Prof. Yuji Sano Profile

Prof. Yuji Sano

Professor at Institute for Molecular Science

SPIE Involvement:

Conference Chair | Author | Editor

Proceedings Article | 11 April 2024 Presentation + Paper

New advancements for laser-matter interaction applied to laser shock peening

A. Rondepierre, Y. Rouchausse, L. Videau, R. Fabbro, O. Casagrande, Y. Sano, O. Castelnau, L. Berthe

Proceedings Volume 12939, 129390K (2024) https://doi.org/10.1117/12.3006086

KEYWORDS: Plasma, Pulsed laser operation, Laser applications, Metals, Water, Laser development, Thermal modeling, Laser-matter interactions, Laser irradiation, Laser energy

Read Abstract +

Proceedings Article | 21 December 2022 Presentation

Improvement of residual stress on metal surface and fatigue properties by laser peening with microchip laser mounted on robotic arm

Yoshio Mizuta, Satoshi Tamaki, Kiyotaka Masaki, Tomoharu Kato, Yoshihiro Sakino, Tomonao Hosokai, Yuji Sano

Proceedings Volume 12312, 123120H (2022) https://doi.org/10.1117/12.2644048

KEYWORDS: Robotics, Metals, Pulsed laser operation, Laser development, High power lasers, Corrosion, Stress analysis, Molecular bridges, Fluctuations and noise, Bridges

Read Abstract +

Proceedings Article | 11 October 2021 Presentation

Improvement of residual stress and fatigue properties of high-strength steel by low-pulse energy microchip laser

Yoshio Mizuta, Yuji Sano, Satoshi Tamaki, Yoshihiro Sagisaka, Tomoharu Kato, Yoshihiro Sakino, Tomonao Hosokai

Proceedings Volume 11892, 118920Q (2021) https://doi.org/10.1117/12.2602732

KEYWORDS: Pulsed laser operation, Laser energy, Corrosion, Molecular bridges, Light sources, Laser systems engineering, High power lasers, Fluctuations and noise, Bridges

Proceedings Article | 8 March 2019 Open Access

Quarter Century Development of Laser Peening and Recent Strides toward Expansion of Applications

Yuji Sano

Proceedings Volume 10911, 1091102 (2019) https://doi.org/10.1117/12.2517039

Read Abstract +

Proceedings Article | 8 September 2006 Paper

Development and applications of laser peening without coating as a surface enhancement technology

Yuji Sano, Naruhiko Mukai, Masaki Yoda, Takuya Uehara, Itaru Chida, Minoru Obata

Proceedings Volume 6343, 634324 (2006) https://doi.org/10.1117/12.707937

KEYWORDS: Coating, Optical fibers, Fiber lasers, Pulsed laser operation, Laser applications, Nd:YAG lasers, Corrosion, Head, X-rays, Control systems

Read Abstract +

Proceedings Article | 7 February 2000 Paper

Process and application of shock compression by nanosecond pulses of frequency-doubled Nd:YAG laser

Yuji Sano, Motohiko Kimura, Naruhiko Mukai, Masaki Yoda, Minoru Obata, Tatsuki Ogisu

Proceedings Volume 3888, (2000) https://doi.org/10.1117/12.377033

KEYWORDS: Laser irradiation, Plasma, Wave propagation, Pulsed laser operation, Laser processing, Metals, Nd:YAG lasers, Head, Fiber lasers, Laser systems engineering

Read Abstract +

The authors have developed a new process of laser-induced shock compression to introduce a residual compressive stress on material surface, which is effective for prevention of stress corrosion cracking (SCC) and enhancement of fatigue strength of metal materials. The process developed is unique and beneficial. It requires no pre-conditioning for the surface, whereas the conventional process requires that the so-called sacrificial layer is made to protect the surface from damage. The new process can be freely applied to water- immersed components, since it uses water-penetrable green light of a frequency-doubled Nd:YAG laser. The process developed has the potential to open up new high-power laser applications in manufacturing and maintenance technologies. The laser-induced shock compression process (LSP) can be used to improve a residual stress field from tensile to compressive. In order to understand the physics and optimize the process, the propagation of a shock wave generated by the impulse of laser irradiation and the dynamic response of the material were analyzed by time-dependent elasto-plastic calculations with a finite element program using laser-induced plasma pressure as an external load. The analysis shows that a permanent strain and a residual compressive stress remain after the passage of the shock wave with amplitude exceeding the yield strength of the material. A practical system materializing the LSP was designed, manufactured, and tested to confirm the applicability to core components of light water reactors (LWRs). The system accesses the target component and remotely irradiates laser pulses to the heat affected zone (HAZ) along weld lines. Various functional tests were conducted using a full-scale mockup facility, in which remote maintenance work in a reactor vessel could be simulated. The results showed that the system remotely accessed the target weld lines and successfully introduced a residual compressive stress. After sufficient training for operational personnel, the system was applied to the core shroud of an existing nuclear power plant.