Papers by Keyword: Stiffening

Abstract: This study explored the stiffening behavior of the cement pastes using a new vibration folk technique. The viscosity evolutions of the cement pastes were evaluated using either a rotational viscometer or a tuning fork vibration viscometer. Results showed that the viscosities were increased with hydration time. The viscosity increases of the cement pastes measured by the vibro-viscometer were more stable than those measured by the rotational viscometer. In addition, the subtle changes in the paste viscosities during the very early hydration were well detected by the vibro-viscometer. The new vibration folk technique has been shown a useful tool to characterize the microstructure changes in the early cement pastes.

Abstract: Porous solids are less stiff than the solid, but its stiffness can be increased if the elastic properties of the struts within are sterically stiffened. The stiffening behavior cannot be modeled by conventional strain-based finite element method but can be modeled using couple stress mechanics. In this investigation, a new finite element modeling approach (FEM) based on strain field similitude is developed. The conventional displacement field was used to determine the steric rotation gradients and the additional high-order deformation energy. The mechanics basis underpinning the methodology and the conditions of applicability were detailed, and the results were benchmarked with analytical solution and experimental data. Finally, the methodology was applied to a periodic cellular structure to demonstrate the effect of steric stiffening in nanoporous solids.