Superior mechanical properties by exploiting size-effects and multiscale interactions in hierarchically architected foams

TL;DR

This paper demonstrates how hierarchical design and size effects in architected VACNT foams can synergistically enhance mechanical properties like strength, modulus, and energy absorption, surpassing traditional trade-offs for protective applications.

Contribution

It introduces a full-factorial DOE approach to optimize multiscale parameters in VACNT foams, breaking conventional scaling laws and achieving unprecedented property enhancements.

Findings

Synergistic improvement in SEA, strength, and modulus in VACNT foams.

Size effects and hierarchical interactions enable breaking diameter-to-thickness scaling laws.

Optimized design parameters lead to superior mechanical performance for extreme environments.

Abstract

Protective applications in extreme environments demand thermally stable materials with superior modulus, strength, and specific energy absorption (SEA) at lightweight. However, these properties typically have a trade-off. Hierarchically architected materials--such as the architected vertically aligned carbon nanotube (VACNT) foams--offer the potential to overcome these trade-offs to achieve synergistic enhancement in mechanical properties. Here, we adopt a full-factorial design of experiments (DOE) approach to optimize multitier design parameters to achieve synergistic enhancement in SEA, strength, and modulus at lightweight in VACNT foams with mesoscale cylindrical architecture. We exploit the size effects from geometrically-confined synthesis and the highly interactive morphology of CNTs to enable higher-order design parameter interactions that intriguingly break the diameter-to-thickness (D/t)-dependent scaling laws found in common tubular architected materials. We show that exploiting complementary hierarchical mechanisms in architected material design can lead to unprecedented synergistic enhancement of mechanical properties and performance desirable for extreme protective applications.