本文應用耦合有限元素法與邊界積分式探討結構體與流體互制作用在三維聲場的分析，單獨使用有限元素法對無限域聲場作離散，需要輸入龐大的資料，而且大型矩陣的計算相當費時。故一般分析外部聲場的結構體與流體互制作用所採用的方法以邊界元素法居多，但是邊界積分方程場點的選擇與源點重合，會產生奇異性積分問題增加計算的困難度。本文耦合有限元素法與邊界積分式避免了上述的問題，結構體與部份流體以有限元素分割，結構體與流體接觸的界面及流體外部的邊界以邊界元素分割，最後將耦合有限元素法與邊界積分式應用在三維聲場的放射和散射問題中，與解析解相比十分一致，證明此數值方法的可靠性。

This study presents the application of the coupled Finite Element Method (FEM) and Boundary Integral Equation (BIE) to determine the three dimensional fluid-structure interaction problems.
It is very complex to discrete the infinite space and needs a large of data and time to compute exterior acoustic field by Finite Element Method.
In general,
analysis of the fluid-structure interaction in the exterior acoustic potential field uses the Boundary Element Method (BEM).
It creates difficulty of compute that the singularity exists when the source point and the field point are the same point by using Boundary Integral Equation.
This paper adopts the coupled Finite Element Method and Boundary Integral Equation to avoid above difficulties.
Twenty-noded isoparametric quadrilateral element is used to discrete the finite region,
and the boundary using eight-noded isoparametric element.
Finally,
applying the coupled Finite Element Method and Boundary Integral Equation in three dimension be acoustic radiation and scattering problems,
the results we got are shown to be very accurate compared with the analytical solutions.
It proves the reliability of the numerical method.

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