Ultrasonic properties of fly ash/polyurea composites

Abstract

An experimental study has been conducted to determine the mechanical properties of fly-ash/polyurea composites by measuring their longitudinal and shear wave velocities, and attenuations at various fly ash volume fractions, using ultrasonic.The complex-valued longitudinal and shear moduli were computed from these measurements at various temperatures. It was observed that a 30% volume fraction addition of fly ash has increased the longitudinal storage and loss moduli and shear storage and loss moduli by up to 22%, 141%, 298% and 125%, respectively. The complex bulk modulus and Poisson's ratio of the composites at 1MHz were also estimated. Additionally, a computational model based on the method of dilute-randomly-distributed inclusions was created to estimate the dynamic mechanical properties of the composites. The experimental and computational results were compared and showed good agreement.

Atomic-scale simulation of hugoniot relations and energy dissipation of polyurea under high-speed shock

“…Owing to the thermodynamic incompatibility of soft and hard segments as well as the hydrogen bonds between urea groups, the hard segments aggregate and form rod-shaped hard domains, which are surrounded by the soft matrix formed by the soft segments, resulting in the micro-phase separation phenomenon (Castagna et al, 2012;Das et al, 2007;Li et al, 2018). The mechanical and chemical properties of polyurea are also distinctive such as temperature sensitivity (Guo et al, 2016;Jia et al, 2016;Qiao et al, 2011;Qiao et al, 2016), pressure sensitivity (Amirkhizi et al, 2006), strain rate sensitivity (Joshi and Milby, 2012;Sarva et al, 2007;Shim and Mohr, 2009;Yi et al, 2006) and frequency sensitivity (Jia et al, 2016;Qiao et al, 2011;Qiao et al, 2016). Polyurea also has moisture and corrosion resistance and is easy to spray.…”