Study on Rational Numerical Computation of Reflecting Energy of Elastic Waves by a Gradient Inhomogeneous Layr
Project/Area Number  06805008 
Research Category 
GrantinAid for Scientific Research (C).

Research Field 
Materials/Mechanics of materials

Research Institution  Akita University 
Principal Investigator 
OHYOSHI Tadashi Mining College, Akita University Professor, 鉱山学部, 教授 (70006691)

CoInvestigator(Kenkyūbuntansha) 
MIURA Kimihisa Mining College, Akita University Assistant, 鉱山学部, 助手 (80110667)

Project Fiscal Year 
1994 – 1995

Project Status 
Completed(Fiscal Year 1995)

Budget Amount *help 
¥1,600,000 (Direct Cost : ¥1,600,000)
Fiscal Year 1995 : ¥300,000 (Direct Cost : ¥300,000)
Fiscal Year 1994 : ¥1,300,000 (Direct Cost : ¥1,300,000)

Keywords  Elastic Wave / Gradient Inhomogeneous Layr / Reflection / Computation / SH wave / Acoustic Impedance / Transfer Matrix / Linear Inhomogeneous Layr Element / 弾性波 / 傾斜不均質 / 反射 / 積層 / 不均質層要素 / 計算 / 音響インピーダンス / 伝達マトリックス / 不均質要素 / 計算法 
Research Abstract 
Studies on multiple reflection and transmission of elastic waves relating to a nondestructive inspection of inhomogeneous layrs, have been reported by many researchers. Theoretical analyzes of modern problems of functionally gradient materials are generally difficult ones without resorting to some numerical approach. Most analyzes relating to an inhomogeneous elastic layr may be classified into two kinds of approaches. One is the approximation by piling up large number of homogeneous thin layrs, which approach is likely to lead to a large amount of numerical calculations. The other approach is a theoretical analysis using restricted function to describe the inhomogeneous property inside a material. The function should be chosen so that the governing equations may have manageable solutions. To improve such the unsatisfied approaches, the fundamental new element is originally introduced in the course of this project, and named as Linear Inhomogeneous Layr Element (LILE). Stacking of the
… More
new elements may improve much the adaptability to various real inhomogeneous solids with small number of elements, because each of the LILE has individual linear variation of acoustic impedance over the thickness. The analytical formulation of the stacking multilayr structure was systematically made by the transfer matrix method. The application of the LILE stacking model, as an example, to a reflection and transmission problem of obliquely incident SHwave impinging on the gradient inhomogeneous layr, was demonstrated. The developing process of the stacking model was interpreted, and their calculated intensity of reflection can be verified by the conservation law of energy. The results show excellent adaptability of the model to an acoustic impedance variation. Benefits of such the new elements to the analysis are confirmed by comparison with conventional approximate method of piling up of many homogeneous layrs. LILE is then a viable tool for such a difficult dynamic problem of inhomogeneous material. When the layr thickness is very thin, the fundamental solutions have ill nature in their computation. This current problem should be figured out in order to increase the availability of LILE. Less

Report
(4results)
Research Output
(15results)