論文 - 村田　頼信

鉄道ロングレールの軸応力測定に対する表面SH波音弾性の適用

村田頼信, 宮崎秀史, 松丸和貴, 千代誠, 藤垣元治 (担当区分： 筆頭著者,　責任著者 )

実験力学 ( 日本実験力学会 )  16 ( 1 ) 47 - 52   2016年04月  [査読有り]

　概要を見る

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

サンプリングモアレ法による動的たわみ角分布計測

藤垣元治, 冨田大樹, 村田頼信

実験力学 ( 日本実験力学会 )  15 ( 4 ) 315 - 319   2015年12月  [査読有り]

格子投影法を用いた高さ測定装置における計測精度予測手法の提案

金子健太郎, 藤垣元治, 村田頼信

実験力学 ( The Japanese Society for Experimental Mechanics )  15 ( 3 ) 210 - 216   2015年09月  [査読有り]

　概要を見る

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年08月  [査読有り]

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年08月  [査読有り]

Prototype of a Handheld Displacement Measurement System Using Multiple Imaging Sensors

M. Fujigaki, H. Minamino, N. Ikoma, H. Tamai and Y. Murata (担当区分： 最終著者 )

Journal of JSEM   15   S70 - 74   2015年07月  [査読有り]

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年  [査読有り]

　概要を見る

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年  [査読有り]

　概要を見る

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年10月  [査読有り]

　概要を見る

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

複数撮像素子を用いた位相シフトデジタルホログラフィによる小型ひずみ計測装置の試作

藤垣 元治, 南野 宏紀, 村田 頼信

精密工学会学術講演会講演論文集 ( 公益社団法人 精密工学会 )  2013   421 - 422   2013年

　概要を見る

橋梁や鉄塔などの鋼構造物の内部欠陥の検査を行うために，デジタルホログラフィによるひずみ分布計測システムの開発を行い，小型化のために複数の撮像素子を用いることで入射光を１光束にして光学系を簡略化する手法を提案している．本研究では，その手法を用いた小型計測装置の試作を行う．

DOI

ラインLEDデバイスによる三次元形状計測装置の小型化および精度評価

坂口 俊雅, 藤垣 元治, 村田 頼信

精密工学会学術講演会講演論文集 ( 公益社団法人 精密工学会 )  2013   425 - 426   2013年

　概要を見る

近年，既存の装置に組み込むことができる高精度でコンパクトな形状計測装置が産業界で求められている．これらのニーズを満たすため本研究室ではラインLEDデバイスを開発した．このデバイスは LED素子を直線上に複数列に配置し，その点灯位置を切り替えることにより投影格子のシフトを行うデバイスである．本研究ではラインLEDデバイスを用いることで形状計測装置の小型化を行い，開発した装置の精度評価を行った．

DOI

格子投影による形状計測における対称に配置されたプロジェクター2台を用いた精度向上手法の提案

島 淳, 藤垣 元治, 村田 頼信

精密工学会学術講演会講演論文集 ( 公益社団法人 精密工学会 )  2013   429 - 430   2013年

　概要を見る

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年  [査読有り]

　概要を見る

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年  [査読有り]

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年  [査読有り]

LEDを用いた光源切替位相シフト法による高速度三次元形状計測

藤垣 元治, 小浦 洋平, 村田 頼信

精密工学会学術講演会講演論文集 ( 公益社団法人 精密工学会 )  2012   473 - 474   2012年

　概要を見る

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年  [査読有り]

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年  [査読有り]

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年

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年  [査読有り]

　概要を見る

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。