Design and Experimentation of Additively Manufactured Hierarchical Architected Lattices for Energy Absorption
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Date
2020-05
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The Ohio State University
Abstract
Energy absorption structures are critical components in many engineering applications, such as sport equipment and transportation crashworthiness. Conventional energy absorption structures such as foams and lattices have demonstrated their effectiveness and strengths, however, they lack the significant design degrees of freedom that 3D hierarchical architected lattices possess. This research aims at expanding the design domain of energy absorption lattices, and aids future work in design optimization of energy absorption lattices.
This research investigates the energy absorption capabilities of 3D hierarchical architected lattices. Hierarchical lattices are structures composed of self-similar or different architected metamaterials across multiple length-scales. Hierarchical architected lattices have superior properties when compared to conventional homogeneous materials; and opens the door for a wide range of material property manipulation and optimization.
The effect of introducing a hierarchy to a lattice on the energy absorption performance is demonstrated. In addition, the effect of relative density on the energy-absorption was isolated by creating a comparison between a 1st order Octet lattice that has the same relative density as a 2nd order Octet lattice. The effect of changing the 2nd order unit cell geometry from an Octet, Dodecahedron, to Truncated Octahedron is studied. The results will establish a series of trends related to energy-absorption capacity, volumetric energy-absorption efficiency, load, and strain applied. The effect of changing the cross-sectional geometry of the trusses with respect to energy-absorption performance is investigated. Changing the orientation of the 2nd order cells has a considerable effect on the force displacement-curve, and the energy-absorption performance of the lattice. An analytical solution for the 1st order and the 2nd order Octet lattices is discussed to the validate the force-displacement results obtained from the finite element analysis. In addition, in order to compare the force-displacement behavior of the 1st and the 2nd order Octet lattices, an experimental compression test mimicking the finite element analysis boundary conditions was conducted. The findings and the provided comprehension of this research will aid the future work in optimization of energy-absorption architected lattices.