Vibration modes of untwisted (A and C) and pre-twisted (B and D) beams (think plant stems) with width/height b/h =1 (A,B) and b/h = 10 (C,D)

Fig. 4. First five mode shapes of two kinds of beams, where b/h is 1 in (A) and (B), and 10 in (C) and (D). The beam in (A) and (C) is straight, while the beam in (B) and (D) twists 360 degrees uniformly along its length direction.

From the same paper as the previous 2 images.

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