ADAPTIVE TIME INTEGRATION OF NONLINEAR STRUCTURAL DYNAMIC PROBLEMS

This work presents the development of an adaptive computational strate gy for the efficient nonlinear dynamic analysis of large-scale structu ral systems, particularly oriented towards the analysis of compliant s tructures for deepwater oil exploration and production. This strategy is devised having in mind the following requirements: (a) Superior com putational efficiency when compared with conventional nonlinear dynami c analysis tools; (b) User-friendliness, reflected in savings in the t ime spent by the engineer for the preparation and submission of the co mputer jobs necessary to obtain the dynamic response; and (c) Improved characteristics of reliability and robustness, reflected by the quali ty of the results and the ability to complete an analysis without abno rmal terminations. In order to fulfill these requirements, the adaptiv e algorithm performs automatic time step adjustment, allowing the step value to vary during the analysis according to the modal composition of the dynamic response and to the nonlinear behavior of the structura l system; it also performs the automatic determination of stiffness re evaluations, to minimize the costs related to the calculation of eleme nt matrices, and assembling and decomposition of global matrices. Appl ications on the nonlinear dynamic analysis of deepwater compliant stru tures are presented, to evaluate the aforementioned characteristics of the computational system.