Wednesday  |  Allegheny  |  11:50 AM–12:10 PM

#13398, High Strain-Rate Compression Behavior of Polymeric Kelvin Lattice Structures

The compressive high strain-rate behavior of polymeric Kelvin lattice structures with rod-based or plate-based unit cells was investigated through experimental techniques and finite element simulations. Polymeric lattice structures with 5x5x5 unit cell geometries were additively manufactured using Digital Light Processing (DLP) vat polymerization and tested at low (~0.001/s) and high (~1000/s) strain-rates. High strain-rate experiments were performed with a viscoelastic split-Hopkinson (Kolsky) pressure bar system (SHPB) using experimental dispersion and attenuation corrections. Force equilibrium was achieved for forces as low as 400 N to 3 kN for the lattice specimens. Digital image correlation (DIC) on high-speed images (100,000 fps) was used on SHPB interfaces to validate experimental results and showed good agreement with SHPB measurements. Both low and high strain-rate experiments reveal the formation of a localized deformation band in lattice specimens, which was more prevalent in low relative density specimens and low strain-rate experiments. Results show that failure properties and energy absorption depended strongly on the relative density of the lattice specimen and exhibited distinct scaling between relative density and geometry type (rod, plate) at both loading rates. Low relative density plate-lattices demonstrated superior mechanical properties to rod-lattices--for a given mechanical property there exists a critical relative density (17%-28%) below which plate-lattices outperform rod-lattices of similar mass. High strain-rate finite element simulations were performed using Abaqus/Explicit and showed good agreement with the deformation modes and failure trends observed in the experiments.

John Weeks   Caltech
Guruswami Ravichandran   Caltech