Mechanical engineers at the University of Wisconsin–Madison, in the leadership of Associate Professor Ramathasan Thevamaran, have unveiled a novel design framework that streamlines the creation of shock-absorbing materials with precise custom performance—without increasing weight or overall volume, reports their College of Engineering website. This marks a notable departure from traditional design, which typically targets foams that maintain a stress plateau in their stress–strain response. In that approach, designers iteratively tweak the material’s intrinsic properties, often disregarding the actual foam pad geometry (thickness and cross-sectional area) in the application context.
The University of Wisconsin team’s framework alters that design paradigm by integrating both material behavior and geometric constraints. Through a dimensional analysis-guided methodology, they established relationships among stress–strain characteristics, pad thickness, and area, resulting in algebraic guidelines for designing compact, lightweight foams that still meet impact protection requirements.
Their research demonstrates a counterintuitive but powerful insight: foams exhibiting nonlinear stress–strain responses (i.e., lacking the traditional constant-stress plateau) can outperform conventional plateau-behavior materials in scenarios with strict size or weight constraints. The framework enables designers to identify the optimal stress–strain profile and geometric configuration that minimizes thickness and mass while absorbing a target kinetic energy.
For validation, the team applied their design rules to architected hierarchical vertically aligned carbon nanotube (VACNT) foams, optimizing them for real-world energy-absorbing applications. This versatile, geometry-aware methodology provides mechanical engineers with a streamlined path to tailor advanced shock-absorbing materials, ideal for lightweight protective systems in automotive, aerospace, sports, or military applications.