# Optimization Design of Filament Wound Composite Pressure Vessel Based on OpenSees
## 2 Finite Element Analysis  
The development of composite pressure vessel design is still quite primitive. Usually, only limited analysis is performed to obtain the initial design, and then the design is improved by several \"build and explode\" iterations. However, the material and resource costs of manufacturing multiple test pieces are extremely high. To reduce costs, finite element analysis (FEA) is often used to reduce the number of iterations required. If performed manually, this process may be very cumbersome and time-consuming. Therefore, the finite element analysis process is used to avoid multiple iterations [14]. The standard process of finite element analysis includes defining the model and its load and solving and interpreting the results. If the solution results show that it is necessary to modify the design, then the geometric structure or load of the model must be changed and the above steps must be repeated. Especially when the model is more complex or modified, this process may be expensive and time-consuming. APDL provides users with the function of automatically completing the above cycle using establishing intelligent analysis. In other words, the input of the program can be set to be determined according to the specified functions, variables, and selected analysis criteria [15]. It allows complex data input, giving users control over any design or analysis property, such as geometry, material, boundary conditions, and mesh density, extending capabilities beyond traditional finite element analysis, and extending more advanced operations, including sensitivity studies, parametric modeling of parts, design modifications, and design optimization [16]. Parametric modeling is an important technical means to solve engineering problems by using numerical calculation software. The special structural characteristics of wound pressure vessels complicate the process of parametric modeling [17]. [PERSON] [18] determined the winding tension value through the lining stability analysis, and gave the design of the winding layer by the grid theory. Combined with the linear design and simulation, the winding process of two yarns, five tangent points, and geodesics was determined. Based on this parameter, the accurate modeling of the winding pressure vessel was realized, and the strength analysis of the structure was completed by the finite element software ABAQUS. Using the designed winding parameters, through the four-axis CNC filament winding machine, using T800 carbon fiber and EW-6F epoxy resin, the winding process of two-strand yarn, five-tangent point, and geodesic line was used to complete the molding of a plastic liner carbon fiber fully wound type IV composite pressure vessel. During the winding process, the fibers are evenly and stably distributed on the surface of the inner liner. The number of complete cycles required for the spiral layer to be wrapped is consistent with the line shape simulation results, which confirms the accuracy of the design parameters. [PERSON] [19] determined the angle of the fiber winding layer of the pressure vessel according to the winding forming theory. The spiral winding angle is 19.38\({}^{\circ}\), the circumferential winding angle is 89.14\({}^{\circ}\), the thickness of the winding layer is 0.375 mm, the winding layer is three layers, and the fiber layer is six layers. By establishing the finite element model of the container on the basis of CADWIND, the line type, number of layers, angle, and thickness of the winding layer are designed and analyzed as the finite element model data, and compared with the subsequent experiments. In the hydraulic blasting experiment, after 8 h of curing, the finished product is glued and unglued at the head. The two groups of comparative experiments show that the sealing performance of the glue group is good, which is consistent with the finite element simulation results, and the error is 1.2%.