Design Optimization and Non-Linear Buckling Analysis of Spherical Composite Submersible Pressure Hull
Muhammad Imran, Dongyan Shi, Lili Tong, Hafiz Muhammad Waqas, Riaz Muhammad, Muqeem Uddin, Asghar Khan
Abstract
This paper describes an optimization study of a spherical composite submersible pressure hull employing a genetic algorithm (GA) in ANSYS. A total of five lay-up arrangements were optimized for three unidirectional composites carbon/epoxy, glass/epoxy, and boron/epoxy. The minimization of the buoyancy factor ( B . F ) was selected as the design optimization objective. The Tsai-Wu and Tsai-Hill failure criteria and buckling strength factor ( λ ) were used as the material failure and instability constraints. To determine the effect of geometric non-linearity and imperfections on the optimized design, a non-linear buckling analysis was also carried out for one selected optimized design in ABAQUS. The non-linear buckling analysis was carried out using the modified RIKS procedure, in which the imperfection size changed from 1 to 10 mm. A maximum decrease of 65.937% in buoyancy factor ( B . F ) over an equivalent spherical steel pressure hull was computed for carbon/epoxy. Moreover, carbon/epoxy displayed larger decreases in buoyancy factor ( B . F ) in the case of 4 out of a total of 5 lay-up arrangements. The collapse depth decreased from 517.95 m to 412.596 m for a 5 mm lowest mode imperfection. Similarly, the collapse depth decreased from 522.39 m to 315.6018 for a 5 mm worst mode imperfection.