• Professor at the Advanced Institute for Materials Research, Tohoku University
• Ando Hiroyasu

• IHI Corporation

Forestation businesses that operate in Indonesia's tropical peatlands always need to keep the groundwater levels constant in order to cultivate forests and reduce carbon dioxide (CO₂) emissions. For the purpose of managing groundwater levels, we are developing technologies that estimate the levels based on measurement and observation data from tropical peatlands and operational simulations of water management, and aiming at contributing to society through such development.

• IHI Power Systems Co., Ltd.

IHI Power Systems Co., Ltd. has succeeded in significantly reducing carbon dioxide (CO₂) emissions compared with conventional ships by adopting the DC (direct current) voltage grid system for the series hybrid. The series hybrid uses electric motors for propulsion and a combination of batteries and generators for electricity.

• IHI Engineering Review Editorial Office

• Managing Executive Officer and General Manager of Corporate Research & Development Division IHI Corporation
• KUBOTA Nobuhiko

• SATO Hayao, HARUYAMA Daichi, KITAMURA Yoshiyuki, NAKAMURA Hiroshi, HONDA Tatsuhito

Ceramic matrix composites (CMC) have higher heat resistance and specific modulus than Ni-based alloys, thus they are desired to be more applied to aircraft engine parts such as turbine parts. As engine parts are exposed in the condition over the heat durability, multiple holes are generally made on them in order to cool their surface. However, there are few research results on small hole effect for CMC fatigue life. This study focused on this phenomenon. Fatigue tests were conducted using flat plates manufactured with a single hole and multiple holes. As a result of tests, different fracture and crack propagation modes were observed between single-holed and multiple-holed types. A life prediction model was considered to explain the life degradation. The strength parameters were calculated by averaging stress fields, which were predicted by finite element analysis (FEA), in area of CMC unit cell. By using the life prediction model developed in this study, fatigue lives of all types of test pieces with hole can be predicted based on the S-N curve obtained from a smooth-shaped test piece without hole.

• KITAMURA Yuta, TSUNORI Mitsuyoshi, YAMADA Takehisa, USHIDA Hirohisa

In aero engines, it is expected to improve the prediction accuracy of the disk burst rotation speed under overspeed condition and reduce the weight of the disk. In order to improve the prediction accuracy of disk burst by structural analysis, it is important to model the ultimate behavior of the material until fracture. In this study, the ultimate limit state evaluation leading to overspeed burst was carried out by structural analysis for a Ti-6Al-4V disk. The stress-strain relationship up to the high-strain region obtained by the digital image correlation method and the ductile fracture criterion based on the fracture strain dependent on stress state were used in this evaluation.

• MIYAZAWA Yuto, CHIBA Ryosuke, OTA Yutaro

Structural materials undergo various types of damage during use, which can lead to deterioration and failure. To prevent failure or recurrence, it is necessary to identify the causes of damage. However, in conventional damage investigations, estimations have been mostly based on the knowledge and experience of evaluators, leading to subjective and unstable results. It is expected to make generalized estimations, that are not dependent on knowledge or experience, by using machine learning image classification methods for microstructure images of damaged materials. This paper presents the prediction results of machine learning model, which accuracy was 89 % by using EBSD (Electron Backscatter Diffraction) images of three types of damaged materials (creep, creep-fatigue, fatigue). This result shows the potential for accurately estimating damage patterns through this method.