Papers by Keyword: Area Fraction

Abstract: With the recent trend of down-sizing and more efficient use of electric power in electric appliances, there is a growing need of smaller electronic components, such as multi-layered ceramic capacitors (MLCCs). However, it was found that the non-uniform deformation occurred in MLCC block during the pressing process and it hinders the miniaturization of MLCCs. In this study, compression tests of multi-layered ceramic sheets with printed electrodes were carried out and the deformation behavior was observed in situ and recorded by digital video camera. The change in area fraction and transverse displacement were evaluated and the deformation mechanism was inferred from the results.

Abstract: A three-phase composite circle model is presented in this paper to assess the effect of interfacial transition zone (ITZ) on the chloride diffusion coefficient of concrete. Firstly, the distribution of circular aggregate particles was simulated in a square concrete element. Based on the simulated concrete mesostructure, the Monte Carlo algorithm was adopted to numerically evaluate the ITZ area fraction for different concrete mixes. A parametric study was then conducted to quantify the effects of the largest aggregate diameter, ITZ thickness and aggregate gradation on the ITZ area fraction. Secondly, the ITZ was modeled as a thin-wall annular plate located between a circular aggregate particle and a thick-wall cement paste annular plate. With the three-phase composite circle model, an analytical solution was derived for the chloride diffusion coefficient of concrete. Finally, the derived solution was verified by experimental results obtained from the research literature and a quantitative relationship between the thickness and chloride diffusion coefficient of ITZ was established.

Abstract: In this study, the creep-fatigue crack growth behavior was investigated at 600°C under the maximum load with various dwell times. Test material was P92 steel (9%Cr-2%W) weldment. The creep-fatigue crack growth behavior of the HAZ(heat affected zone) and base metal was compared. The relationship between the crack growth behavior and dwell time was studied and it was characterized using ΔK and (Ct)avg parameters. The area fraction of micro-voids/cavities at the crack tip and fracture modes were examined and the relationship between crack growth rate and dwell time was investigated. The cycle dependant crack growth rate increased with the increase in dwell time. From the results of creep-fatigue test, the crack growth rate of the HAZ was found to be faster than that of base metal. As the dwell period increased, the intergranular fracture was observed along the crack growth path with the effect of creep during the dwell period.