Faculty Profiles - MURATA Yorinobu

Published Papers - MURATA Yorinobu

Division display >> ／ All the affair displays1 - 64 of about 64

Improvement of Self-shape Measurement Accuracy in a Self-sensing Flexible Array Probe

Kohta Yoshikawa, Yorinobu Murata （Part： Corresponding author )

IEEJ Transactions on Electronics, Information and Systems ( 日本電気学会 ) 143 ( 9 ) 854 - 861 2023.09 [Refereed]

Study on the FDTD Method Considering the Asymmetric Apparent Elastic Constant for Surface SH-wave Acoustoelasticity

Tomofumi SHINGU, Yorinobu MURATA （Part： Last author )

Journal of JSNDI ( The Japanese Society for Non-Destructive Inspection ) 72 ( 6 ) 236 - 241 2023.06 [Refereed]

Study on Visualization of Bubbles in a Tube using M-Sequence Encoding Array Transducer

Shoichiro Yamamoto, Kazuki Yamamoto and Yorinobu Murata （Part： Corresponding author )

IEEJ Transactions on Electronics, Information and Systems 142 ( 12 ) 948 - 955 2022.12 [Refereed]

Adjacent Defects Detection using a Sparse Modeling of Ultrasonic Testing System

Shinichiro Fukumoto, Yorinobu Murata （Part： Last author )

IEEJ Transactions on Electronics, Information and Systems 141 ( 9 ) 948 - 955 2021.09 [Refereed]

空中超音波を用いた衣服着用状態における前腕の非接触二次元形状計測

屋木悠佑,村田頼信（Part： Corresponding author )

電気学会論文誌C 139 ( 11 ) 1310 - 1315 2019.11 [Refereed]

Study on Pulse Compression Ultrasonic Imaging by a Stacked M-Sequence Encoding Probe

YORINOBU MURATA and DAIYU KANEDA （Part： Lead author )

Electrical Engineering in Japan 207 ( 1 ) 36 - 42 2019.04 [Refereed]

Reduction of temperature influence in stress measurement using surface SH‐wave acoustoelasticity

Katsuhiko Kitano, Yorinobu Murata （Part： Corresponding author )

Electrical Engineering in Japan 206 ( 3 ) 17 - 23 2019.01 [Refereed]

ラム波の非線形性を利用したシリコンウェーハのマイクロクラック検査に関する基礎的検討

村田頼信,西川美沙都,松田正誉（Part： Lead author )

電気学会論文誌C 138 ( 12 ) 1566 - 1572 2018.12 [Refereed]

A Method of Generating Reference Wave in Interferometric Measurement with Multiple Imaging Sensors

Fujigaki, M, Otsuka, N, Murata, Y （Part： Last author )

Optics and Lasers in Engineering 110 377 - 383 2018.11 [Refereed]

DOI

Interferometric Trigger Method with Dual Piezoelectric Transducers for Digital Holographic Interferometry

Fujigaki, M, Minamino, H, Murata, Y （Part： Last author )

Optical Engineering 57 ( 11 ) 1114105- - 114105-5 2018.11 [Refereed]

DOI

表面SH波音弾性法を用いた応力測定における温度影響の低減

北野勝彦,村田頼信（Part： Corresponding author )

電気学会論文誌C 138 ( 9 ) 1082 - 1087 2018.09 [Refereed]

Prototype of Multi-Line Bundle Fibers with LED Light Sources for 3D Shape Measurement Using Talbot Fringe Projection

Sakano, T, Hayashi, T, Fujigaki, M, Murata, Y （Part： Last author )

Journal of the Japanese Society for Experimental Mechanics 18 ( 1 ) 43 - 49 2018.03 [Refereed]

Study on Pulse Compression Ultrasonic Imaging by a Stacked M-sequence Encoding Probe

Murata Yorinobu, Kaneda Daiyu （Part： Lead author )

IEEJ Transactions on Electronics, Information and Systems ( The Institute of Electrical Engineers of Japan ) 137 ( 9 ) 1153 - 1158 2017.09 [Refereed]

<p>If an ultrasonic imaging inside an object is possible without scanning by using an ultrasonic probe having a small aperture, the ultrasonic imaging system becomes a simpler and easier system. We have developed a stacked encoding ultrasonic transducer which can transceive an M-sequence signal only by a pulse drive in order to realize an ultrasonic measurement with a high resolution and high sensitivity. When an ultrasonic probe with such transducer is used, a pulse compression measurement is enabled only with a general ultrasonic flaw detector and a PC without using special devices. In this study, we focused on the characteristic that the received waveform by this probe changes with transceiver directions of a wave. A stacked M-sequence encoding probe of 7 bits length was manufactured and the one-dimensional point spread function in transceiver angle was obtained. As a result, it was confirmed that this probe has not only the pulse compression characteristic but the angle selecting characteristic. Finally, by using the proposed probe, the cross-sectional imaging for point objects without scanning was demonstrated.</p>

DOI

Influences of Liquid Temperature on Flow Rate Measurements using Guided Waves Generated from Ring Transducers

Matsuda Masataka, Nishikawa Misato, Murata Yorinobu （Part： Corresponding author )

IEEJ Transactions on Electronics, Information and Systems ( The Institute of Electrical Engineers of Japan ) 137 ( 9 ) 1159 - 1164 2017.09 [Refereed]

<p>Micro flow rate measurements are required for manufacturing and medical fields. Straight type ultrasonic flowmeter can measure the liquid flow by using guided waves. However, guided waves propagate by vibrating intricately along boundaries, so it is difficult to reveal their characteristics. In addition, the time difference between two receiving waves across two transducers differs depending on the temperature of the liquid, which can cause errors in flow rate measurements. In this paper, the theoretical analysis method for guided wave flowmeter is introduced to investigate the influence of water temperature on flow rate measurement. The simulated time difference is calculated by using this method, while the experimental time difference is obtained in a circulation system. By comparing simulated and experimental values, this theoretical analysis can be confirmed to be valid for revealing the temperature dependence.</p>

DOI

ガイド波を用いた流量測定における周波数が測定に与える影響

松田正誉, 西川美沙都, 村田頼信（Part： Corresponding author )

ESI-NEWS 35 ( 1 ) 6 - 11 2017.02 [Refereed]

Application of phase-shifted fringe projection method with linear fiber arrays using talbot effect to height measurement of BGA

Motoharu Fujigaki, Takumi Hayashi, Yorinobu Murata （Part： Last author )

Springer Proceedings in Physics ( Springer Science and Business Media, LLC ) 194 41 - 47 2017 [Refereed]

DOI

Development of a compact 3D shape measurement unit using the light-source-stepping method

Motoharu Fujigaki, Toshimasa Sakaguchi, Yorinobu Murata （Part： Last author )

OPTICS AND LASERS IN ENGINEERING ( ELSEVIER SCI LTD ) 85 9 - 17 2016.10 [Refereed]

A compact 3D shape measurement unit that uses the light-source-stepping method (LSSM) is developed. The LSSM proposed by the authors is a phase-shifting fringe projection method for shape measurement. The authors also developed a linear LED device for high-speed shape measurement using the LSSM. A compact and high-speed 3D shape measurement unit can be realized using a linear LED device. However, the LSSM is difficult to utilize because the phase-shifting amount is not uniform. The phase-shifting amount depends on the distance from the grating plate. It is therefore necessary to consider carefully the locations of the linear LED device and the grating plate. In this paper, the design method for a 3D shape measurement unit that uses the LSSM is shown, and a prototype of a compact 3D shape measurement unit with a linear LED device is developed. (C) 2016 The Authors. Published by Elsevier Ltd.

DOI

スペックル干渉法を用いた超音波ホログラフィ画像撮像システムの構築

山口論人,村田頼信,藤垣元治（Part： Corresponding author )

電気学会論文誌C 136 ( 8 ) 1056 - 1062 2016.08 [Refereed]

Talbot効果による傾斜角度格子投影手法とリニアファイバアレイを用いた位相シフトによる3次元計測

林拓実, 村田頼信, 藤垣元治（Part： Last author )

電気学会論文誌C 136 ( 8 ) 1063 - 1070 2016.08 [Refereed]

Application of Surface SH-wave Acoustoelasticity for Axial Stress Measurement of Railroad Long Rail

Murata, Y, Miyazaki, H, Matsumaru, K, Sendai, M, Fujigaki, M （Part： Lead author,　Corresponding author )

J. JSEM ( The Japanese Society for Experimental Mechanics ) 16 ( 1 ) 47 - 52 2016.04 [Refereed]

On railroad tracks, in order to improve a riding comfortability and a noise suppression, the introduction of long rail is advanced in recent years. However, because a long rail is concluded on the long section, the elasticity of the rail accompanying a temperature change is restrained and consequently an axial stress generates. In case of the big axial stress, there is a possibility of causing a buckling and a tension fracture in railroad rail. In this study, we carried out the basic examination for applying a surface SH-wave acoustoelastic method to the stress measurement as an axial stress management of railroad long rails. This method is able to measure the stress of metallic materials nondestructively, even if the initial value, an acoustic anisotropy by the texture, is unknown. A T-type surface SH-wave sensor was improved for the railroad rail and the residual stress measurement in a 50 kgN rail being used for long rails of conventional lines was tried. As the result, it was demonstrated that this sensor was able to measure the residual stress nondestructively by comparing with a strain gage testing. Moreover, in order to measure the axial stress of a long rail, the side of head of the rail has been found out as a suitable measurement point which is unaffected by residual stress. On the other hand, considering the effect of thickness of the rail, it was found that the axial stress in a railroad long rail would be able to measure accurately by compensating acoustoelasticity coefficient.

DOI

Dynamic Deflection Angle Distribution Measurement Using Sampling Moiré Method

Fujigaki, M, Tomita, D, Murata, Y

J. JSEM ( 日本実験力学会 ) 15 ( 4 ) 315 - 319 2015.12 [Refereed]

Proposal for Precision Prediction Method for Depth Measuring Microscope Using Grating Projection Method

Kaneko, K, Fujigaki, M, Murata, Y

Journal of JSEM ( The Japanese Society for Experimental Mechanics ) 15 ( 3 ) 210 - 216 2015.09 [Refereed]

The purpose of this study is to propose predictive method of the measuring precision of the depth measuring microscope using a technique that combines a whole-space tabulation method (WSTM) and light-source stepping method. The WSTM excludes almost all of systematic errors such as the influence of a lens distortion and deformation of the brightness distribution of the projected grating from the measured result. Therefore, it becomes possible to predict the precision of a measurement device by only considering the random error caused by camera noise and caused by reflectance characteristics of the surface of an object. In this study, a precision prediction method for depth measuring microscope using grating projection method is proposed. The effectiveness of the predictive method is verified by comparing the predicted precision and the measuring precision. The theory and experimental results are shown.

DOI

Development of M-sequence Pulse Compression Ultrasonic Transducer by Stacking Piezoelectric Polymer Films

Murata, Y, Kaneda, D, Yonenaka, H, Fujigaki, M

Journal of JSEM 15 ( Special Issue ) s65 - s69 2015.08 [Refereed]

Projection Method of Small Pitch Fringe Pattern Using Talbot Effect with Super Luminescent Diode for 3D Shape Measurement

Hayashi, T, Fujigaki, M, Murata, Y

Journal of JSEM 15 ( Special Issue ) s81 - s86 2015.08 [Refereed]

Prototype of a Handheld Displacement Measurement System Using Multiple Imaging Sensors

M. Fujigaki, H. Minamino, N. Ikoma, H. Tamai and Y. Murata （Part： Last author )

Journal of JSEM 15 S70 - 74 2015.07 [Refereed]

Deformation Distribution Measurement from Oblique Direction Using Sampling Moire Method

Daiki Tomita, Motoharu Fujigaki, Yorinobu Murata

ADVANCEMENT OF OPTICAL METHODS IN EXPERIMENTAL MECHANICS, VOL 3 ( SPRINGER-VERLAG BERLIN ) 3 197 - 204 2015 [Refereed]

A sampling Moire method is one of a deformation measurement method of a large structure such as a building and a bridge. The accuracy of phase difference analysis is from 1/100 to 1/1,000 of the grating pitches. This method can analyze two-dimensional phases from a two-dimensional grating image attached on the surface of a specimen. The phase difference distribution before and after deformation gives displacement distributions for the x- and the y-directions. Grating phase also gives position for the x- and the y-directions. Therefore, the relationship between a point on an image and the corresponding point on the object can be obtained without any calibrations. A sampling Moire camera we proposed has an FPGA with an algorithm of the sampling Moire method inside the camera. It can output two-dimensional phases and phase differences from a single shot two-dimensional grating image in real-time. In this paper, a measurement accuracy of the deformation distribution measurement using the sampling Moire camera placed in the oblique direction is estimated. Experimental result of the time-series deformation measurement of a moving cantilever is shown.

DOI

High-speed shape measurement with 4 kHz using linear LED device

Motoharu Fujigaki, Yohei Oura, Daisuke Asai, Yorinobu Murata

Conference Proceedings of the Society for Experimental Mechanics Series 3 13 - 19 2014 [Refereed]

High-speed shape measurement is required to analysis the behavior of a breaking object, a vibrating object or a rotating object. A shape measurement by a phase shifting method can measure the shape with high spatial resolution because the coordinates can be obtained pixel by pixel. A light source stepping method (LSSM) using linear LED array was proposed by authors. Accurate shape measurement can be performed by a whole space tabulation method (WSTM). The response speed of the LED array is more than 12 kHz. In this paper, high-speed shape measurement is performed with a high-speed camera by WSTM and LSSM using a linear LED array. The phase shifting is performed in 12,000 Hz and the shape measurement of a rotating fan is performed in 4,000 Hz. © The Society for Experimental Mechanics, Inc. 2014.

DOI

High-speed height measurement by a light-source-stepping method using a linear LED array

Motoharu Fujigaki, Yohei Oura, Daisuke Asai, Yorinobu Murata

OPTICS EXPRESS ( OPTICAL SOC AMER ) 21 ( 20 ) 23169 - 23180 2013.10 [Refereed]

High-speed height measurement is required in industrial fields for analyzing the behavior of a breaking object, a vibrating object or a rotating object. A shape measurement performed using a phase-shifting method can measure the shape with high spatial resolution because the coordinates can be obtained pixel by pixel. A light-source-stepping method (LSSM) that uses a linear LED array by means of a whole-space tabulation method (WSTM) has been proposed. Accurate shape measurement can be performed using this method. The response speed of the LED array is greater than 12 kHz. In this paper, height measurement is performed using WSTM and LSSM with a linear LED array and a high-speed camera. It was verified that the response speed of the linear LED is greater than 200 kHz. The phase shifting was performed at 12 kHz, and the height measurement of the vibrating woofer was performed at 4 kHz using a 3-step phase-shifting method. (C) 2013 Optical Society of America

DOI

Prototype of Compact Strain Measurement Equipment with Multiple Imaging Device Using Phase-shifting Digital Holography

Fujigaki Motoharu, Minamino Hiroki, Murata Yorinobu

Proceedings of JSPE Semestrial Meeting ( The Japan Society for Precision Engineering ) 2013 421 - 422 2013

DOI

Development and evaluation of compact 3D shape measurement system using linear LED device.

Sakaguchi Toshimasa, Fujigaki Motoharu, Murata Yorinobu

Proceedings of JSPE Semestrial Meeting ( The Japan Society for Precision Engineering ) 2013 425 - 426 2013

Recently, accurate and compact shape measurement system that can be installed into a production line is required in the industrial field. In my laboratory, we proposed linear LED device. A grating projector is composed with the device. The phase of the projected grating on measured object can be shifted with changing the position of lighted linear LED easily and quickly. In this paper, we developed a shape measurement system using the linear LED device and evaluated accuracy of this system.

DOI

Accuracy Improvement Method using Two Projectors Placed in Symmetrical Position on Shape Measurement with Grating Projection Method

Shima Atsushi, Fujigaki Motoharu, Murata Yorinobu

Proceedings of JSPE Semestrial Meeting ( The Japan Society for Precision Engineering ) 2013 429 - 430 2013

近年，三次元物体の形状を非接触で計測する技術は，多くの分野で必要とされている．この一つに，物体に投影した格子模様のゆがみを解析し形状を導く格子投影法がある．しかし，計測対象物の模様や汚れなど，物体表面の反射率に差異が存在する場合には，反射率の境界部分に計測誤差が生じる問題があった．そこで，本研究ではプロジェクター2台を用いて，この誤差を低減し精度向上を行なう手法を提案する．

DOI

Characteristic evaluation of linear LED grating projector for highspeed shape measurement

Motoharu Fujigaki, Tsutomu Yokoyama, Yohei Oura, Toshimasa Sakaguchi, Daisuke Asai, Yorinobu Murata

Proceedings of SPIE - The International Society for Optical Engineering 8769 2013 [Refereed]

High-speed shape measurement is required to analysis the behavior of a breaking object, a vibrating object or a rotating object. A shape measurement by a phase shifting method can measure the shape with high spatial resolution because the coordinates can be obtained pixel by pixel. The key-device is a grating projector. The projector can shift the projected grating in high-speed. So, authors proposed a light source stepping method using a linear LED device. A grating projector is composed with the linear LED and a Ronchi ruling. Grating pattern can be projected when the linear LED is turned on. The phase of the projected grating on the object can be shifted with changing the position of lighted linear LED easily and quickly. Authors call this method a light source stepping method. In this paper, a linear LED grating projector is developed. The characteristic of the linear LED grating projector such as the wavelength, directional characteristics, response are evaluated. The results show that this projector is useful for high-speed shape measurement. © 2013 SPIE.

DOI

Trigger Mechanism Using Interferometer for Displacement Measurement Device by Phase-Shifting Digital Holography

Otsuka, N., Riku N., Fujigaki, M. and Murata, Y.

Journal of the Japanese Society for Experimental Mechanics Vol. 13 S178-183 2013 [Refereed]

Error Reduction Method with Two Cameras on Shape Measurement Using Whole-Space Tabulation Method

Shima, A., Fujigaki, M. and Murata, Y.

Journal of the Japanese Society for Experimental Mechanics Vol. 13 S184-188 2013 [Refereed]

High-speed 3D Shape Measurement by Light Source Stepping Method Using Linear LED Device

Fujigaki Motoharu, Oura Yohei, Murata Yorinobu

Proceedings of JSPE Semestrial Meeting ( The Japan Society for Precision Engineering ) 2012 473 - 474 2012

機械的に動作する部分がなく，小型で高速な格子投影装置が実現できるライン状LEDを用いた光源切替位相シフト法をこれまでに提案してきた．LED光源の点灯位置を切り替えることで容易に位相シフトを行うことができる手法であり，全空間テーブル化手法を用いることで精度よく三次元形状計測が得られることを確認している．本研究では，実際に高速にLED光源を切り替えることで三次元形状が取得できることを示す．

DOI

Development of Shape Measurement System Using Mirrors for Metallic Objects

Fujigaki, M., Matsumoto, S., Masaya, A., Morimoto, Y., and Murata, Y.

Journal of the Japanese Society for Experimental Mechanics Vol. 12 S194-197 2012 [Refereed]

Application of an Acoustoelastic Stress Measurement System Using Grazing SH-wave to Angle Steel Construction

Y. Murata, Y. Hashimoto, M. Ikeshita, M. Fujigaki and H. Toda

Journal of the Japanese Society for Experimental Mechanics Vol. 12 S188-S193 2012 [Refereed]

ラム波による配管内壁付着厚さ測定

渡辺圭,岩橋茂雄,戸田裕己,村田頼信

超音波TECHNO 22(6) 37-42 2010

鋼構造物における非破壊応力測定方法に関する開発研究

三皷晃,村田頼信,芥川真一

電力土木 349 75-79 2010 [Refereed]

関西電力が管理するダム洪水吐ゲートは全 292 門あり,これらゲートは定期的に調査し健全性を都度評価しているが,その調査で一定の管理水準を超えた場合には,水門扉に実際に作用する応力測定等を行い再評価を実施している。しかしながら,従来手法による実応力測定では水圧荷重による発生応力のみの測定である。部材ならびに構成品を整形する時点で発生する「不整合応力」の測定は,全発生応力に占める「不整合応力」の影響を定量的に把握するためには不可欠であるものの,構造物の解体(測定場の切出し)が必要であるほか,これまで「不整合応力」を非破壊的に測定・評価する実用的な装置は広く用いられていないのが現状である。そこで今回研究では,「不整合応力」を通じ,応力状態を非破壊的に測定する新技術として『音弾性法』および『磁歪法』を活用した土木鋼構造物の応力測定手法の検討を行った。以下,その概要を紹介する。

表面SH波音弾性による圧延鋼板部材の残留応力測定

村田頼信,戸田裕己,岩崎重一

超音波TECHNO 22(6) 25-30 - 324 2010

ラム波による配管内面汚れ付着層の厚さ測定

戸田裕己,渡辺圭,村田頼信,井口博文

非破壊検査 58巻, 11号 492-498 2009.11 [Refereed]

汚れ付着配管中のラム波に関する付着材料の減衰を考慮した理論解析

戸田裕己,渡辺圭,村田頼信,岩橋茂雄

非破壊検査 58巻, 11号 499-504 2009.11 [Refereed]

Basic Study of Water-cement Ratio Evaluation for Fresh Mortar Using an Ultrasonic Measurement Technique

H. H. Ismail and Y. Murata

NDT Driving Industry Safety, Growth and Performance 90-97 2009 [Refereed]

広帯域高分子圧電探触子の超音波非線形性計測への適用

村田頼信

検査技術 ( 日本工業出版 ) 13(8) ( 8 ) 32-37 - 37 2008

音弾性によるロングレール軸応力測定 -改良型装置による新敷設レールの軸応力の経月変化測定-

戸田裕己、村田頼信、小玉尊守

非破壊検査 ( 日本非破壊検査協会 ) Vo.57(9) ( 9 ) 441-447 - 447 2008 [Refereed]

Evaluation of rolling fatigue damage in deep groove ball bearings by divided-type focusing ultrasonic transducer

Yorinobu Murata, Hiroki Toda, Chiaki Tawa, Masahiro Kiji, Noriyasu Oguma

Materials Transactions 48 ( 6 ) 1254 - 1259 2007.06 [Refereed]

To evaluate quantitatively the damage caused by rolling fatigue in deep groove ball bearings, we used a method in which the wave velocity of a leaky surface acoustic wave (SAW) propagating on the race surface of bearings was measured. The wave velocity was directly measured from the change in the propagation time by defocusing a focusing ultrasonic transducer. A new focusing ultrasonic transducer was developed by molding a piezoelectric copolymer into a concave-shaped film. To fabricate ultrasonic transducers with a lower frequency characteristic, the films were stacked and composite backings made from epoxy resin and tungsten were used. The electrode of the transducer was divided into three areas to receive direct reflection waves and leaky SAW independently without any interference. Two of these electrodes were used for the excitation and reception of leaky SAW, and the shape of the electrodes was designed so that leaky SAW might propagate only on the raceway surface of the inner ring of the bearings. Moreover, in order to suppress the effects caused by edge waves, the shape of the electrodes for leaky SAW was considered. The availability of this method was evaluated by measuring the leaky SAW velocity in the bearings whose worked hours differed. As a result, a small difference in leaky SAW velocity was detected according to the worked hours of the bearings, and it was demonstrated that this method would be useful for non-destructive soundness evaluation of bearings. ©2007 The Japanese Society for Non-Destructive Inspection.

DOI

超音波による配管内面の汚れ計測技術

森貞重男, 井口博文, 戸田裕己, 村田頼信, 渡辺圭

検査技術 ( 日本工業出版 ) vol.9(3) ( 3 ) 14-19 - 19 2004 [Refereed]

Basic Study on Estimation for Water-Cement Ratio of Fresh Concrete

Y. Murata, H. Toda, K. Futagami and K. Sumikawa

Key Engineering Materials Vols.270-273, Part-2 1580-1585 2004 [Refereed]

コンクリートの強度を左右する水セメント比を施工前に簡便かつ迅速に測定するために,フレッシュコンクリートの水セメント比を超音波によって推定することを試みた.これは,広帯域超音波トランスデューサを用いて透過法により実現した.水セメント比45～65%のフレッシュコンクリートについて,混合後の超音波音速の変化を測定した.その結果,水セメント比の違いによって超音波音速が異なることを確認した.また,透過超音波の周波数スペクトルから水セメント比を推定することを試みた.その結果,混合後の時間にかかわらず,再練り直後の周波数スペクトルと水セメント比に相関性を見いだした.これにより,混合後の時間が未知の場合でも,周波数スペクトルから水セメント比を推定可能であることを実証した.

Development of a focused ultrasonic transducer for the testing of the wheel seat in the hollow axle of Shinkansen vehicles

Yorinobu Murata, Hiroki Toda, Masataka Ikeda, Yoshiyuki Nil, Jiro Yohso

American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP 484 103 - 110 2004 [Refereed]

In order to test the fretting fatigue cracks with high sensitivity, which occurred on the wheel seat of hollow axles of Shinkansen vehicles, the design of a focused ultrasonic transducer was proposed by a new method. The method was achieved by designing a suitable surface shape of the ultrasonic transducer through a reverse analysis of the wave propagation in the axle so that all radiated waves from the transducer were focused into a point region of the wheel seat with a same phase. A composite piezoelectric material was applied to the focused ultrasonic transducers in order to test with a shorter ultrasonic pulse. As the result of evaluating the performance of the developed focused ultrasound transducer, comparing with the previous plate-like ultrasonic transducer made using PZT, a great improvement was demonstrated in respect of sensitivity and directivity. Furthermore, the method inclining the ultrasonic beam slightly to the circumference direction and the method making the frequency characteristic of the transducer high were devised in order to reduce the influence of echoes by press fit. Consequently, it was demonstrated that a focused incline ultrasonic transducer of 10 MHz was possible to evaluate up to an artificial crack of about 0.17 mm depth with the SN ratio of 9 dB.

DOI

波形整形法を用いた表面SH波法によるフレッチング疲労き裂の定量評価

村田頼信,谷本晃久,戸田裕己

非破壊検査 ( 日本非破壊検査協会 ) Vol.52(11) ( 11 ) 620-627 - 627 2003.11 [Refereed]

新幹線鉄道輪軸の検査において,フレッチング疲労き裂の進展状態を非解体で定量評価するために,波形整形法を用いた表面SH波探傷法を提案した。実体車軸から切出した試験片の人工きずを探傷することによって波形整形法の有効性を評価した。その結果,波形整形法は探傷エコーのリンギングを大幅に低減させ,より高い距離分解能での超音波探傷を実現した.また,波形整形法は人工きずの上下端からの端部エコーを分離して検出することを可能にした.この人工きずの端部エコーの時間差から人工きずの高さを評価した.さらに,軸方向に沿って探触子をシフトして探傷することによって,人工きずの高さだけでなく傾き角も同時に評価した.その結果,正確なきず高さと傾き角の評価が可能となり,本研究で提案する方法が車軸の探傷に非常に有用であることを実証した.

Optimal Wavelength Pair Selection and Accuracy Analysis of Dual Fiber Grating Sensors for Simultaneously Measuring Strain and Temperature

Ponniah Sivanesan, James S. Sirkis, Y. Murata, Steven G. Buckley

Optical Engineering 41 (10) 2456-2463 2002.10 [Refereed]

温度および歪みを計測するためのデュアルファイバグレーティングセンサの波長選択性について検討した.波長の範囲は600～1600nmとした.理論値はGhoshの温度依存係数モデルを光ファイバガラスに適用することによって求めた.また,表面接合されたファイバグレーティングセンサの熱係数を考慮に入れ,構造的な熱膨張による見かけ上の熱歪みの効果を調べた.そして,そのときの温度と歪みの測定精度を数学的に導き出した.以上の結果,構造的な温度特性がデュアルグレーティングセンサの測定精度と分解能に大きく影響することを明らかにした.

超音波によるPE管EF継手融着面の健全性評価

戸田裕己,北岡利道,井上富美夫,村田頼信,吉田乙雄,古川浄治

非破壊検査 Vol.50(12) ( 12 ) 789-797 - 789 2001.12 [Refereed]

PE(ポリエチレン)製ガス管EF(Electrofusion)継手部に泥水が混入した場合の欠陥検出にていて検討を行った.高分子製の集束超音波トランスデューサを検査に適用し高感度な測定を試みた.その結果,従来のPZT製超音波トランスデューサに比べ広帯域な超音波パルスでの探傷が可能となり,泥水混入時にできる気泡欠陥に対しφ0.5mmの大きさのものまで検出できることがわかった.また,融着熱が超音波計測に与える影響について調べた結果,融着後30分以内の探傷は欠陥を誤認する恐れがあることがわかった.さらに,Bスコープ画像として融着部を表示することを行い,欠陥検出がより明確にかつ容易に行えることを示した.

Generation of an enhanced acoustic streaming in a bounded space

Y Murata, S Kimura, S Takei, K Minagawa, J Takimoto, K Koyama

JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA ( AMER INST PHYSICS ) 102 ( 5 ) 2536 - 2538 1997.11 [Refereed]

A procedure to generate enhanced acoustic streaming into a bounded space has been studied. Under continuous ultrasound radiation, it was difficult to generate enhanced acoustic streaming in bounded space because of disturbances by reflected waves. Efforts were made to remove the disturbances by adjusting the repeat time of tone bursts of ultrasound. An experimental system has been developed for visualizing acoustic streaming. As a consequence of experiments, the streaming velocity in the bounded space has been enhanced by about 2.5 times by using a series of tone bursts of ultrasound. (C) 1997 Acoustical Society of America.

Basic study of particle characterization using the ultrasonic finite amplitude method

H. Ootaki, Y. Murata, K. Minagawa, K. Koyama

Journal of Materials Science Letters ( Kluwer Academic Publishers ) 14 ( 3 ) 182 - 184 1995.01 [Refereed]

材料内部の分散構造と超音波非線形性との相関を明らかにするために,液体(シリコーンオイル)中に球状粒子(ポリスチレンやイオン交換樹脂など)を分散させ,粒子径および粒子濃度と超音波非線形との関係を調べた.その結果,粒子径が送信波の波長に近いと非線形性は増大し,半波長に近い,つまり2次高調波の波長に近いと非線形性が減少することがわかった.また,粒子濃度に依存して非線形性が増大した.粒子分散系では分散媒中で発生した2次高調波の散乱を考慮することでこれらの非線形現象のメカニズムが説明できることを示した.

DOI

Mixing of Phase-separated Polymeric Liquids by Ultrasonic Radiation

K. Murai, S. Muto, Y. Murata, K. Minagawa, J. Takimoto and K. Koyama

Rep. Prog. Polym. Phys. Jpn., Vol.38 75-76 1995 [Refereed]

セル内で局所的な混合や化学反応を起こすための基礎的検討として,2層分離した高分子液体を超音波放射により局所的に攪拌することを試みた.集束型超音波トランスデューサを用いて超音波を集束させることにより,局所的に超音波の放射圧を大きくした.容器内に2層分離液体とトレーサーを入れ攪拌の様子を観察することで最適な攪拌条件を調べた.その結果,容器の形状や2層液体の比率によって,容器内に発生する流動の速度に違いを見いだした.なおかつ,超音波の放射パターンを印加電圧波形で制御することで局所的な攪拌が行えることを明らかにした.

超音波照射による金型内高分子溶融体の流動

村田頼信,木村智,南川慶二,滝本淳一,小山清人

成形加工, 7(9) 563-567 1995 [Refereed]

プラスチック製品を射出成形で加工する時に問題となっているウエルドラインの発生を超音波流動によって抑えることを提案した.基礎実験として,エチレン-酢酸ビニル共重合体を溶融させ金型外から効率よく超音波流動を発生させることを試みた.溶融したプラスチックの可視化は,円盤状に加工した試料表面を着色し,それを積み重ねたものを円筒金型内で溶融することによって実現した.結果として,金型外から超音波流動を発生させることに成功し,超音波トランスデューサに印加する電圧信号のパターンにより,流動の強さが変化することを示した.

水の超音波分解における超音波照射強度の影響

柳田裕隆, 村田頼信, 南川慶二, 滝本淳一, 尾形健明, 小山清人

ソノケミストリー討論会講演論文集 ( 日本ソノケミストリー学会 ) 4 9 - 11 1995

DOI

Design of an acoustical imaging operator based on the singular value decomposition method

Yorinobu Murata, Keiji Minagawa, Yasutaka Tamura, Kiyohito Koyama

Japanese Journal of Applied Physics 33 ( 5S ) 3176 - 3180 1994 [Refereed]

A new imaging operator has been developed for acoustical imaging using a 2ch m-sequence encoding array transducer. The new imaging operator has the ability to correct the poor orthogonal property of a transfer matrix. Moreover, images with many image points have been reconstructed by the new imaging operator. The new imaging operator has been composed on the basis of the singular-value decomposition (SVD) of the transfer matrix in the frequency domain. Characteristics of the new imaging operator are discussed by simulating the two-dimensional point spread functions (2-D PSFs). An image with a high dynamic range was obtained for a single object on the sampling image points by the method. Moreover, the method was able to reconstruct the image of the existing object outside the sampling image points. © 1994 The Japan Society of Applied Physics.

DOI

Acoustic Nonlinear Characteristics of Nylon Fiber

H. Otaki, Y. Murata, K. Minagawa and K. Koyama

Rep. Prog. Polym. Phys. Jpn., Vol.37 347-348 1994 [Refereed]

超音波非線形計測を非破壊による内部構造評価へ応用するため,その基礎研究として繊維構造と超音波非線形性の関係を明らかにすることを試みた.試料として繊維径の異なるナイロン6繊維を鉄フレームに巻いたものを作製し,これを水中に入れ,繊維部分のみに超音波を透過させた.音速と超音波非線形性を測定した結果,繊維量が同じであるにもかかわらず,繊維径が大きくなるに従って音速が速くなることが分かった.また,非線形性は繊維径と超音波波長との比によって変化することがわかった.

Basic Study for Generation of Acoustic Streaming in Bounded Field

Y. Murata, S. Kimura, S. Takei, K. Minagawa and K. Koyama

Rep. Prog. Polym. Phys. Jpn., Vol.37 51-54 1994 [Refereed]

超音波流動を有限領域内で効率よく発生させて攪拌に応用するための基礎的な検討を行った.超音波流動を可視化するために,円筒形のセルにシリコーンオイルを満たし,その中に高密度ポリエチレン粉末を分散させた.連続超音波を照射して流動の様子を観察した結果,領域内で発生する多重反射が流動の方向や強さに大きく影響を与えることがわかった.セル内に効率的に超音波流動を発生させるためには,断続的な信号で超音波トランスデューサを印加し,多重反射の影響を取り除く必要があることが分かった.

Acoustic Nonlinearity in Polymer Film

S. Muto, H. Otaki, Y. Murata, K. Minagawa and K. Koyama

Rep. Prog. Polym. Phys. Jpn., Vol.37 349-350 1994 [Refereed]

高分子フィルムの結晶化度を評価する一つの方法として超音波非線形測定を提案した.試料として,結晶化度の異なるPP(ポリプロピレン)フィルム(65mm×90mm)を用いた.これを精製水中に入れ,超音波の入射角を変化させながら,高調波成分と基本波成分とを比較する有限波振幅法により超音波非線形性を測定した.その結果,結晶化度の増加に伴って超音波非線形性が顕著に変化すること示した.さらに,高分子フィルムに超音波が入射する角度によって超音波非線形性が変化することを見出した.

2-ch M-sequence Encoding Array Transducer System for Acoustical Imaging

Y. Murata, Y. Tamura and K. Koyama

Acoustical Imaging Vol.20 379-386 1993 [Refereed]

送信子を中心とした対称にM系列の符号化受信開口を2つ用いることにより空間選択性の改善を試みた.また,イメージングエリアを格子点で離散化したモデルをとりあげ,相関法による水中での映像再生を試みた.相関法における像再生オペレータはコンピュータを用いてより細かい格子点(512×512)で構成した.このオペレータに受信波形を作用させて8mm×8mmのエリアの画像化を行った結果,1回の送受信のみで点物体ターゲットの存在を確認することができた.このときの分解能は,水平方向で0.20mm,深さ方向で0.12mmであることを実証した.

ACOUSTICAL IMAGING USING M-SEQUENCE ENCODING ARRAY TRANSDUCER

K KOYAMA, Y MURATA, K TANAKA, Y TAMURA

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS ( JAPAN J APPLIED PHYSICS ) 30 152 - 155 1991 [Refereed]

An experimental study on an ultrasonic camera has been carried out using a pair of m-sequence encoding transducer made of VDF-TrFE copolymer. The ultrasonic camera can construct an image without mechanical or electrical scanning. The transducer must have wide-band characteristics. The system operates at the frequency of 10 MHz. A two dimensional point spread function of the camera system was calculated by both the correlation procedure and the pseudo-inversion matrix method, and the results were compared with the previous encoding aperture receiver system.

列車通過時における鉄道橋の動的な変位計測へのサンプリングモアレカメラの適用

藤垣元治,原卓也,生駒昇,村田頼信

実験力学 Vol.12, No.3 35-40 1905 [Refereed]

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