1995 Fiscal Year Final Research Report Summary
Study on Rational Numerical Computation of Reflecting Energy of Elastic Waves by a Gradient Inhomogeneous Layr
| Project/Area Number |
06805008
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Materials/Mechanics of materials
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| Research Institution | Akita University |
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Principal Investigator |
OHYOSHI Tadashi Mining College, Akita University Professor, 鉱山学部, 教授 (70006691)
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| Co-Investigator(Kenkyū-buntansha) |
MIURA Kimihisa Mining College, Akita University Assistant, 鉱山学部, 助手 (80110667)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Elastic Wave / Gradient Inhomogeneous Layr / Reflection / Computation / SH wave / Acoustic Impedance / Transfer Matrix / Linear Inhomogeneous Layr Element |
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| 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
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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 SH-wave 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
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Research Products
(10 results)
