边界元中的边界积分计算直接影响问题的求解精度和计算速度。边界积分计算分为奇异积分和非奇异积分。奇异积分一般采用精确积发，非奇异积分采用Guass数值积分，当配置点接近积分单元时，非奇异积分计算精度将降低，采用积分区域变换，将三维重调和方程的二维积分化为一维积分，这样将奇异积分和非奇异积采用精确积分的方法计算，使求解精度、计算速度都得到提高。

The boundary integral in Boundary Element Method effects the precision and the speed of the method. The boundary integrals are composed of the normal integrals and singular integrals. The normal integrals are popularly calculated by exact integral, and the singular integrals by the Gauss numerical integral. The singular integrals are low in precision when the source points approach the element. This paper presents an alternative way to transform the double integral in Biharmonic Equation on 3-d into the linear integrals on the boundary of each subdomain, so that all the singular integrals and nonsingular integrals are calculated by analytical method. It makes the precision and the speed of BEM improve.

O172.2

国家自然科学基金资助课题 (19171197)