Abstract
Design of shock absorbers requires a delicate balance between mechanical properties and geometric design, allowing them to be compressible yet strong enough to withstand crushing loads. Here, we present a unified framework for designing compact and lightweight shock absorbers by employing a streamlined kinematic model and dimensional analysis. We derive geometric constraints on the thickness and cross-sectional area of a protective foam with a given stress-strain response to ensure that acceleration and compressive strain remain within critical limits. Additionally, we identify the optimal mechanical properties that yield the most compact and lightweight protective foam pads for absorbing impact energy. Contrary to common belief, we demonstrate that foams with a nonlinear stress-strain response can effectively achieve thin and lightweight protective pads, particularly when a large cross-sectional area is required. Guided by this design framework, we introduce optimal architected designs of vertically aligned carbon nanotube (VACNT) foams—a low-density hierarchical material system.
| Original language | English |
|---|---|
| Article number | 7148 |
| Journal | Nature Communications |
| Volume | 16 |
| Issue number | 1 |
| DOIs | |
| State | Published - Dec 2025 |
| Externally published | Yes |
Funding
This research is supported by the U.S. Office of Naval Research under PANTHER program (grant number N000142112044, awarded to R.T.) through Dr. Timothy Bentley, as well as by the solid mechanics program of the U.S. Army Research Office (grant number W911NF2010160, awarded to R.T.) through Dr. Denise Ford. The authors acknowledge the use of facilities and instrumentation at the Wisconsin Centers for Nanoscale Technology (WCNT), partially supported by the NSF through the University of Wisconsin Materials Research Science and Engineering Center (DMR-1720415). We also acknowledge Team Wendy for their Zorbium soft and hard polyurethane foams, which were compared with our VACNT foams for mechanical performance.