Session: 03-20-01: Manufacturing: General

Paper Number: 144983

144983 - Additive Manufacturing of Nematic Liquid Crystal Elastomer Foams for Dynamic Energy Dissipation 

Nematic liquid crystal elastomers (LCEs) are a unique material that possess inherent anisotropic properties resulting from the macroscopic alignment of their polymer backbone. LCEs are most commonly used as actuators in soft robotics applications due to their two-way shape memory response to external stimuli. Nonetheless, these same properties also give LCEs a unique soft elasticity, making them an ideal candidate for energy dissipation. New advances in additive manufacturing (AM) processes have enabled simple fabrication of dissipative structures with complex, cellular geometries. Here, we present the use of direct ink write (DIW) 3D printing, an extrusion AM approach, to prepare porous nematic LCE structures which can be used for multi-level mechanical damping. These structures can not only perform well in quasi-static environments as a result of their cellular architecture but also harness the dynamic energy dissipation properties of the LCE. We demonstrate that cellular architectures can dissipate energy in quasi-static environments with performance comparable to traditional elastomeric structures yet can provide dramatically improved dissipation in dynamic environments. These results present a promising pathway for the simple fabrication of multi-level damping devices.

 

Applying DIW manufacturing techniques allowed us to produce cellular nematic LCE architecture that had not yet been evaluated in other research for their dampening capabilities. Previous LCE research has been evaluated using either unaligned LCE or without cellular architectures; both of which fail to capture the full extent of LCE material properties and the AM design space. The nematic LCE structure's performance was tested in static, quasi-static, and dynamic environments through compression testing, impact testing, and high-frequency vibration testing respectively. The preliminary results show that LCE structures displayed fewer natural frequencies which lead to a decrease in energy transfer throughout dynamic environments and a quicker return to steady state under quasi-static loading.

 

LCE structures outperformed identical geometries produced using other elastomer materials in all three tested areas, leading us to conclude that LCE has improved mechanical damping properties that can be combined with dampening architecture to maximize mechanical dampening of multiple loading types. The next step in the research will be to enable digital light processing (DLP) manufacturing processes to produce nematic LCE more easily to expand the design space beyond the limitations of DIW. This will also allow increased tailoring of individual layers of printed material within geometric structures to focus damping for the desired static, quasi-static, or dynamic loading which will increase the efficiency with which energy will be dissipated.

 

Presenting Author: Adam Bischoff Oregon State University

Presenting Author Biography: Adam Bischoff is a first year graduate researcher in the Versatile Additive Manufacturing Lab at Oregon State University (VAMOS). Prior to joining the VAMOS Lab, he completed his undergraduate in mechanical and manufacturing engineering from Oregon State University in 2022 and then worked in silicon manufacturing before returning to Oregon State to pursue a Ph.D. at the end of 2023.

His research interests include developing and improving additive manufacturing (AM) processes via optimization of process parameters and multi-material design to best take advantage of the vast AM design space. Additionally, he is interested in the manufacturing and application of smart/active materials such as shape memory polymers (SMP) and liquid crystal elastomers (LCE) for use in biomedical devices, soft robotics, and energy harvesting devices.

Authors:

Adam Bischoff Oregon State University
Devin Roach Oregon State University