An extraction of the natural frequencies and mode shapes of marine risers by the method of differential transformation

In the offshore oil and gas industry, marine risers are critical conductors connecting platforms to the wellheads at the seabed for drilling, production and transmission, the vortex-induced vibration design of which requires accurate knowledge of the natural frequencies and mode shapes. The vibration characteristics of marine risers are re-examined in this paper using the method of differential transformation, which is relatively new technique capable of dealing with eigenvalue problems rather efficiently. Natural frequencies and mode shapes of marine risers are examined for various boundary conditions, and solutions are compared with numerical and experimental results published in the literature where available. (C) 2009 Elsevier Ltd. All rights reserved.