Fig. 1. Schematic diagram of fuel rod clamping

Fig. 2. Grid-constraint simplification process

Fig. 3. Diagram of multi-span continuous beam model with elastic constraints

Fig. 4. Discontinuity of displacement functions at endpoints based on traditional Fourier series expansion and its solution

Fig. 5. The relationship curves between the first six natural frequencies and series solution truncation numbers of a fuel rod under elastic support

Fig. 6. Variation of 1st order natural frequency of fuel rod with spring stiffness

Fig. 7. The first six vibration modes of a fuel rod vibration modes of fuel rods under elastic boundary conditions (a) and simply supported boundary conditions (b)

Fig. 8. Intrinsic frequency distribution of fuel rods with different span numbers (color online)