Material Characterization Evaluation Research Articles

Anodized porous silicon based humidity sensor: evaluation of material characteristics and sensor performance of AU/PSIO2/AU

Anodized porous silicon based humidity sensor: evaluation of material characteristics and sensor performance of AU/PSIO2/AU

Evaluation of Material Characteristics and Structural Dynamic Properties of a Historical Church: The Case of 19th Century Bursa Derekoy Church (Ayia Paraskevi)

Derekoy (Ayia Paraskevi) Church, built by the Orthodox Greeks in Bursa, is one of the prominent monuments built in the 19th century. The structure, which lost its community with the population exchange (1923) between Turkey and Greece, has since then been out of service and a rapid deterioration process has begun. Analysis works are frequently implemented for this purpose and become crucial in Turkey, of which a large part is within the earthquake zone. However, the majority of the studies on the preservation of historical buildings are lacking in detailed material analysis and numerical methods. Conducting a series of material tests and numerical analyses for the structure provides more reliable and qualified interventions since they influence the decisions on the reinforcement and protection methods employed for historical buildings. For this purpose, the material characterizations of the mortar, plaster and stones used in the church were carried out by performing physical, chemical, mechanical, petrographic and mineralogical tests on samples taken from the church. Afterwards, mechanical tests of the walls and vibration tests were conducted to determine the dynamic behavior of the building. Based on the results obtained from the analyses, a series of intervention methods were proposed. It is understood that the flat-jack, shear and vibration tests are vital for determining the real structural behavior of the building. Furthermore, it is recommended that vibration tests are carried out on both the overall structure and individual walls to determine the dynamic behavior of similar structures where only outer walls remain standing.

Evaluation of Material Characteristics of Xylite – Part 1. Influence of Moisture Content on Some Mechanical Properties

The structure of xylite as lithotype of lignite indicates that it predominately originates from tree stems, from the family Taxodiaceae or Cupressaceae. Despite drastic changes in the long term process of its transformation, it retains some relevant properties of wood, nowadays applicable for specific products. The research examined the influence of moisture content and temperature on modulus of elasticity (MOE) and modulus of rupture (MOR) as well as shear strength and hardness. With decreasing of moisture content, the bending strength and stiffness of xylite increased and was best fitted by power regression model. The increasing of testing temperature from 20 °C to 80 °C had negative effect on stiffness and bending strength of xylite. The hardness was positively correlated with density of xylite, whereas shear strength had the opposite tendency.

Quantification of Creep Cavitation in Welded Joint and Evaluation of Material Characteristics of Simulated Heat-Affected Zone in X 20 CrMoV 12 1 Steel

X 20 CrMoV 12 1(DIN 17 175) steel has been used for components subjected to high temperature in power plants and chemical and petroleum industries. Therefore, extensive studies have been made on this steel. However, these studies focused mainly on the base metal, and few studies on the welded joint have been reported. Actually, a large number of failures have occurred at the welded joint, so there is increasing need to investigate the characteristics of X 20 CrMoV 12 1 weldment. In this study, the interrupted and creep rupture tests were carried out and quantification of the creep damage was attempted for the X 20 CrMoV 12 1 welded joint. The interrupted and creep rupture tests were performed at four conditions\M650-60, 600-100, 600-120, and 575-150(|SDC-MPa)\Mon the X 20 CrMoV 12 1 welded joint specimens, respectively. It was revealed from the experimental results that creep damage mechanism of a welded joint was mainly creep cavitation, and that the intensively damaged area by creep cavitations was the transition region from fine-grained heat-affected zone (HAZ) to unaffected base metal, namely intercritical HAZ. For both the interrupted and ruptured specimens, quantification of creep damage was attempted by evaluating cavitated area fraction, average diameter, and the number of cavities with creep life fraction. In addition, on the basis of the heat input during the welding, microstructure, microhardness, and grain size of the actual intercritical HAZ, simulated HAZ was made in order to evaluate its material properties. For the simulated HAZ specimens, tensile, charpy impact, and creep rupture tests were carried out. As a result, yield, tensile strength, and elongation of simulated HAZ were similar to those of base metal, respectively, and impact property of simulated HAZ was slightly above base metal. Also, it was found that creep strength of simulated HAZ was inferior to that of the base metal.

高温変形のコンピュータシミュレーション その４： 材料評価

高温変形のコンピュータシミュレーション その４： 材料評価