Novel Material Systems for Infrastructure and Structural Protection
US National Science Foundation
Tong Hui and Caglar Oskay
Work and Objectives
Polyurea layered woven glass fiber reinforced epoxy matrix composite structures subject to blast
Determine blast mitigation effects of polyurea to the woven composite structure
Design microstructures to optimize blast mitigation effects
Multiscale modeling of wave propagation in composite structures
Use the high order homogenization model to reduce computational expense
Investigate wave dispersion and energy dissipation in periodic composite structures
Explain distinguishing dynamic phenomena of periodic composites, e.g. phononic bandgap
Introduction and Motivation
Polyurea layers have been recently shown to drastically improve the blast response of steel structures. By understanding the deformation mechanisms associated with the high-strain rate response of polyurea-steel composite structures, it will be possible to design infrastructure systems with superior blast protection.
When the length of a group of traveling waves and the size of the material microstructure are comparable, the waveform interacts with the microstructure through reflections and refractions (i.e., dispersion) at the interfaces of constituent materials. Distinct material properties occur when the wave dispersion is strong.
Blast mitigation of polyurea layer to composite structures
In this investigation, a woven glass fiber reinforced epoxy matrix composite structure subject to blast is considered. Polyurea is layered with the composite structure. The damage and deformation in the composite structure and are analyzed and used to quantify blast mitigation effects of the polyurea layer.
Case:1 GFRD + Polyurea
Wave propagation in periodic composite structures
High order homogenization modeling of wave propagation in periodic composite structures
A new high order homogenization model for modeling dispersion in
periodic composite structures
The model can interrogate the full range of impedance contrast for microstructure-induced dispersion.
Standard C0 continuity finite elements are used to capture the micro-inertia effects.
Phononic bands, e.g. frequency bands within which micro-inertia effects block wave propagation are predicted.
One dimensional wave propagation
In one-dimensional wave propagation, cyclic loadings with different frequencies are imparted in a bi-material bar. Wave dispersion and energy dissipation due to the viscoleastic phase in the structure are examined.
Strong wave dispersion reveals bandgap in the periodic structure, and occurrence of the bandgap can be changed by altering microstructural configurations (volume ratio of phase-1 = 0.1, 0.4, 0.6, 0.9 respectively).
Multi-dimensional wave propagation
Shear wave in 2-D layered composite structures
A cyclic shear wave is imparted from the top of a layered composite structure.
The wave is propagating in the vertical direction and vibrating in the horizontal direction.
Structural bandgap occurs when the wave length is close to the microstructural size.