Structural Optimization Design For Leg Mating Unit In Offshore Platform Float-over Installation

The tonnage of offshore platform topside is increasing in domestic,and thousands of tons of offshore platform is becoming very common; the weight of the new offshore platform model has exceeded the floating crane lifting capacity. Traditional methods to install these offshore platform have not met demand for offshore installation yet. However, as a new installation method, float-over has been recognized by the engineering community, and widely used in practical engineering installation. Leg Mating Unit is a key device to the float-over installation process, so it plays a very important role in offshore platform uplift installation. The purpose of this article is to make a structural optimization design to Leg Mating Unit, and provide technical support for the successful installation of offshore platform.Firstly, this article uses analysis software ABAQUS to create the modeling of Leg Mating Unit, considers the contact and friction between different materials, and provides to Leg Mating Unit with vertical and horizontal loads to simulate the force of vertical and horizontal, analyses force-deformation of Leg Mating Unit, obtains the stress and displacement of LMU under the two kinds of load.Secondly, in order to make the force more reasonable to LMU, this article makes the structural optimization design of piston and steel frame in the LMU. This article researches the thickness of piston and steel frame, and the inside pipe contact distance with the pad, rubber, steel. The analysis results show that the final optimization to LMU is not only able to withstand a vertical load of1750tons but also withstand a load of250tons of the perpendicular contact surface to the V-shaped.Lastly, this article discusses impacts of the floors of verticaly rubbers in the LMU. For an example, comparing same vertical height of two-layer with three-layer rubber. It analyses the effects of two kinds of different rubber layers in the LMU by setting up the same height. The results show that the maximum stress of each parts has little change in the LMU under the effect of static loads, but it has big influence on the displacement.