm costs less than a reel of plastic, so about $40,” says Will Davies, a volunteer with e-NABLE—a web-based community that brings together volunteers from around the world who use their 3D printers, design skills, and personal time to create free 3D printed prosthetic arms and hands for children who need them .
Will and his father Bruce—a retired biochemist—, have been involved with e-NABLE since 2013 and 2014, respectively, and have used their 3D printer to produce prosthetic arms for 22 children in their home country—the United States. The process is straightforward, explains Will, “All of the designs are open source so all you need to do is buy the plastic, 3D print the arm, clean up the print, put it together with the hardware, and then customize the fit for the child.”
The child must have a functional wrist or elbow to operate e-NABLE devices properly. The prosthetic hands open and close using the flexing of the wrist or elbow to create tension so that a fist can be made. This allows the child to grasp a pencil, hold sports equipment, or balance better on a bicycle.
Using SimScale to Improve the Design
Will and Bruce have been working on the RIT arm, which is an adaptive device designed for those with an elbow but no wrist. They noticed that this particular arm design had a tendency to break around the same point, at the location where the extension comes off of the elbow cup. Turning to SimScale, “I was able to determine where the maximum stresses and strains were, and we then worked to add reinforcements to those weak areas,” says Will.
The RIT arm (left) and the extension cup piece (geometry, mesh, stress) shown in SimScale
By thickening the plastic at the location of high stress and increasing the size of the fillet, Will and Bruce have created a working model which feels much stronger; however, it hasn’t yet been “battle-tested.” We look forward to hearing about the results!
Want to learn more about simulation with SimScale? Download this booklet.