Structural finite element coupled with the conjugated infinite element method is an efficient numerical technique for solving the acoustic radiation problem due to the vibration of underwater objects. However, for large complex structures, the total acoustic mesh would become very large if the artificial boundary is too far away from the structural wetted surface. Thus, the calculation time can become too long to confine the application of the conjugated infinite element method. On the other hand, if the artificial boundary is close to the structural wetted surface, it will lead to computation accuracy losing due to the near-field effects. Consequently, it is essential to present some guidelines based on the physical mechanism of structural acoustics to choose a suitable artificial boundary that optimizes calculation accuracy and efficiency. In present work, the evanescent wave theory of an infinite length cylindrical shell is adopted to theoretically analyze the decay characteristic of evanescent waves in near field. Then, the effect of the position of artificial boundary on computation accuracy of conjugated infinite element for a finite length ring-stiffened cylindrical shell is numerically investigated. Results suggested that for the cylindrical shell mentioned in this study, the artificial boundary can be placed at least 0.4 times the acoustic wavelength away from the structural wetted surface. What’s more, for high frequencies or large-scale structures, the required non-dimensional distance between the artificial boundary and the structural wetted surface increases.

结构有限元与共轭无限元法相结合是解决水下物体振动引起的声辐射问题的有效数值技术。但是，对于大型复杂结构，如果人工边界距离结构的润湿表面太远，则总的声学网格将变得非常大。因此，计算时间可能变得太长而无法限制共轭无限元法的应用。另一方面，如果人工边界靠近结构的润湿表面，则会由于近场效应而导致计算精度下降。因此，必须根据结构声学的物理机制提出一些准则，以选择合适的人工边界，以优化计算精度和效率。在目前的工作中，采用了无限长圆柱壳的van逝波理论来对analyze逝波在近场中的衰减特性进行理论分析。然后，数值研究了有限长环加劲圆柱壳上人工边界位置对共轭无限元计算精度的影响。结果表明，对于本研究中提到的圆柱壳，可以将人造边界放置在距结构润湿表面至少声波波长0.4倍的位置。此外，对于高频或大型结构，人造边界和结构润湿表面之间所需的无量纲距离会增加。采用无限长圆柱壳的van逝波理论对theory场在近场中的衰减特性进行了理论分析。然后，数值研究了有限长环加劲圆柱壳上人工边界位置对共轭无限元计算精度的影响。结果表明，对于本研究中提到的圆柱壳，可以将人造边界放置在距结构润湿表面至少声波波长0.4倍的位置。此外，对于高频或大型结构，人造边界和结构润湿表面之间所需的无量纲距离会增加。采用无限长圆柱壳的van逝波理论对theory场在近场中的衰减特性进行了理论分析。然后，数值研究了有限长环加劲圆柱壳上人工边界位置对共轭无限元计算精度的影响。结果表明，对于本研究中提到的圆柱壳，可以将人工边界放置在距结构润湿表面至少声波波长0.4倍的位置。此外，对于高频或大型结构，人造边界和结构润湿表面之间所需的无量纲距离会增加。数值研究了有限长环加劲圆柱壳人工边界位置对共轭无限元计算精度的影响。结果表明，对于本研究中提到的圆柱壳，可以将人工边界放置在距结构润湿表面至少声波波长0.4倍的位置。此外，对于高频或大型结构，人造边界和结构润湿表面之间所需的无量纲距离会增加。数值研究了有限长环加劲圆柱壳人工边界位置对共轭无限元计算精度的影响。结果表明，对于本研究中提到的圆柱壳，可以将人工边界放置在距结构润湿表面至少声波波长0.4倍的位置。此外，对于高频或大型结构，人造边界和结构润湿表面之间所需的无量纲距离会增加。远离结构湿润表面的声波波长的4倍。此外，对于高频或大型结构，人造边界和结构润湿表面之间所需的无量纲距离会增加。远离结构湿润表面的声波波长的4倍。此外，对于高频或大型结构，人造边界和结构润湿表面之间所需的无量纲距离会增加。