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This paper analyses the natural frequencies and modes of ‘A’ form derricks. Using the random perturbative finite element methods, the first-order and second-order sensitivities are calculated when several structural parameters of elements are changed randomly. The expressions of the random structural eigenvalues of ‘A’ form derricks are given. The results and conclusions are valuable for designing new oilfield derricks in the future.
This paper analyzes the natural frequencies and modes of ’A’ form derricks. Using the random perturbative finite element methods, the first-order and second-order sensitivities are selected when several structural parameters of elements are changed randomly. The expressions of the random structural eigenvalues of ’A’ form derricks are given. The results and conclusions are valuable for designing new oilfield derricks in the future.