Damage Evaluation of Structural Components by Ultrasonic Attenuation
Project/Area Number  08650560 
Research Category 
GrantinAid for Scientific Research (C)

Section  一般 
Research Field 
構造工学・地震工学

Research Institution  Tohoku University 
Principal Investigator 
KITAHARA Michihiro Tohoku University, Dept.of Civil Engineering, Professor, 大学院・工学研究科, 教授 (60135522)

Project Fiscal Year 
1996 – 1997

Project Status 
Completed(Fiscal Year 1997)

Budget Amount *help 
¥2,000,000 (Direct Cost : ¥2,000,000)
Fiscal Year 1997 : ¥1,000,000 (Direct Cost : ¥1,000,000)
Fiscal Year 1996 : ¥1,000,000 (Direct Cost : ¥1,000,000)

Keywords  Scattering crosssection / Attenuation / Crack / Ultrasonics / Elastodynamic scattering / 弾性散乱断面積 / 散乱減衰 / クラック / 超音波 / 三次元弾性散乱 
Research Abstract 
The results of the study are summarized as follows. 1.The boundary integral equation to determine crack opening displacements was formulated for scattering problems of a crack in three dimensional elastic solids. The quarter point elements were introduced for the crack tip and the regularization was performed for the hyper singular kernel of the boundary integral equation. 2.Farfield expressions of longitudinal and transverse scattering amplitudes were obtained from the threedimensional elastodynamic Green's function. Then the expression of elastodynamic scattering crosssections was formulated from the farfield scattering amplitudes. 3.The angular distributions of differential scattering crosssections were numerically calculated and the frequency characteristics of the elastodynamic scattering crosssection were investigated. It was found that the longitudinal part of the differential scattering crosssection is localized to the propagation direction of the incident wave when the frequency increases. The total scattering cross section has a peak when the wavelength of the incident wave becomes the order of crack diameter. 4.The relation of elastodynamic scattering crosssection, attenuation and crack density was obtained from the assumption of the dilute distribution of cracks in structural components. It was proposed to estimate the crack density by measuring the attenuation in damaged components.

Report
(4results)
Research Output
(14results)