An Improved Fourier Series Method for the Free Vibration Analysis of the Three-Dimensional Coupled Beams

Figure 5

The first eight modes of coupled beams with 90° coupling angle: (a) the first mode, (b) the second mode, (c) the third mode, (d) the fourth mode, (e) the fifth mode, (f) the sixth mode, (g) the seventh mode, and (h) the eighth mode.

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)