Density-Graded Foams and Lattice Structures for Structural and Biomedical A

Graded Foams and Lattice Structures for Biomedical and Structural Applications

Load-bearing and energy absorption mechanisms in cellular solids depend strongly on their hierarchical structures. Designing cellular materials and lattice structures for energy mitigating applications requires an in-depth understanding of how the structural components behave under dynamic loading conditions at multiple length-scales. Our research seeks to pursue the idea of correlating mesoscale material properties and structural hierarchy in architectured materials to their macroscale energy absorption response. Light-weight structures with applications in biomedical research are of particular interest in our group.

One of our research thrusts focuses on identifying optimal density gradients that provide superior load-bearing and impact-energy-mitigation capabilities while maintaining low structural mass. We are currently interested in the design, development, and optimization of density-graded hexagonal honeycomb structures subjected to in-plane (left) and out-of-plane (right) loading.

Functionally graded cellular materials (FGCM) have recently attracted tremendous attention in impact mitigation applications due to their high specific strength and the ability to be tailored for various needs, from sports gear to automotive industries. Fabricating highly flexible interface layers with low mechanical impedance and improved adherence to their adjacent layers reduces the propensity of interfacial failure in FGCMs under impact. We utilize both conventional and advanced manufacturing techniques to fabricate graded cellular structures with interfaces optimized for enhanced energy absorption performance. These graded structures are tested in controlled conditions. Through multiscale in situ and ex situ measurements, we identify the principal deformation and failure mechanisms in these structures.

Our main objective is to develop process-structure-performance maps that correlate gradation functions and cellular structures with energy absorption performance for a number of different applications.

The graphic on the right shows an example of the concept of tailored interface incorporated in protective helmets. Graded cellular laminates are used to broaden the shock width, δ, and reduce its kinetic energy.

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