Developable Compliant Rolling-Contact Element (D-CORE)

A CORE, or compliant rolling-contact element, is composed of two cams joined together with multiple complaint flexures. Tension develops in these flexures as the cams roll in contact with another; this holds the cams together. This motion allows the CORE to mimic the rotation of a pin joint. The developable CORE, or D-CORE, allows this CORE joint to be manufactured from a single sheet and stored in a compact position. Some advantages a D-CORE might have over the traditional pin joint include decrease in friction and wear, the mitigation of backlash, decreased cost of manufacturing, and decreased weight and possibly size. The most sizable difference between the motion of a D-CORE versus a pin joint is the axis of rotation. When a D-CORE rolls, its axis of rotation is moving. The movement of this axis of rotation is calculable but not dismissible; therefore, if an application requires a fixed axis of rotation, the use of a CORE mechanism will likely be impractical.

Assembly

Note: If needed, add a small amount of super glue onto each tab before inserting them into their proper places as shown. This will help secure each flexure while the D-CORE is in use.

Applications

The CORE joint has shown promise in multiple biomedical engineering applications including orthopedic joint replacements and brace designs.
The figure below shows a modified CORE design presented as an option for spinal disc replacements. This design achieves a healthy quality of motion for lumbar replacement as well as decreased wear compared to other replacement options.

Alexander Henry Slocum, a previous student at Massachusetts Institute of Technology, also used the principles of this CORE mechanism to develop knee and hip replacements, as well as a more advanced joint for a knee brace.
The D-CORE’s ability to store compactly also could have many advantages when it comes to space-constrained applications. These applications include minimally invasive surgeries, medical implants, aerospace technology, and even household furniture.

Learn More

This design was developed by the Compliant Mechanisms Research Group (CMR) from Brigham Young University (BYU). Follow us at @byucmr on Instagram, @CompliantMechanismsResearchGroup on Facebook, or visit the BYU Compliant Mechanisms Research (CMR) website to learn more about compliant mechanisms.

Technical Information

For in-depth technical information, see the following publications:

Halverson, P. A., Bowden, A. E., & Howell, L. L. (2012). A compliant-mechanism approach to achieving specific quality of motion in a lumbar total disc replacement. International Journal of Spine Surgery, 6(1), 78-86.

Nelson, T. G., & Herder, J. L. (2018). Developable compliant-aided rolling-contact mechanisms. Mechanism and Machine Theory, 126, 225-242.

Nelson, T. G., Lang, R. J., Magleby, S. P., & Howell, L. L. (2016). Curved-folding-inspired deployable compliant rolling-contact element (D-CORE). Mechanism and Machine Theory, 96, 225-238.

Halverson, P. A., Howell, L. L., & Magleby, S. P. (2010). Tension-based multi-stable compliant rolling-contact elements. Mechanism and Machine Theory, 45(2), 147-156.

To learn more about compliant mechanisms in general, see the BYU Compliant Mechanisms Research (CMR) website or these books: Compliant Mechanisms, Handbook of Compliant Mechanisms.

Patents

Slocum, A. H., & Massachusetts Institute of Technology. (2013). Rolling contact orthopaedic joint design

“Deployable Joint,” Howell, L.L., and Nelson, T.G., U.S. Patent 10,227,804, issued March 12, 2019. “Spinal Implant,” Halverson, P.A., Howell, L.L., Magleby, S.P., and Bowden, A.E., U.S. Patent 8,308,801, November 13, 2012.

Intellectual Property

The downloadable 3D print files provided here may be used, modified, and enjoyed for noncommercial use. To license this technology for commercial applications, contact:

BYU Technology Transfer Office
3760 Harold B. Lee Library
Brigham Young University
Provo, UT 84602
Phone: (801) 422-6266
https://techtransfer.byu.edu/contact