Structural Nonlinear Analysis of a Disconnector Pelikelo (a kind of hook) using ANSYS Workbench
The objective of this work is to analyze the structural integrity of a device used to launch torpedo-stakes(structural support to fix platforms in the ocean ground) in the sea. This device named Pelikelo make a connection between the fixed chain and the chain attached to the stake. The use of this device helps PETROBRAS to reduce costs during the installation of the stakes and contribute to reduce the trash in the ground of the ocean, considering that part of the chain is recuperated during this operation. Pelikelo is a new piece developed and patented by MCS to be used inside the ocean to launch the stake. The first operational test of this piece was verified by Classification Societies. This device is a kind of hook composed of three parts. The intermediate piece named Pelikelo open during the operation to release the chain connected to the stake which will be fixed in the ocean ground to support offshore platforms. The solid model was elaborated in a CAD program as an assembly composed of 10 parts, including 5 bolts, 2 shackles and the 3 main parts including the Pelikelo. The finite element model is composed of high order solid elements. The mesh was elaborated using the hexadominant meshing technique. The contacts between parts are surface-to-surface with friction. A nonlinear static stress analysis, in ANSYS/Workbench, is executed using a nonlinear isotropic hardening material model. The load is multiplied by a dynamic factor according to the technical codes. Several analyses were executed to adjust mesh, parameters, algorithms, types of contacts elements and to choose the best solver for this analysis. Several analyses were executed with different distribution of loads. Plastic strains appeared in some regions, mainly in the internal surface of the Pelikelo. Based in these results the geometry of Pelikelo will be modified to avoid plasticity and to respect the safe factor requested by the technical codes and Classification Societies. Although the virtual prototype and the analysis executed in ANSYS are simple, the simulation analysis was very important in this project. It was required by the client due to the difficulties when trying to simulate the operational conditions of working in the ocean in laboratory tests.