多跨连续梁自由振动分析的边界元法

核动力装置中的燃料元件棒和换热器传热管,常按多跨连续梁模型进行动力分析。本文用直接边界元法来分析这类多跨连续梁的特征值问题,推导出有轴向力作用和弹性支承条件的求解公式,并对压水堆燃料元件棒的固有频率和振型作了计算,得到较为满意的结果,可以看出,边界元法便于处理杆系结构问题,即使杆系的复杂度增加,而解题基本方法的复杂度并不增加。

Analysis of Free Vibration of Multi-Spanned Continuous Beams by the Boundary Element Method

Dynamic analysis model of the nuclear fuel element and the tube of heat exchangers in nuclear power installation is treated as a multi-spanned continu-ous beam.In this paper,the direct boundary element method(BEM)is used for analyzing the eigenvalue problems of the multi-spanned beams.The solu-tions of equations of multi-spanned beam with various kinds of support and with a constant axial force have been obtained.And the method was applied to the numerical calculation of natural frequencies and mode shape of a nuclear fuel element in PWR.The results are satisfactory.It is shown that BEM is easy to treat the dynamic analysis problems of a beam system,and it is more ac-curate and easier than finite element method(FEM).