A TOPOLOGY OPTIMIZATION METHOD APPLIED TO SUBSEA STRUCTURES UNDER SIMULTANEOUS THERMAL EXPANSION AND HYDROSTATIC PRESSURE LOADS

Resumo

The effect of severe environmental conditions, i.e., high pressure and high temperature
(HPHT), is known to cause various difficulties for the design of deepwater structures for oil and gas

production [1]. Subsea structures can be difficult to be repaired and/or replaced in response to the oc-
currence of unexpected problems due to severe HPHT conditions. Therefore, several methods have been

developed to design structures to withstand simultaneous pressure and thermal expansion [2]. This paper
aims to propose a topology optimization method to handle the challenges that simultaneous hydrostatic
pressure and thermal expansion impose on structural design. Topology optimization methods aim to find

optimal material distribution layouts (topologies) on specified design domains minimizing or maximiz-
ing an objective function subject to a set of constraints. The structural topologies are usually organic and

non-intuitive designs and they represent a powerful computational tool in the early stage of the struc-
tural design. Herein, the proposed Topology Optimization of Binary Structures (TOBS) method [3] uses

discrete 0,1 design variables within a finite element mesh to indicate the existence of solid 1 and void 0
material inside the design domain. A fluid pressure field is solved with a separate domain and constant
thermal expansion is applied on the structural volume. Sequential integer linear programming is used

to solve the optimization problem iteratively. The discrete nature of the method presents attractive fea-
tures when dealing with design dependent body and surface loads. In this paper, we use the structural

mean compliance and volume as functions for optimization. The methods of topology optimization have
achieved industrial maturity to be applied in stiffness maximization problems, but they are still quite
limited when it comes to Multiphysics design. A numerical example of a subsea structural design is
explored in this paper.