中文摘要：

针对波源对纵向模态导波在管道中传播的影响问题,建立改进的管道纵向模态导波半解析有限元（Semi-analytical finite element,SAFE）模型,相对先前的SAFE模型,实现纵向模态导波的单独计算求解,提高了计算效率。在此基础上,利用正交模态展开法建立波源对纵向模态导波在管道中传播影响的数学模型,分析数学模型可以看到纵向模态导波的幅值取决于导波的波结构和波源特性。为论证波源对纵向模态导波在管道中传播影响的数学模型,通过数值计算和试验方法,从相同波源激励的不同纵向模态导波之间的幅值关系和不同波源激励的同一模态导波之间的幅值关系两个方面开展研究工作。对比数值计算结果和试验结果,说明建立的波源对纵向模态导波在管道中传播影响的数学模型是可信的。研究结论为设计合适的导波传感器实现在管道中激励特定的纵向模态导波奠定了基础。

英文摘要：

The improved semi-analytical finite element（SAFE） model for longitudinal mode guided waves in pipeline is built to research the source influence on longitudinal mode guided waves. Comparing with previous SAFE models, the improved SAFE model can compute longitudinal mode guided waves independently, which significantly improves the computational efficiency. The mathematical model for source influence on longitudinal mode guided waves is built based on the normal mode expansion technique. The model shows the amplitudes of longitudinal mode guided waves depend on the wave structures of guided waves and the characteristics of sources. The numerical calculations and experiments are done to research two questions, one is the amplitude relationships of different longitudinal mode guided waves excited by the same source, the other one is the amplitude relationships of a certain mode longitudinal mode guided wave excited by different sources. The experimental results accord with numerical ones, which shows the correctness of the mathematical model. The conclusions lay the foundations for exciting a certain longitudinal mode guided wave in pipeline by designing suitable transducers.