Yoshio Miyoshi

Evaluation of fatigue crack growth behavior of GLARE3 fiber/metal laminates using a compliance method

Abstract The objectives of this study were to investigate the effectiveness of a compliance method for analyzing the fatigue crack growth of GLARE3 fiber/metal laminates. The materials tested were GLARE3-5/4 (2.6 mm thick) and GLARE3-3/2 (1.4 mm thick). Centrally notched specimens with two kinds of notch length and two kinds of fiber orientation were fatigue tested under constant amplitude loading. The expression of the experimental stress intensity factor, K exp , for the 2024-T3 aluminum-alloy layers of a GLARE3 is formulated and K exp were obtained from the relationship between crack length and specimen compliance. The test results clarified the following: (1) d a /d N –Δ K exp relationships roughly show the linear relationship independent of the maximum stress level, specimen thickness, notch length, and fiber orientations, (2) the d a /d N –Δ K exp relationships approximately agree with the linear part and its extension of Paris–Erdogan’s law obtained for the d a /d N –Δ K relationship of the 2024-T3 aluminum-alloy, (3) the compliance method is effective for analyzing fatigue crack growth in GLARE3 laminates.

Difference-of-Gaussian-Like Characteristics for Optoelectronic Visual Sensor

Architecture using a new nonlinear optoelectronic sensor has been developed to imitate the functions of the higher level visual cortex. The optoelectronic sensor developed in this work has the properties approximated by difference of Gaussian (DOG) functions. The properties are due to the negative photoinduced current (PIC) and the negative differential (ND) characteristics according to the forward bias voltage, which have been successfully obtained for layer structures with a charge-storage layer of InAs/GaAs short-period superlattice. By using the new sensors, an optoelectronic sensing circuit has been designed conceptually to imitate the functions of selectivity to orientation angle, motion-direction and length of slit light in visual cortex.

Charge-storage-type optoelectronic sensor with DOG-function characteristics

The optoelectronic sensors with DOG (difference of Gaussian)-function characteristics have been developed successfully for the application to the artificial visual cortex. The remarkable negative photoinduced current (PIC) and negative differential (ND) characteristics according to the forward bias voltage have been obtained for GaAs/GaAlAs multi-quantum well (MQW) structures with a charge-storage layer of InAs/GaAs short period superlattice (SSL). The characteristics are dependent on the crystal quality of the charge-storage layer and extremely enhanced by using the InAs/GaAs SSL compared with InGaAs alloy. In addition, we have designed an optoelectronic sensing circuit to mimic the mechanism of the selectivity to orientation, motion-direction and length of slit light in a human visual cortex

Effect of Sputtering Gas Pressure and Bias Voltage on Mechanical Properties of TiN Coating Deposited by DC Magnetron Sputtering

The mechanical properties of TiN films deposited on carbon steel JIS S45C by reactive dc magnetron sputtering under three sputtering gas pressures, 0.5Pa, 0.8Pa, and 1.76Pa were investigated. The residual stress once increased and then decreased with increasing bias voltage at 0.5Pa and 0.8Pa, but increased monotonously at 1.76Pa. These variations could be explained by the variations of the bombarding energy of a sputtered ion at each gas pressure. The variations of hardness and toughness correlated with the variation of residual stress. The variation of adhesive strength also could be explained by the variation of the bombarding energy with a model proposed in this study. A specific wear rate was also investigated, and it was found that to increase not only the hardness but also the adhesive strength is necessary to improve the wear resistance of TiN films.Copyright

Evaluation of Fatigue Damage in Coarse-Grained Aluminum With Scanning X-Ray Energy Dispersive Diffraction Microscope

Based on the Berg-Barrett method, Scanning Energy Dispersive X-ray Diffraction Microscopy (SEDXDM) has been developed for nondestructively evaluating both the surface and subsurface of poly-crystallized materials. The SEDXDM includes an X-ray source generating continuous X-ray spectrum as a key component to form a highly resolved 2-D horizontal cross-sectional digital image. This article presents the evaluation of the fatigue damage (e.g., slip line and slip band caused by fatigue deformation) of the coarse-grained aluminum, which is made by means of annealing and has been repeatedly bent to generate the stress and make the slope of the stress created in the thickness direction of the plate specimen, under fully reversed anti-plane bending condition with the SEDXDM.© 2004 ASME