Tunable Mechanical Metamaterial with Constrained Negative Stiffness for Improved Quasi-Static and Dynamic Energy Dissipation

Journal Article · Tue Apr 09 00:00:00 EDT 2019 · Advanced Engineering Materials

DOI:https://doi.org/10.1002/adem.201900163· OSTI ID:1828127

Morris, Clinton ^[1]; Bekker, Logan ^[2]; Spadaccini, Christopher ^[2]; Haberman, Michael ^[3]; Seepersad, Carolyn ^[3]

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1. Palo Alto Research Center Incorporated, Palo Alto, CA (United States)
2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
3. Univ. of Texas, Austin, TX (United States)

This paper presents the computational design, fabrication, and experimental validation of a mechanical metamaterial in which the damping of the material is significantly increased without decreasing the stiffness by embedding a small volume fraction of negative stiffness (NS) inclusions within it. Unlike other systems that dissipate energy primarily through large‐amplitude deformation of nonlinear structures, this metamaterial dissipates energy by amplifying linear strains in the viscoelastic host material. By macroscopically tuning the pre‐strain of the metamaterial via mechanical loading, the embedded NS inclusions operate about a constrained buckling instability. When further macroscopic vibrational excitation is applied, the inclusions amplify the strains of the surrounding viscoelastic medium. This results in enhanced dissipation of mechanical energy when compared to voided or neat comparison media. Microstereolithography, an emerging high‐resolution additive manufacturing (AM) technology, is employed to fabricate the deeply subwavelength inclusions which ensures broadband damping behavior. The mechanically induced broadband energy dissipation and manufacturing approach further differentiate the metamaterial from other approaches that exploit resonances, large deformations, or non‐mechanical instabilities. The computational design, fabrication, and experimental evaluation reported is the first dynamic demonstration of such a mechanically tunable NS metamaterial, potentially enabling components with integrated structural and damping capabilities.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA); National Science Foundation (NSF); US Department of the Navy, Office of Naval Research (ONR)
• Grant/Contract Number: AC52-07NA27344; CMMI-1435548; N00014-13-1-0631; IM# 944586
• OSTI ID: 1828127
• Alternate ID(s): OSTI ID: 1505872
• Report Number(s): LLNL-JRNL-824979; 1022011
• Journal Information: Advanced Engineering Materials, Vol. 21, Issue 7; ISSN 1438-1656
• Publisher: Wiley
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
mechanical metamaterial
materials design
negative stiffness
microsterolithography