为了提高水下大长径比圆柱壳低频振动响应和辐射声功率的计算效率，该文提出了一种用水下梁模型等效计算的方法。该等效模型基于欧拉梁理论，采用附加水质量近似流固耦合作用，通过计算梁的等效杨氏模量系数，使其与圆柱壳的梁式弯曲振动模态对应。计算表明，对大长径比简支圆柱薄壳（L/a＞20），等效梁杨氏模量系数主要取决于结构长径比，而厚度对其的影响甚小。文中还给出了不同长径比圆柱壳前五阶模态频率的等效杨氏模量系数曲线，利用梁模型并结合此曲线，可准确预报水下圆柱壳低频域辐射声功率和圆柱壳的梁式弯曲振动模态。%In order to improve the computational efficiency of the vibration and the sound radiation of un-derwater cylindrical shells with large length-to-radius ratio in the low-frequency range, a method by using the equivalent beams is proposed. The equivalent beam theoretical model is based on Euler-Bernoulli beam theory, in which the interaction between the structures and water is approximated to added mass. Different equivalent Young’s modulus coefficients for the beam models are obtained, through which the modal fre-quencies of the beams are made identical to the beam-type modal frequencies of the cylindrical shell with large length-to-radius ratio (L/a>20). The results show that the equivalent Young’s modulus coefficients are mainly dominated by the length-to-radius ratio for cylindrical shells, and the effect of the shell thickness on those is much weaker. The equivalent Young’s modulus coefficients curves for the first five order beam-type natural frequencies of cylindrical shells with different length-to-radius ratio are calculated, through which the radiated sound power and the beam-type modes of underwater cylindrical shells in the low-fre-quency range can be precisely predicted by using a simple beam theoretical model.
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