早稲田大学 · 工学
Hosoi教授の研究室では、高周波疲労や超高サイクル疲労にまで及ぶ複合材料の損傷挙動を解明するとともに、疲労亀裂の電気的修復技術の開発を進めています。特に、ステンレス鋼やCFRP（炭素繊維強化プラスチック）における亀裂の発生・拡大挙動を高精度な非破壊評価と電気脈動処理を用いて定量的に解析しています。長寿命構造の信頼性向上を目的とした、材料の疲労挙動と修復メカニズムの解明が主な研究テーマです。
Figures are computed from collected data and may differ slightly.
A technique to heal a fatigue crack in austenitic stainless steel SUS316 by applying a controlled, high-density pulsed current was developed. A surface-activated pre-coating (SAPC), which eliminates the oxide layer and coats a Ni film on the crack surface, was used to improve the adhesion between crack surfaces. Cracks were observed by scanning electron microscopy before and after the application of high-density electropulsing. To evaluate the healing effect of the SAPC during crack propagation,
High-cycle fatigue characteristics of quasi-isotropic carbon fiber reinforced plastic (CFRP) laminates [−45/0/45/90]s up to 108 cycles were investigated. To assess the fatigue behavior in the high-cycle region, fatigue tests were conducted at a frequency of 100 Hz, since it is difficult to investigate the fatigue characteristics in high-cycle at 5 Hz. Then, the damage behavior of the specimen was observed with a microscope, soft X-ray photography and a 3D ultrasonic inspection system. In this st
Carbon fiber reinforced plastic (CFRP) laminates are used as main structural members in many applications. Transverse cracks that form in 90° layers of CFRP laminates are mostly initial damage in the case where tensile loading is vertically applied to the 90° layers of CFRP laminates, and they are the origin of more serious damage of delamination and fiber breakage. It is thus important to predict quantitatively the transverse crack initiation of CFRP laminates subjected to cyclic loadin
It is time-consuming to conduct conventional hydraulic fatigue testing up to the very-high cycle fatigue (VHCF, N (number of cycles) ≥ 10 8 ) regime. Ultrasonic fatigue testing has been proposed as an accelerated alternative method. In this study, ultrasonic fatigue testing was conducted on interlaminar toughened quasi-isotropic carbon-fiber reinforced plastic (CFRP) laminates to evaluate the characteristics and mechanism of fatigue up to the VHCF regime. Hydraulic fatigue tests were conducted a
ABSTRACT Fatigue cracks were healed by controlling a high‐density electric current. The changes in the displacement distribution around the crack tip and the stress intensity factor before and after crack healing were evaluated quantitatively with a digital image collation method. According to the results, it was determined that the cracks were closed by approximately 2 to 7 µm in this study. On the other hand, the stress intensity factor decreased or increased depending on the conditions of the
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