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 was selected as the design optimization objective. The Tsai-Wu and Tsai-Hill failure criteria and buckling strength factor 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 over an equivalent spherical steel pressure hull was computed for carbon/epoxy. Moreover, carbon/epoxy displayed larger decreases in buoyancy factor 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.
Highlights
Due to their beneficial properties: their large specific rigidity, large elastic modulus, enhanced fatigue features, light weight, corrosion resistance, and reduced magnetic and acoustic signatures [1]when compared to metals, Fiber Reinforced Composites (FRCs) are increasingly used in different types of industries
The aim of the present research is to determine the decrease in buoyancy factor (DBF ), compared to a reference steel hull i.e., on a spherical pressure hull through the use of composite materials as a replacement for HY100 steel
The results of lay-up [0S /90T /0U ] listed in Table 5 demonstrates that the minimum buoyancy factor (B.F) of 0.06117 with DBF equal to 65.937% was computed for carbon/epoxy
Summary
When compared to metals, Fiber Reinforced Composites (FRCs) are increasingly used in different types of industries. FRCs have been used in the modeling and fabrication of various shapes pressure hulls including elliptical, cylindrical, spherical and ovoid because of their greater strength-to-weight ratio than metals and other alloys [2]. Many studies are available concerning the optimization of composite pressure hulls featuring cylindrical and elliptical configurations. As reported in the latest research, spherical and ovoid pressure hulls fabricated with steels and other metal alloys were shown to possess better characteristics than other types of pressure hulls. It is very important to conduct optimization studies of the composite spherical pressure hull to further explore the benefits of using composites in its construction
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