Abstract

Liquid crystal elastomers (LCEs) exhibit unique mechanical properties of soft elasticity and enhanced energy dissipation with rate dependency. They are potentially transformative materials for applications in mechanical impact mitigation and vibration isolation. However, previous studies have primarily focused on the mechanics of LCEs under equilibrium and quasistatic loading conditions. Critical knowledge gaps exist in understanding their rate-dependent behaviors, which are a complex mixture of traditional network viscoelasticity and the soft elastic behaviors with changes in the mesogen orientation and order parameter. Together, these inelastic mechanisms lead to unusual rate-dependent energy absorption responses of LCEs. In this work, we developed a viscoelastic constitutive theory for monodomain nematic LCEs to investigate how multiple underlying sources of inelasticity manifest in the rate-dependent and dissipative behaviors of monodomain LCEs. Here, the theoretical modeling framework combines the neo-classical network theory with evolution rules for the mesogen orientation and order parameter with conventional viscoelasticity. The model is calibrated with uniaxial tension and compression data spanning six decades of strain rates. The established 3D constitutive model enables general loading predictions taking the initial mesogen orientation and order parameter as inputs. Additionally, parametric studies were performed to further understand the rate dependence of monodomain LCEs in relation tomore » their energy absorption characteristics. Based on the parametric studies, particularly loading scenarios are identified as conditions where LCEs outperform conventional elastomers regarding energy absorption.« less

Authors:

Chung, Christopher ^[1]; Luo, Chaoqian ^[1]; Yakacki, Christopher M. ^[1]; Song, Bo ^[2]; Long, Kevin Nicholas ^[2]; Yu, Kai ^[1]

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+ Show Author Affiliations

1. Univ. of Colorado, Denver, CO (United States)
2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

Publication Date:

Fri Feb 09 00:00:00 EST 2024

Research Org.:

Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA); USDOE Laboratory Directed Research and Development (LDRD) Program; National Science Foundation (NSF)

OSTI Identifier:

2311611

Alternate Identifier(s):

OSTI ID: 2316080

Report Number(s):

SAND-2024-01619J
Journal ID: ISSN 0020-7683

Grant/Contract Number:  

NA0003525; CMMI-2046611

Resource Type:

Accepted Manuscript

Journal Name:

International Journal of Solids and Structures

Additional Journal Information:

Journal Volume: 292; Journal Issue: 1; Journal ID: ISSN 0020-7683

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

42 ENGINEERING; mesogen rotation; nematic director; mesogen order parameter; liquid crystal elastomers; viscoelasticity; energy dissipation; constitutive modeling