Ultralight and ultra-stiff nano-cardboard panels: mechanical analysis, characterization, and design principles

TL;DR

This paper presents the design, computational analysis, and microfabrication of ultra-light, ultra-stiff nano-cardboard panels with honeycomb cores, demonstrating their superior mechanical properties and scalable manufacturing for advanced applications.

Contribution

It introduces a novel honeycomb-core nano-panel design with optimized stiffness and a scalable microfabrication process validated by experimental testing.

Findings

Panels have over five orders of magnitude higher bending stiffness than solid plates of same area density.

Computational models accurately predict the mechanical behavior of the fabricated panels.

Microfabrication enables rapid production of large, lightweight panels with precise control over properties.

Abstract

We introduce a class of ultra-light and ultra-stiff sandwich panels designed for use in photophoretic levitation applications and investigate their mechanical behavior using both computational analyses and micro-mechanical testing. The sandwich panels consist of two face sheets connected with a core that consists of hollow cylindrical ligaments arranged in a honeycomb-based hexagonal pattern. Computational modeling shows that the panels have superior bending stiffness and buckling resistance compared to similar panels with a basketweave core, and that their behavior is well described by Uflyand-Mindlin plate theory. By optimizing the ratio of the face sheet thickness to the ligament wall thickness, panels maybe obtained that have a bending stiffness that is more than five orders of magnitude larger than that of a solid plate with the same area density. Using a scalable microfabrication process, we demonstrate that panels as large as 3x3 cm^2 with a density of 20 kg/m^3 can be made in a few hours. Micro-mechanical testing of the panels is performed by deflecting microfabricated cantilevered panels using a nanoindenter. The experimentally measured bending stiffness of the cantilevered panels is in very good agreement with the computational results, demonstrating exquisite control over the dimensions, form, and properties of the microfabricated panels.