APPLICATION TO STRUCTURAL ANALYSIS OF ESPI,HOLOGRAPHY AND 3D SHAPE MEASUREMENT

Nagasaki University, Graduate School

Yasuaki SUGIHARA

Tomofumi NAKYAJIMA

Masataka MORI

Nagasaki University

Naoki MATSUYAMA

Hiroshi MATSUDA

■The measurement method is easy, and precision is high■Now the strain measurement method spreading most widely

Problems

Measurement at a contact-type and fixed point

■Measurement only for gauge pasting point■Use limit by environment, amount of strain, and fatigue

It is necessity of non contact and full field measurement

Strain gauge method

Introduction

・ Three dimensional shape measurement・ Holography interferometry measurement・ Electronic Speckle Pattern Interferometry(ESPI) measurement

Three dimensional shape measuring system

Three dimensional shape measuring system

Feature

3D coordinates of the object can be measured

・ Portable and generality are abundant・ Measurement time is short

The shape of Concrete Joint and Nagasaki Peaceful Prayer was measured

Shape measurement of Concrete Joint

Concrete Joint 3D shape data

Detailed 3D coordinates of Concrete Joint surface was obtained

3D shape measurement of Nagasaki Peaceful Prayer

From 8 directions

Point group data Shape data

Shape data is obtained by connecting point group data, and pasting surface

Detailed 3D coordinates of Nagasaki Peaceful Prayer surface was obtained

Holographic interferometry measuring system

Measurement of small deformation and vibration are possible by obtaining interference fringes

・ Measurement time is short・ Measurement in darkroom

The vibration of Twisted Conical Shells and Notched Specimen was measured

Holographic interferometry measuring system

Feature

Free vibration modes of Twisted Conical Shells

Specimen FE analysisHolography

Mode of vibration

Frequencies and modes of vibration almost agree with the FE analytical results

8th mode 3289(Hz) 3522(Hz)

Vibration modes of the Notched Specimen

Holography

Mode of vibration

Frequencies and modes of vibration almost agree with the FE analytical results

FE analysis

3rd mode 　 520(Hz) 538(Hz)

ESPI measuring system

・ Measurement under visible light is possible・ Non contact and full field measurement

From an interference fringe of speckle provided by interference of a laser, measurement of displacement of an object is possible

Electric Speckle Pattern Interferometry (ESPI) measuring system

Feature

The displacement of Tensioned membrane and Defective Plate was measured

Wrinkle measurement of Tensioned membrane

Wrinkle Distribution of a minor principal strain

Research of membrane structure Specific in time and the place of the wrinkle generation is necessary

ESPI measuring system enables specific in the wrinkle generation part

Tensile Test of the Defective Plate

Specimen

Load - Maximum principal strain curve

The concentration of the strain was able to be confirmed to the vicinity of the breaking side at the small load level by ESPI measuring system

Strain (μ)

Loa

d (N

)

Summary

Application of optical measurement technology to structure

APPLICATION TO STRUCTURAL ANALYSIS

・ Information that was not able to be seen by eyes can be acquired

・ Enormous 3D coordinate information can be acquired in a short time

ESPIの原理

変位 u に対する位相差の増分 Δφ

Δφ ＝ sinθ４ πuλ

光学系

CCD カメラ

レーザー光

レンズ対象物

θ

Δφ が２ π 変化するごとに干渉縞が１本発生する

干渉縞u

スペックルパターン

Principle of ESPI

Increment of phase difference Δφ to displacement u

Δφ ＝ sinθ４ πuλ

Optical system

CCD

laser beams

lensobject

θ

Δφ が２ π 変化するごとに干渉縞が１本発生する

Interference 　fringes

u

Speckle pattern

Electric Speckle Pattern Interferometry(ESPI) measuring system

長崎平和祈念像の形状計測

変位分布 応力分布