Montemayor, L. C. and Greer, J. R. (2015) Mechanical Response of Hollow Metallic Nanolattices: Combining Structural and Material Size Effects. Journal of Applied Mechanics, 82 (7). Art. No. 071012. ISSN 0021-8936. http://resolver.caltech.edu/CaltechAUTHORS:20150625-115224109
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Ordered cellular solids have higher compressive yield strength and stiffness compared to stochastic foams. The mechanical properties of cellular solids depend on their relative density and follow structural scaling laws. These scaling laws assume the mechanical properties of the constituent materials, like modulus and yield strength, to be constant and dictate that equivalent-density cellular solids made from the same material should have identical mechanical properties. We present the fabrication and mechanical properties of three-dimensional hollow gold nanolattices whose compressive responses demonstrate that strength and stiffness vary as a function of geometry and tube wall thickness. All nanolattices had octahedron geometry, a constant relative density, ρ ∼ 5%, a unit cell size of 5–20 μm, and a constant grain size in the Au film of 25–50 nm. Structural effects were explored by increasing the unit cell angle from 30 deg to 60 deg while keeping all other parameters constant; material size effects were probed by varying the tube wall thickness, t, from 200 nm to 635 nm, at a constant relative density and grain size. In situ uniaxial compression experiments revealed an order of magnitude increase in yield stress and modulus in nanolattices with greater lattice angles, and a 150% increase in the yield strength without a concomitant change in modulus in thicker-walled nanolattices for fixed lattice angles. These results imply that independent control of structural and material size effects enables tunability of mechanical properties of three-dimensional architected metamaterials and highlight the importance of material, geometric, and microstructural effects in small-scale mechanics.
|Additional Information:||© 2015 ASME. Manuscript received November 20, 2014; final manuscript received April 9, 2015; published online June 3, 2015. The authors gratefully acknowledge the financial support from the National Science Foundation through NSF Graduate Research Fellowship of L.C.M. and Grant Nos. of J.R.G. (CMMI-1234364 and DMR-1204864). The authors would like to acknowledge Professor Lorenzo Valdevit at the University of California Irvine for the analytic model used to determine the deformation mechanism of the fabricated samples. The authors also acknowledge the critical support and infrastructure provided by the Kavli Nanoscience Institute at Caltech. The authors would also like to thank Z. Aitken and D. Jang for their help in TEM sample preparation/analysis and L. Meza for SolidWorks images/discussion.|
|Group:||Kavli Nanoscience Institute|
|Subject Keywords:||cellular solids; hierarchical materials; size effect; metamaterials|
|Official Citation:||Montemayor, L. C., & Greer, J. R. (2015). Mechanical Response of Hollow Metallic Nanolattices: Combining Structural and Material Size Effects. Journal of Applied Mechanics, 82(7), 071012-071012. doi: 10.1115/1.4030361|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Jason Perez|
|Deposited On:||25 Jun 2015 23:16|
|Last Modified:||25 Jun 2015 23:16|
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