Design Optimization and Non-Linear Buckling Analysis of Spherical Composite Submersible Pressure Hull

• Main Authors: Muhammad Imran, Dongyan Shi, Lili Tong, Hafiz Muhammad Waqas, Riaz Muhammad, Muqeem Uddin, Asghar Khan
• Format: Article
• Language: English
• Published: MDPI AG 2020-05-01
• Series: Materials
• Subjects: optimization; genetic algorithm; composite spherical pressure hull; static structural analysis; buckling analysis; collapse depth
• Online Access: https://www.mdpi.com/1996-1944/13/11/2439

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 (<em>B.F</em>) was selected as the design optimization objective. The Tsai-Wu and Tsai-Hill failure criteria and buckling strength factor (<em>λ</em>) 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 (<em>B.F</em>) over an equivalent spherical steel pressure hull was computed for carbon/epoxy. Moreover, carbon/epoxy displayed larger decreases in buoyancy factor (<em>B.F</em>) 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.