Analysis of Elastodynamic Behavior of Leisure Medium with Two Cavities -In Ligneous Medium Cases

• Main Authors: Shag-Han Tsai, 蔡尚翰
• Other Authors: Deng-Ching Wong
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/89578x

碩士 === 台灣首府大學 === 休閒管理學系碩士班 === 100 === The interaction of two scatterers (cavities) with harmonic elastic waves in a two dimensional infinite anisotropic medium is investigated in this paper. The adopted incident waves in the paper are quasi-P and quasi-SV waves. To solve the scattering problems, the boundary integral equations (BIEs) are first formulated by using Betti-Rayleigh reciprocal theorem and fundamental solution in time-harmonic domain of an infinite anisotropic medium. Then employing the boundary element method with appropriate boundary conditions, the BIEs above mentioned are transformed into one set of linear simultaneous equations and numerically solved. The numerical validation was worked with the correspondingly scattering problems of isotropic cases. Numerical results of the scattering displacements on the boundaries of cavities were present. The influence of the sizes of cavities and the distance between two cavities on scattering displacements were analyzed and discussed. In addition, the interactional conditions of circular and elliptic (approximate crack condition) cavities was also discussed. The analytic results of the scattering problems are helpful to NDT of composite materials. The variations of boundary displacements of first cavity were discussed under four different conditions in this paper. In the first case for fixing the distance between the two cavities and the first cavity radius and changing the second cavity radius, the effect for the boundary displacements of the first cavity was greater when the radius of the second cavity was greater. In the second case for fixing two cavities sizes and changing the distances between two cavities, it was presented the greater effect for first cavity when the distance between two cavities was shorter. The third case for fixing size and distance of the two cavities and changing conditions of the incident wave numbers, it was found the influence of the interaction between the two cavities was greater when the incident wave number was bigger. The fourth case for keeping circle shape of the first cavity and degrading the second cavity to be elliptical shape, the significant influence was found for the second cavity shapes on scattering displacements of the first cavity, and the stress concentration at point of the first cavity closest to the second elliptical cavity there was significant change with the short axis change of the second cavity