Ultra-dissipative Foams and Liners to Prevent Concussions Using Liquid-Crystal Elastomers

Peter E. Jenkins, Amir H. Torbati, Christopher M. Yakacki
University of Colorado Denver, Colorado, United States

Keywords: Energy Absorbing Materials, Shock Absorption, Dissipation, Liquid Crystal

We propose using liquid-crystalline elastomers (LCEs) to mimic the natural organization of soft tissues, create novel dissipative liner foams, and to overcome the existing challenges of impact absorption in current materials used in helmets. LCEs are unique in their ability to dissipate energy during a collision. Their behavior is attributed to liquid-crystal order, which can be hierarchical similar to natural tissues. We have characterized and compared the dissipation behavior of natural tissues and synthetic polymers over a wide range of frequencies. Our results demonstrate that LCE materials can match the dissipative behavior of spinal tissues such as the intervertebral disc, which is the body's essential shock absorber. Therefore, we hypothesize that LCEs can be utilized to design the next generation of protective helmet liners that replicate the functionality of biological tissues by mimicking its hierarchical structure, inherent dissipative properties, and anisotropic (i.e. directionally dependent) behavior. This work is inspired by nature, as the woodpecker has a tongue (tissue) that wraps around its brain and prevents concussions. Our lab is working to design LCE-foams to substitute into military and athletic helmets and test the performance of the improved helmets according to ASTM and NOCSAE standards.