By Caleb Sooknanan ’20

Compliant mechanisms are mechanisms that can transfer forces or displacements to other points along their bodies. 3D printing can be used to quickly and effectively design compliant mechanisms for commercial use, but more work is needed to understand how such devices can be printed. Doctor Bernhard Thomaszewski and researchers from Disney Research Zurich in Switzerland devised a computational tool that would allow users to create flexible versions of rigid devices. The computational system was created to address design challenges such as geometry irregularities, possibilities of material fatigue or failure, and a lack of parameters for specific motions.

The researchers first modeled compliant mechanisms as a series of rigid links, or elements would that provide stiff connections between sections of a model. These links would include a set of flexures or layers modeled using elastic rods, along with joints that allowed parts to rotate within a model. Flexure orientations would allow models to be connected to an input driver, such as a motor, from which the model would communicate signals throughout its structure. Mathematical equations were used to simulate desired parameter values that would optimize the mechanisms’ functions, such as motor tracking, stability, and closeness to a target configuration.

The researchers tested their computational tool’s effectiveness with Jansen’s linkage, a leg mechanism used to simulate smooth walking motions. A model’s conventional hinges were replaced with compliant flexures to replicate the function of the original mechanism. A remote-controlled car, an eyeball mechanism, a compliant hand, and a dragon were also designed to test eye motion quality, steering, operated grasping, and spatial wing mechanisms, respectively.

The results for each design showed that material failure prevention would allow compliant mechanisms to operate more effectively. Notable limitations of this study include how stable behavior, instead of dynamic behavior, formed the primary focus of the design. More research is needed to understand how compliant mechanisms can address dynamic behavior within their respective designs. Nevertheless, the researchers successfully demonstrated that flexible models could be designed with refined computational means.

References:

1. B. Thomaszewski, et al., A computational design tool for compliant mechanisms. Association for Computing Machinery Transactions on Graphics 36, (2017). doi: 10.1145/3072959.3073636
2. Image retrieved from: https://www.3dprintingbusiness.directory/news/wp-content/uploads/2017/07/A-Computational-Design-Tool-for-Compliant-Mechanisms-Image-e1501083547383.jpg