Title: Auxetic metamaterials from disordered networks

Abstract

Recent theoretical work suggests that systematic pruning of disordered networks consisting of nodes connected by springs can lead to materials that exhibit a host of unusual mechanical properties. In particular, global properties such as Poisson's ratio or local responses related to deformation can be precisely altered. Tunable mechanical responses would be useful in areas ranging from impact mitigation to robotics and, more generally, for creation of metamaterials with engineered properties. However, experimental attempts to create auxetic materials based on pruningbased theoretical ideas have not been successful. In this study, we introduce a more realistic model of the networks, which incorporates angle-bending forces and the appropriate experimental boundary conditions. A sequential pruning strategy of select bonds in this model is then devised and implemented that enables engineering of specific mechanical behaviors upon deformation, both in the linear and in the nonlinear regimes. In particular, it is shown that Poisson's ratio can be tuned to arbitrary values. The model and concepts discussed here are validated by preparing physical realizations of the networks designed in this manner, which are produced by laser cutting 2D sheets and are found to behave as predicted. Furthermore, by relying on optimization algorithms, we exploit the networks' susceptibilitymore » to tuning to design networks that possess a distribution of stiffer and more compliant bonds and whose auxetic behavior is even greater than that of homogeneous networks. Finally, taken together, the findings reported here serve to establish that pruned networks represent a promising platform for the creation of unique mechanical metamaterials.« less

Authors:

Reid, Daniel R. ^[1]; Pashine, Nidhi ^[1]; Wozniak, Justin M. ^[2]; Jaeger, Heinrich M. ^[1]; Liu, Andrea J. ^[3]; Nagel, Sidney R. ^[1]; de Pablo, Juan J. ^[4]

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+ Show Author Affiliations

1. Univ. of Chicago, IL (United States)
2. Argonne National Lab. (ANL), Lemont, IL (United States)
3. Univ. of Pennsylvania, Philadelphia, PA (United States)
4. Univ. of Chicago, IL (United States); Argonne National Lab. (ANL), Lemont, IL (United States)

Publication Date:

2018-01-30

Research Org.:

Argonne National Laboratory (ANL), Argonne, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; University of Chicago - Materials Research Science & Engineering Center (MRSEC); National Institute of Standards and Technology (NIST) - Center for Hierarchical Materials Design (CHiMaD)

OSTI Identifier:

1498500

Grant/Contract Number:  

AC02-06CH11357

Resource Type:

Accepted Manuscript

Journal Name:

Proceedings of the National Academy of Sciences of the United States of America

Additional Journal Information:

Journal Volume: 115; Journal Issue: 7; Journal ID: ISSN 0027-8424

Publisher:

National Academy of Sciences, Washington, DC (United States)

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; auxetic; impact mitigation; metamaterials; optimization; structure