Construction of the Mega-Frame Platforms Based on Topological Optimization

The mega-frame platform (MFP) is a new type of antivibration platform using the mega-frame theory. Its construction, or layout, doesn’t have the international, national or industry de facto standards to be referred to. In order to increase the MFP’s performance and decrease its steel consumption, the topological optimization whose purpose is to find out the best use of material is used in the construction of the mega-frame platform. Firstly, the MFP is built with uniform thickness slab. Four pieces of the slabs constitute a huge frustum of rectangular pyramid which is the same function with the jacket for the common jacket platform. When the MFP’s global stiffness which is the objective criterion taking an extreme value subject to the volume reduction under the given loads, the mega-frame platform has the best topological shape. Some material of the huge frustum of rectangular pyramid is removed. And the prismoid’s walls become netlike structures. Secondly, equivalent stiffness dimensional trellis trusses are chosen as the substitute for the reserved material that constituted the netlike structure. Thirdly, the new platform is mode analyzed. The analyses show that the platform has no mode shape distortion and the best static and dynamic performance. Lastly, vibration control simulations of megaplatforms subject to random excitation wave loads are done using FEM software. Results show that the new MFP has better vibration control effect than the traditional jacket platform under the same out loads.