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Masatoshi Futakawa - One of the best experts on this subject based on the ideXlab platform.

  • Study on the evaluation of Erosion Damage by using laser ultrasonic integrated with a wavelet analysis technique
    Journal of Physics: Conference Series, 2017
    Co-Authors: Tao Wan, Masatoshi Futakawa, Takashi Naoe, Takashi Wakui, Hironari Obayashi, Toshinobu Sasa
    Abstract:

    Spallation targets are the key components of accelerator driven systems (ADSs) that are being developed in the world. Erosion Damages on the target vessels are anticipated. To prevent accidents occurrence due to Erosion of spallation target vessel, the Damage evaluation technique is desirable. The excited vibration of LBE target vessel will be monitored remotely to establish the technique. In this study, the basic researches were carried out through experiments and numerical simulations to investigate the interaction between ultrasonic waves and Damage to understand the correlation between structural vibration and Damage degree. Specimens with distributed Erosion Damage was irradiated by laser shots, and the vibration was detected by a laser vibrometer subsequently. A technique, Wavelet Differential Analysis (WDA), was developed to quantitatively and clearly indicate the differences caused by Damage in the vibration signals. The results illustrated that the developed technique is sensitive to Erosion Damage with small size and is capable of quantitatively evaluating Erosion Damage. It is expected that the developed techniques can be applied to monitor the real spallation targets in the future.

  • Erosion Damage of laser alloyed stainless steel in mercury
    Surface and Coatings Technology, 2007
    Co-Authors: Sergey Zherebtsov, Masatoshi Futakawa, Takashi Naoe, Katsuhiro Maekawa
    Abstract:

    Abstract The effect of laser surface alloying of type 316 stainless steel on the Erosion resistance in mercury has been investigated. The alloying was produced by melting predeposited Al–Si powder and a portion of underlying substrate with a pulsed Nd:YAG laser beam. The microhardness of the modified layer was found to be 2.5 times higher than that of untreated steel. The Erosion test of laser alloyed surface and steel in mercury was carried out by using the electromagnetic impact testing machine. The laser alloyed surface was found to be less Damaged after 105 cycles of impacts compared to untreated stainless steel. However, after 106 cycles the Erosion resistance of the modified layer is much lower than that of untreated steel. Liquid metal embrittlement in contact with mercury and residual stresses were considered as factors impairing the Erosion resistance of the laser alloyed surface.

  • Damage diagnostic of localized impact Erosion by measuring acoustic vibration
    Journal of Nuclear Science and Technology, 2004
    Co-Authors: Masatoshi Futakawa, Hiroyuki Kogawa, Tomoki Naoe, Yujiro Ikeda
    Abstract:

    High power spallation targets for neutron sources are being developed in the world. Mercury target will be installed at the material and life science facility in J-PARC, which will promote innovative science. The mercury target is subject to the pressure wave caused by the proton bombarding mercury. The pressure wave propagation induces the cavitation in mercury that imposes localized impact Erosion Damage on the target vessel. The impact Erosion is a critical issue to decide the lifetime of the target. The electric Magnetic IMpact Testing Machine, MIMTM, was developed to produce the localized impact Erosion Damage and evaluate the Damage formation. Acoustic vibration measurement was carried out to investigate the correlation between the Erosion Damage and the Damage potential derived from acoustic vibration. It was confirmed that the Damage potential related with acoustic vibration is useful to predict the Damage due to the localized impact Erosion and to diagnose the structural integrity.

  • Erosion Damage on solid boundaries in contact with liquid metals by impulsive pressure injection
    International Journal of Impact Engineering, 2003
    Co-Authors: Masatoshi Futakawa, Hiroyuki Kogawa, Ryutaro Hino, Hidefumi Date, Hiroyuku Takeishi
    Abstract:

    Abstract The Japan Atomic Energy Research Institute is carrying out research and development to construct a spallation neutron source facility, which may bring innovative science fields. A high-power proton beam will be injected into a liquid-mercury target to produce neutrons. The mercury vessel will consequently be subjected to the pressure waves generated by rapid thermal expansion. The pressure waves will propagate from the liquid mercury into the vessel solid metal, and back again. The pressure waves may induce Erosion at the interface between the solid metal vessel and the liquid mercury under certain loading conditions, e.g. impact. In order to investigate the impact Erosion Damage due to the pressure wave, we have carried out impact experiments using a modified conventional split Hopkinson pressure bar apparatus on mercury filling a small chamber. The chamber for the mercury consists of the input, the output bars and a collar. Disk specimens of 16 mm diameter and 5 mm thickness (A6061, 316SS, Inconel 600 and Maraging steel) were placed on the ends of both bars in contact with mercury. Surface degradation in the form of many pits was observed for pressure waves of 40 and 80 MPa, which are significantly lower than the yield stress of these metals. The ranking order of Damage was found to be A6061>316SS≅Inconel 600>Maraging steel. In particular, A6061 fractured completely after 100 impacts.

Volker Prasuhn - One of the best experts on this subject based on the ideXlab platform.

  • applying Erosion Damage mapping to assess and quantify off site effects of soil Erosion in switzerland
    Land Degradation & Development, 2010
    Co-Authors: Thomas Ledermann, Karl Günter Herweg, Hanspeter Liniger, Flurina Schneider, Hans Hurni, Volker Prasuhn
    Abstract:

    In order to fill existing knowledge gaps in the temporal and spatial distribution of soil Erosion, its sources and causes, as well as in relation to its off-site impacts, Erosion Damage mapping of all visible Erosion features was carried out at three study sites in Switzerland. The data illustrate that about one-quarter of the cultivated land was affected by water Erosion. Observed mean annual soil loss rates are considered rather low (0.7–2.3 t/ha/y) compared to other European countries. However, substantial losses of >70 t/ha were recorded on individual plots. This paper focuses on the spatial aspects of soil Erosion, by observing and comparing the study areas in a 1-year period from October 2005 to October 2006. The analyses illustrate that the sites differ considerably in average soil loss rates, but show similar patterns of off-site effects. In about one-third of the Damaged plots an external source of surface runoff upslope contributed to the Damage (run-on). Similarly, more than 50 per cent of the soil eroded on arable land deposited downslope on adjacent plots, roads, public/private infrastructure, etc., and 20 per cent of it reached open water bodies. Large amounts of eroded soil which deposit off-site, often related to slope depressions, are considered muddy floods and were frequently observed in Switzerland. Mapping, in conclusion, helps to sheds light on some of the important challenges of today, in particular: to comprehensively assess socioeconomic and ecological off-site effects of soil Erosion, to attribute off-site impacts to on-site causes, and to raise awareness of all stakeholders involved, in order to improve ongoing discussions on policy formulation and implementation at the national and international levels.

  • Applying Erosion Damage mapping to assess and quantify off‐site effects of soil Erosion in Switzerland
    Land Degradation & Development, 2010
    Co-Authors: Thomas Ledermann, Karl Günter Herweg, Hanspeter Liniger, Flurina Schneider, Hans Hurni, Volker Prasuhn
    Abstract:

    In order to fill existing knowledge gaps in the temporal and spatial distribution of soil Erosion, its sources and causes, as well as in relation to its off-site impacts, Erosion Damage mapping of all visible Erosion features was carried out at three study sites in Switzerland. The data illustrate that about one-quarter of the cultivated land was affected by water Erosion. Observed mean annual soil loss rates are considered rather low (0.7–2.3 t/ha/y) compared to other European countries. However, substantial losses of >70 t/ha were recorded on individual plots. This paper focuses on the spatial aspects of soil Erosion, by observing and comparing the study areas in a 1-year period from October 2005 to October 2006. The analyses illustrate that the sites differ considerably in average soil loss rates, but show similar patterns of off-site effects. In about one-third of the Damaged plots an external source of surface runoff upslope contributed to the Damage (run-on). Similarly, more than 50 per cent of the soil eroded on arable land deposited downslope on adjacent plots, roads, public/private infrastructure, etc., and 20 per cent of it reached open water bodies. Large amounts of eroded soil which deposit off-site, often related to slope depressions, are considered muddy floods and were frequently observed in Switzerland. Mapping, in conclusion, helps to sheds light on some of the important challenges of today, in particular: to comprehensively assess socioeconomic and ecological off-site effects of soil Erosion, to attribute off-site impacts to on-site causes, and to raise awareness of all stakeholders involved, in order to improve ongoing discussions on policy formulation and implementation at the national and international levels.

  • Erosion Damage Mapping: Assessing Current Soil Erosion Damage in Switzerland
    2008
    Co-Authors: Thomas Ledermann, Karl Günter Herweg, Hanspeter Liniger, Flurina Schneider, Hans Hurni, Volker Prasuhn
    Abstract:

    Within the scope of a comprehensive assessment of the degree of soil Erosion in Switzerland, common methods have been used in the past including test plot measurements, artificial rainfall simulation, and Erosion modelling. In addition, mapping guidelines for all visible Erosion features have been developed since the 1970s and are being successfully applied in many research and soil conservation projects. Erosion Damage has been continuously mapped over a period of 9 years in a test region in the central Bernese plateau. In 2005, two additional study areas were added. The present paper assesses the data gathered and provides a comparison of the three study areas within a period of one year (from October 2005 to October 2006), focusing on the on-site impacts of soil Erosion. During this period, about 11 erosive rainfall events occurred. Average soil loss rates mapped at each study site amounted to 0.7 t ha-1, 1.2 t ha-1 and 2.3 t ha-1, respectively. About one fourth of the total arable land showed visible Erosion Damage. Maximum soil losses of about 70 t ha-1 occurred on individual farm plots. Average soil Erosion patterns are widely used to underline the severity of an Erosion problem (e.g. impacts on water bodies). But since severe rainfall events, wheel tracks, headlands, and other “singularities” often cause high Erosion rates, analysis of extreme Erosion patterns such as maximum values led to a more differentiated understanding and appropriate conclusions for planning and design of soil protection measures. The study contains an assessment of soil Erosion in Switzerland, emphasizing questions about extent, frequency and severity. At the same time, the effects of different types of land management are investigated in the field, aiming at the development of meaningful impact indicators of (un-)sustainable agriculture/soil Erosion risk as well as the validation of Erosion models. The results illustrate that conservation agriculture including no-till, strip tillage and in-mulch seeding plays an essential role in reducing soil loss as compared to conventional tillage.

Douglas R Bruce - One of the best experts on this subject based on the ideXlab platform.

  • cavitation induced Erosion in liquid metal spallation targets a comparison between a predictive method and measured Erosion Damage to stainless steel target modules at the spallation neutron source
    Wear, 2020
    Co-Authors: Drew E Winder, David A Mcclintock, Douglas R Bruce
    Abstract:

    Abstract Neutrons are produced for neutron scattering instruments at the Spallation Neutron Source by bombarding liquid mercury with a pulsed high-energy proton beam. The liquid mercury target material flows through a replaceable stainless-steel target vessel and cavitates during operation due to the extremely high heating rate caused by each proton pulse. Cavitation-induced Erosion Damage to the mercury-facing surfaces of target vessels is a key concern for target lifetime and has been the subject of considerable research. While numerous experiments have studied and modeled the progression of cavitation Erosion Damage to liquid metal target containers, direct quantitative measurements of actual Erosion of a spallation target vessel were previously not available. Recently, the Erosion Damage to multiple target vessels operated at the Spallation Neutron Source was measured using a high-resolution laser scanning system, which provided an opportunity to study the efficacy of a cavitation Damage progression model. In this paper, a cavitation progression modeling procedure developed using empirical observations is compared to measurements of samples from target vessels after operation. The strengths and limitations of the technique are discussed and methods for improving future modeling and predictive accuracy are proposed.

  • Cavitation-induced Erosion in liquid metal spallation targets – A comparison between a predictive method and measured Erosion Damage to stainless steel target modules at the Spallation Neutron Source
    Wear, 2020
    Co-Authors: Drew E Winder, David A Mcclintock, Douglas R Bruce
    Abstract:

    Abstract Neutrons are produced for neutron scattering instruments at the Spallation Neutron Source by bombarding liquid mercury with a pulsed high-energy proton beam. The liquid mercury target material flows through a replaceable stainless-steel target vessel and cavitates during operation due to the extremely high heating rate caused by each proton pulse. Cavitation-induced Erosion Damage to the mercury-facing surfaces of target vessels is a key concern for target lifetime and has been the subject of considerable research. While numerous experiments have studied and modeled the progression of cavitation Erosion Damage to liquid metal target containers, direct quantitative measurements of actual Erosion of a spallation target vessel were previously not available. Recently, the Erosion Damage to multiple target vessels operated at the Spallation Neutron Source was measured using a high-resolution laser scanning system, which provided an opportunity to study the efficacy of a cavitation Damage progression model. In this paper, a cavitation progression modeling procedure developed using empirical observations is compared to measurements of samples from target vessels after operation. The strengths and limitations of the technique are discussed and methods for improving future modeling and predictive accuracy are proposed.

Fan Jincheng - One of the best experts on this subject based on the ideXlab platform.

  • Experimental study into Erosion Damage mechanism of concrete materials in a wind-blown sand environment
    Construction and Building Materials, 2016
    Co-Authors: Hao Yunhong, Yujiang Feng, Fan Jincheng
    Abstract:

    Abstract Based on the knowledge that concrete structures in the mid-west of Inner Mongolia are subject to Erosion caused by the wind and sand environment over a long period of time, sediment-air injection method was used for an experimental study into Erosion on concrete in the wind-blown sand environment, and then involving analysis of concrete Erosion features and Erosion behavior law. The results show that: The Erosion rate increases with the increasing impact velocity, the two have an empirical power law relationship, and under same Erosion condition, it is found that the velocity exponent (n) in the Erosion rate equation (E = kVn) increases with the increasing concrete strength; as the impact angle increases, the concrete Erosion rate also increases; the Erosion resistance of concrete is first decreasing then increasing with the erodent feed rate, the Erosion rate is most obvious as the abrasive feed rate at a certain range (in this paper, the abrasive feed rate is around 90 g/min); under the same conditions, for concretes with different strengths, the Erosion rate decreases with an increase in strength; Erosion of concrete has no apparent incubation period but has a rising and stable period, and the accumulative mass loss due to Erosion almost increases linearly. The surface micrograph of concrete specimen after Erosion were observed by scanning electron microscope (SEM), then the concrete Erosion Damage mechanism was discussed and it was proposed that there were two mechanisms: surface scratch failure mechanism at low impact angles and impact indentation crushing mechanism at high impact angles during the concrete Erosion, which can provide an explanation for failure of concrete materials. The relationship between the experimental results and the actual wind-blown sand Erosion conditions was obtained by similarity analysis.

Mamoun Medraj - One of the best experts on this subject based on the ideXlab platform.

  • Water droplet Erosion mechanism of nearly fully-lamellar gamma TiAl alloy
    Materials & Design, 2016
    Co-Authors: M.s. Mahdipoor, Dmytro Kevorkov, P. Jedrzejowski, Mamoun Medraj
    Abstract:

    Abstract Water droplet Erosion (WDE), is a known mechanical degradation and progressive Damage for turbine blades in the power generation and aerospace industries. Hence, water droplet Erosion study of TiAl as an important structural material in such industries would be very attractive. The current work is to investigate the Erosion Damage mechanism of nearly fully lamellar Ti45Al2Nb2Mn0.8TiB 2 (45-2-2XD) alloy. This alloy was subjected to water droplet Erosion using 460 μm droplets and 350 ms − 1 impact speed. In order to track the Erosion Damage, WDE test was interrupted at different stages; incubation, maximum Erosion rate and final steady state stages. The eroded specimens were characterized using optical microscope (OM), scanning electron microscope (SEM) and atomic force microscope (AFM). The qualitative and quantitative study reveals that the Erosion Damage of TiAl initiates by inhomogeneous and localized material flow followed by crack network generation on the surface. Such cracks mainly nucleate on the interlamellar slip bands and cause delamination of lamellae. Further droplet impacts result in the cracks coalescence and subsequent micro-pitting within the colonies. In the advanced stages, the Erosion Damage was governed by periodic water roughening and water polishing, which were observed on the bottom and the sidewalls of deep Erosion craters.