中文摘要：

研究超声导波在复杂结构中的传播或与复杂缺陷的交互作用时，常需要对其传播过程进行有限元仿真．建立吸收边界抑制边界回波的影响是仿真中的关键问题．在三维模型中实现了阻尼递增吸收边界设置方法，该方法通过改变材料阻尼系数来有效抑制边界回波．对吸收边界的尺寸、阻尼系数选取等问题进行了研究，发现吸收边界尺寸为主要影响因素，其长度需大于2A才可有效衰减超声导波．本模型应用于求解缺陷散射矩阵，验证了此吸收边界设置方法的有效性．

英文摘要：

Finite element method （FEM） is normally used to study guided wave propagating in complex structure and the scattering field in defects. A key problem in FEM is to set the absorbing region to reduce the reflection from boundary. A method by changing the damping coefficient of material to achieve absorbing boundary in a 3D model is realized, and it is also discussed how to choose parameters such as layer number and damping. Results show that the size of the absorbing boundary is the main influencing factor, and the length should be longer than two wavelengths. To prove its validity, this model was applied to calculating scattering matrix of defects.