Keynote1: Yuji Sano (SANKEN, Osaka University / Institutes for Molecular Science)
Title: 30 Years Development of Laser Peening without Coating – System Miniaturization and Process Versatility
The author reviews the development of laser peening without coatings (LPwC) over the past 30 years in terms of system miniaturization through pulse energy reduction. The development of LPwC began in the early 1990s as an application of the copper vapor laser (CVL), the first high-power laser, visible-wavelength laser capable of penetrating water. By reducing the CVL pulse width from the original several tens of nanoseconds to less than 10 nanoseconds, surface compression was achieved without an ablative layer on the material. During this period, frequency-doubler using nonlinear crystals matured and CVLs were replaced by compact frequency-doubled Nd:YAG lasers. In 1999, LPwC with 200 mJ pulse energy was applied to reactor components to prevent stress corrosion cracking (SCC), and then expanded with fiber delivery technology of 100 mJ laser pulses. Recently, a finger-sized laser has been realized using monolithic microchip laser technology. Although the pulse energy is limited to 10 mJ, the pulse width is 1/10 of current Nd:YAG lasers and the peak power is maintained equivalent to that of 100 mJ laser pulses. LPwC using the finger-sized laser induced compressive residual stresses on the surfaces of aluminum alloys and high-strength steel. Fatigue properties were improved to the same level as those achieved with current Nd:YAG lasers.
Keynote2: Hyoung Seop Kim (POSTECH)
Title: Experiments and Modelling of Heterostructured Materials Processed by Ultrasonic Nanocrystalline Surface Modification
The advantages of heterostructured materials as structural materials include superior mechanical properties and the ability to tailor the strength-ductility combination via microstructure customization. To maximize heterostructure effects, we employed various processes, e.g., casting, severe plastic deformation, and additive manufacturing, combined with ultrasonic nanocrystalline surface modification processes to create multi-layered microstructured heterostructures. The fabricated materials have a novel microstructure composed of multiple layers of repetitive microstructures with heterogeneity and demonstrate a remarkable synergetic strengthening effect in comparison to conventional heterogeneous materials. The outstanding mechanical properties derived from various hard and soft layer interfaces, as well as the effects of each layer and interface, were quantitatively analyzed using grain-scale digital image correlation technology. The multi-layered microstructure with multiple heterogeneous boundaries breaks the conventional wisdom regarding heterostructured materials having only one or two heterogeneous interfaces. Constitutive modeling implemented into the finite element method was demonstrated.
Keynote3: Domenico Furfari (Airbus Operations GmbH)
Title: The use of Lights for Structural Performance Enhancement of Metallic Airframes. LEOPARDTM, a Laser Shock Peening industrial solution for Maintenance Repair Overhaul Use
The use of surface technologies inducing residual stresses can be employed in aeronautical industry as technologies to ensure salvage for identified hot spots in terms of fatigue and crack growth performance. Technologies and methodologies that improve the resistance of structures to in-service degradation processes such as fatigue are of benefit to the aircraft industry in terms of extending the service life of the structure and thus reducing maintenance costs. Laser Shock Peening (LSP) is a surface technology which introduces deep residual compressive stresses into a metallic structure aiming at improving the economical and ecological impact of an aging fleet as well as of future aircraft structures by controlling the residual stresses. A newly developed low energy portable equipment (Airbus IP) for MRO deployment capable of LSP in fully assembly aircraft while at repair station will be presented. The LEOPARD™ (Laser Equipment for Operations of Peening in Aircraft Retrofit Deployment), first around the world laser peening portable equipment receiving ATEX (Atmosphere Explosive Environment) certification for CLASS IV laser, will be described in detail. Current LSP systems are not compatible with commercial aircraft maintenance environments. Rigid and complex mirror-based beam delivery systems may be a showstopper for applying LSP treatment at fatigue critical components for in-service commercial aircraft during standard maintenance and repair operations. To make LSP applicable at Maintenance Repair Overhaul (MRO) and ensure reasonably simple setup and easy transportability requires developing a “portable” device. A newly developed low energy portable equipment (LEOPARD™) for MRO deployment capable of LSP in fully assembled aircraft will be presented. LEOPARD™, is the first around the world laser peening portable equipment receiving ATEX (Atmosphere Explosive Environment) certification for CLASS IV laser.
Keynote4: Dongil Kwon (Seoul National University)
Title: Material Restoration by Ultrasonic Nanocrystal Surface Modification (UNSM) and Measurement of Mechanical Property and Residual Stress Using Instrumented Indentation Technique (IIT)
In this study, an ultrasonic nanocrystal surface modification (UNSM) technology is considered a surface severe plastic deformation (S2PD) method, which increases the hardness of the material and also transfers tensile residual stress into compressive residual stress. The effect of UNSM technology on the hardness and residual stress of in-service components can be measured directly in the field by an instrumented indentation technique (IIT) to understand the hardening and generation of compressive residual stress mechanisms. The IIT can evaluate not only hardness but also fracture characteristics and residual stress based on analytic interpretation of the indentation load-depth curve of the target material. Also, IIT can be directly applied to the structure under operation or installation where destructive test cannot be performed due to the issues of collect specimens. And IIT can be a very good alternative. Therefore, for the safe use of large facilities, IIT and UNSM technology can be used to accurately predict the lifespan through the regular on-site diagnosis of facility component.
Keynote5: Tomáš Mocek (HiLASE Centre)
Title: Pioneering high average power laser technology at HiLASE
Recent advances in high average power pulsed laser sources and technologies at the HiLASE Centre of Excellence will be presented. We have demonstrated efficient and stable operation of diode pumped solid state laser system BIVOJ delivering 145 J, 10 ns, 1030 nm pulses at 10 Hz thus confirming the power scalability of multi-slab cryogenic gas-cooled Yb:YAG amplifier technology. We have also achieved kilowatt-class high energy frequency conversion at 515 nm, and half-kilowatt-class at 343 nm, respectively. Recently, a Faraday isolator capable of stable protection of the laser amplifier chain delivering 100 J nanosecond laser pulses at the repetition rate of 10 Hz has been developed and successfully tested. The thin-disk laser platform PERLA® has been developed, capable of generating 1-ps pulses with an average power of up to 500 W at a wavelength of 1030 nm, with exceptional beam quality and power stability. Both laser platforms are employed in diverse high-tech industrial and scientific applications such as laser shock peening, laser nano-processing, material functionalization, laser damage studies, particle generation & acceleration, and laser propulsion.
Keynote6: Laurent Berthe (Lab PIMM CNRS)
Title: Towards reliable and versatile laser shock application: from Laser to parts.
The expansion of application of shock produced by laser plasma is often limited by the lack of process control. Since last conference, many progresses have been done on all topics : Laser metrology, Beam focalisation, laser interaction. These efforts make possible new applications requiring reliable and versatile loadings : adhesion test, laser damaging, mechanical testing at high strain rate. Some propose also perspective for Laser shot peening. This keynote will present an exhaustive review on these new developments accessible for the communauty of laser shock and material science. It will show some demonstrations on industrial applications very promising. It will open discussions on new issues and perspectives for academic and industry.
Keynote7: Yongxiang Hu (Shanghai Jiao Tong University)
Title: Laser peening of large-scale components: modeling, optimization and applications.
large-scale components such as integral panels, are commonly used in the aerospace industries. How to design the process is challenge for the application of laser peening in these components for shape control and fatigue resistance. In this talk, we present the recent progress in the modeling of laser peening process, which include dynamic and static model by including crystal plasticity in mesoscale, and further propose an inverse problem framework for the process design of laser peen forming. Finally, we provide several cases for laser peening of large-scale components to demonstrate the model capabilities.
Keynote8: Michael Fitzpatrick (Coventry University)
Title: Laser shock peening: recent developments and a look ahead
Laser shock peening (LSP) has become an accepted and valued method of surface engineering, with numerous successful applications in high-value industries including aerospace and nuclear power. Its growth in application has slowed in recent years, so the question needs to be asked as to where it fits into the landscape of manufacturing and repair technologies. To-date, almost all the applications of LSP have been in surface treatment for the improvement in fatigue lifetime, through the introduction of deep, high-magnitude, compressive residual stress that acts to prevent or delay the initiation of cracks, and reduce their growth rate when and if initiated. The method has shown itself to be highly successful for this, with the proviso that the peak stress in the component needs to co-locate with the compressive layer induced by the LSP. For many aerospace structures, life enhancement involves the retardation of a long, growing, crack that may be many millimetres in length; and that in consequence is already generating high levels of stress intensity factor at the crack tip. As peening of the entire structure is neither feasible nor desirable, the possibility of using localised peen patches as crack retarding features is being actively explored. This talk will present results of recent work on the effectiveness of peen patches in aerospace aluminium for crack retardation, as well as methods for optimum peening of assemblies during manufacturing. It will also look at the challenges for widespread adoption of LSP into new, high-volume, manufacturing industries.
Keynote9: Vijay K Vasudevan (University of North Texas)
Title: Progress in the Engineering Science and Application of Laser Shock Peening and Related Mechanical Surface Treatments in Materials Manufacturing and Future Opportunities
Research, modeling, and application of advanced mechanical surface treatments like laser shock peening (LSP) has grown considerably in the past four decades, from initially and mainly aerospace/engine to the biomedical and energy sectors (USC powerplants, nuclear). In this talk, the advances made in the understanding of the effects of various types of advanced mechanical surface treatments on residual stress generation and near-surface microstructural modifications in a variety of materials for various applications will be reviewed and discussed, including newer approaches such as coating-free and hybrid treatments. Future opportunities for application and integration of these techniques in additive manufacturing of parts and use of modeling and machine learning approaches for predictive purposes and process design will also be discussed.
Keynote10: Yuji Kobayashi (Sintokogio, LTD.)
Title: Outlook for the contract business using Laser peening in Japan
Sintokogio is proud to be a leading company in surface treatment processing in Japan, and shot peening is one of our core technology. We have established a wealth of knowledge through the application of shot peening to automotive parts and other products. On the other hand, there are only a few manufacturers in the world that use laser peening. Characteristics of shot peening and laser peening are clearly different. Therefore, it is necessary to determine the processing conditions according to the characteristics of both technologies and the target material or purpose of use. Naturally, measurement and verification of the effects are required. Therefore, we installed "The Procudo® Laser Peening System" from LSPT, which is the top manufacturer of laser peening, for the first time in Japan, and established a laser peening contract processing company that combines our original knowledge of peening with LSPT's know-how. This specialized company was established in June 2023. In this presentation, we will explain the appplication of laser peening and shot peening in Japan and its expectations.