Vol. 8 No. 2 CONTENTS

Review Paper (Vol.8 No.2)

Sensing with Carbon Fibres in Polymer Composites

Karl SCHULTE

43

General Papers (Vol.8 No.2)

Fatigue Properties of Notched Aluminum Specimens after Hard Rolling

Xuelan L. YUE, Shin-ichi NISHIDA and Nobusuke HATTORI

53

Influence of Na2Si2O5 on the Hydration of Tetracalcium Aluminoferrite

Kwang SUK YOU, Hirotaka FUJIMORI, Koji IOKU and Seishi GOTO

60

Influence of Na2Si2O5 on the Hydration of C4AF with Various Surface Areas

Kwang Suk YOU, Hirotaka FUJIMORI, Koji IOKU and Seishi GOTO

64

Performance of Calcium Silicate Hydrate Briquettes Produced from Fly Ash and Slaked Lime in Disposal of Wastewater

Yasushi HIRASHIMA, Toshihiro MORIGA, Toshifumi ASHIDA, Eiji KANEZAKI and Ichiro NAKABAYASHI

68

Application of X-Ray Stress Measuring Technique to Curved Surfaces -Residual Stress on Spherical Surfaces-

Taizo OGURI, Kazuo MURATA, Katusmi MIZUTANI and Kenjiro UEGAMI

74

Short comunications (Vol.8 No.2)

A Numerical Investigation on Variation of Shape Parameter in Two-Parameter Weibull Distribution Function Fitted to Distribution of Ceramic Strength

Toshihiko HOSHIDE and Junko ABE

82

Second-Harmonic Generation in Thermally/Electrically Poled Transparent BaTiO3 Thin Films Prepared by Dip-Coating Method

Iwao SAKAIHARA, Katsuhisa TANAKA, Takashi WAKASUGI, Rikuo OTA, Yoshinori YONESAKI and Kazuyuki HIRAO

85


Vol.8 No.2 ABSTRACT


Sensing with Carbon Fibres in Polymer Composites

Karl SCHULTE

Abstract:Carbon-fibre-reinforced polymer (CFRP) composites derive their excellent mechanical strength, stiffness and electrical conductivity from carbon fibres. The mechanical deformation and electrical resistance are coupled in these fibres that make them inherently sensors. Thus CFRPs can be considered as a self-monitoring material without any need for additional sensing elements. However, for this to become reality the conductivity map of the entire structure needs to be constructed and the relationships between the conductivity and various use- and damage-related variables need to be established. Experimental results demonstrate that internal damage, such as fibre fracture and delamination, decreases the conductivity of composite laminates. In general, the information about the damage size and position can be obtained by utilising electrical impedance tomography (EIT).

Key Words:Health monitoring, Electrical conductivity, CFRPs, Electrical impedance tomography, Non-destructive testing


Fatigue Properties of Notched Aluminum Specimens after Hard Rolling

Xuelan L. YUE, Shin-ichi NISHIDA and Nobusuke HATTORI

Abstract:Research results of the application of hard-rolling treatment to aluminum surface odification are presented. The main objective of the research presented here was to study the change in fatigue properties, particularly fatigue crack behavior of notched aluminum specimens after hard rolling. The results indicated an obvious improvement in fatigue properties of the luminum specimens after hard rolling, but the extent of enhancement of fatigue strength was nearly the same or even decreased slightly with the increase of the hard-rolling value. Fatigue crack initiation and propagation behavior displayed different characteristics for specimens with different hard-rolling values. The microstructural change and the appearance of compressive residual stress at the notch were employed to explain the effect of hard rolling on the fatigue properties of aluminum. In addition, a saturation condition was observed in the compressive residual stress introduced by hard rolling. This phenomenon was explained in terms of the intrinsic properties of the material studied in this work.

Key Words:Aluminum, Fatigue properties, Hard rolling, Notched specimen, Microstructural change, Compressive residual stress, Work hardening


Influence of Na2Si2O5 on the Hydration of Tetracalcium Aluminoferrite

Kwang SUK YOU, Hirotaka FUJIMORI, Koji IOKU and Seishi GOTO

Abstract:The hydration of C4AF was retarded by the addition of Na2Si2O5 of up to approximately 0.1mass% and the hydration completely stopped when it exceeded 0.1 mass%. Metastable phases, such as Ca2Al(OH)7・3H2O and Ca2Al2O5・8H2O, etc., were produced when C4AF was hydrated in Na2Si2O5 solution, whereas hydrogarnet was formed as the main hydration product when C4AF was hydrated in water. The ion concentrations of Ca and Al in the liquid phase decreased, and at the same time the period for hydrogarnet formation in the paste was delayed with an increase in the amount of Na2Si2O5 added to the liquid phase.

Key Words:Hydration reaction, Tetracalcium Aluminoferrite, Sodium Silicate, Hydrogarnet, Retardation, Solubility


Influence of Na2Si2O5 on the Hydration of C4AF with Various Surface Areas

Kwang Suk YOU, Hirotaka FUJIMORI, Koji IOKU and Seishi GOTO

Abstract:The hydration of C4AF having various surface areas was investigated with Na2Si2O5 solution. The hydra-tion behavior of C4AF depended on the amount of silicate ions precipitated on its surface. The amount of precipitated silicate ions, which hindered the hydration of C4AF, was proportional to the surface area of C4AF. The precipitated silicate ions on the surface of C4AF were founded to be a silica-like material by means of X-ray photoelectron spec-troscopy (XPS). They formed a layer approximately 3 nm thick on the surface of C4AF.

Key Words:Hydration reaction, Ferrite phase, Sodium silicate, Retardation, Silica layer, Surface area


Performance of Calcium Silicate Hydrate Briquettes Produced from Fly Ash and Slaked Lime in Disposal of Wastewater

Yasushi HIRASHIMA, Toshihiro MORIGA, Toshifumi ASHIDA, Eiji KANEZAKI and Ichiro NAKABAYASHI

Abstract:Hydrothermal reaction of fly ash and slaked lime produces a porous briquette which is composed of amorphous calcium silicate, a tobermorite-like compound and hydrogarnet. It is essential for the molar ratio (cal-cium oxide)/(silicon dioxide) of the briquette to be 0.3 to achieve high performance in the purification of waste-water through improved microorganism-carrying ability. The chemical oxygen demand (CODMn) index in artifi-cial, non-fecal drainage decreases more rapidly with the use of the briquettes than that without the briquettes. The macroscopic configuration of the briquettes is an important factor in the water-purification ability, although the high specific surface area of the briquettes does not affect the performance. By increasing the circulation flow rate of the wastewater, the purification performance is improved considerably.

Key Words:Ceramics, Microporous materials, Surface properties, Calcium Silicate Hydrate, Wastewater


Application of X-Ray Stress Measuring Technique to Curved Surfaces -Residual Stress on Spherical Surfaces-

Taizo OGURI, Kazuo MURATA, Katusmi MIZUTANI and Kenjiro UEGAMI

Abstract:When the sin2Ψ method is applied to the residual stress measurement of a curved surface, a large-sized X-ray irradiation area causes some errors in the residual stress measured. However, it is difficult to set a sufficiently small irradiation area to a curved surface with a small radius of curvature when the diffraction intensity is weak or the sizes of grains are large. In this study, the focus is put on a spherical surface, and the relation between the residual stress measured and the size of the X-ray irradiation area is investigated experimentally and analytically. Tangential residual stresses of steel-balls used in ball-bearings were measured for various sizes of the X-ray irradiation areas. Numerical analyses simulating the X-ray stress measurement were performed under various conditions: materials, characteristic X-rays and values of the stress. It is found that the geometric effect appears in the gradient of the 2θ-sin2Ψ diagram chiefly and that the non-linearity in the 2θ-sin2Ψ relation owing to the geometric effect is not so remarkable. As a result, we have shown a threshold of the geometric effect as a reference standard by a ratio of the irradiation size to the diameter of the sphere, and have proposed a practical formula estimating the actual circumferential stress on the spherical surface from the tangential stress measured and the geometric factors: the diameter of the sphere, the size of the X-ray irradiation area, and the thickness of the masking plate.

Key Words:X-ray stress measurement, Curved surface, Spherical surface, Ball-bearing, Steel-ball, Residual stress, sin2Ψ method, Nondestructive inspection