Multi-Scale Progressive Failure Mechanism and Mechanical Properties of Nanofibrous Polyurea Aerogels
Abstract
The nonlinear mechanical properties, deformation and failure mechanisms of polyurea aerogels (PUAs) were investigated using a multi-scale approach that combines nanoindentation, analytical and computational modeling. The atomistic structure of primary particles of PUAs and their mechanical interactions were investigated with molecular dynamics simulations. From nanoindentation we identified four deformation and failure modes: free ligament buckling, cell ligament bending, stable cell collapsing, and ligament crush induced strain hardening. The corresponding structural evolution during indentation and strain hardening were analyzed and modeled. The material scaling properties were found to be dependent on both the relative density and the secondary particle size of PUAs. Using a porosity-dependent material constitutive model, a linear relationship was found between the strain hardening index and secondary particle size instead the conventional power-law relationship. Finally, the structural efficiency of PUAs with respect to the capability for energy absorption is evaluated as a function of structural parameters and base polymeric material properties.
Recommended Citation
C. Wu et al., "Multi-Scale Progressive Failure Mechanism and Mechanical Properties of Nanofibrous Polyurea Aerogels," Soft Matter, vol. 14, no. 38, pp. 7801 - 7808, Royal Society of Chemistry, Aug 2018.
The definitive version is available at https://doi.org/10.1039/C8SM01546E
Department(s)
Civil, Architectural and Environmental Engineering
Second Department
Chemistry
Research Center/Lab(s)
Center for High Performance Computing Research
Keywords and Phrases
Aerogels; Biomechanics; Deformation; Mechanical properties; Molecular dynamics; Nanoindentation; Outages; Particle size; Strain hardening; Structural properties, Deformation and failure mechanism; Deformation and failures; Material constitutive models; Mechanical interactions; Molecular dynamics simulations; Multi-scale approaches; Nonlinear mechanical properties; Structural efficiencies, Failure (mechanical)
International Standard Serial Number (ISSN)
1744-683X; 1744-6848
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2018 Royal Society of Chemistry, All rights reserved.
Publication Date
01 Aug 2018
Comments
Financial support for this study was provided by National Science Foundation under Award No. CMMI-1030399 and the ARO under Award No. W911NF-14-1-0369.