# Optimization Design of Filament Wound Composite Pressure Vessel Based on OpenSees
## 1 Introduction  
Carbon fiber composite material refers to a new type of composite material with high specific strength, high specific stiffness, high-temperature resistance, and good designability, which is formed by using carbon fiber or carbon fiber fabric as reinforcement, resin as a matrix, and certain composite methods [1]. Due to the good mechanical properties and chemical stability of carbon fiber composites, it undertakes the important task of new product development and technological breakthrough in major national strategic fields such as energy, transportation, aerospace, national defense, and military industry. Especially in the field of national defense and military industry, special materials represented by carbon fiber composite materials play an irreplaceable role in the upgrading of weapons and equipment and the research of new models [2]. The structural analysis and optimization design of composite pressure vessels have very important theoretical significance and engineering application value. Fiber winding is a technology for manufacturing composite structures. This technology uses a stationary rotating mandrel, and the guide arm moves horizontally with the mandrel [3]. There is a curved eye on the arm, which is used to group and distribute pre-impregnated fibers, called roving. When the mandrel rotates, the roving is wound on the surface of the mandrel to form a composite winding. The accurate direction of the composite winding is determined by the conveying rate and the rotation speed of the mandrel. The fiber is impregnated in the resin before wrapping the mandrel and then cured with the fiber. After the fiber coating is completed, the entire component, mandrel and composite coating are placed into the oven and heated and cured at the required temperature. When the composite resin [4] is completely cured, the mandrel is removed, leaving the hollow composite structure. The winding angle, fiber thickness, and layering method of the fiber winding layer have a great influence on the overall performance of the composite pressure vessel. Determining howto determine the optimal value of these parameters is a major problem in the design and production of composite pressure vessels [5]. With the continuous advancement of computer and software technology, fine modeling has gradually become an effective method. At present, SAP2000, ANSYS, ABAQUS, OpenSees, etc. have been widely used in the world, and a large number of numerical simulations and parametric studies have been carried out on composite pressure vessels. By comparing the effects of different winding angles on the stress of carbon fiber composite pressure vessels, [PERSON] et al. [6] determined the failure according to the maximum strain criterion, the maximum stress criterion, and the Tsai-Wu failure criterion. It was found that the performance of the pressure vessel when the fiber winding angle was 51\({}^{\circ}\) was significantly better than that of other pressure vessels. [PERSON] et al. [7] used the grid theory and finite element model to design the carbon fiber winding ultra-high pressure pre-mixed abrasive tank, which reduced the mass of the traditional abrasive tank by 80%, and the mechanical performance of the tank was better. [PERSON] [8] aimed at the current situation in which the research and application of high-strength medium modulus T800 carbon fiber are less, and the T800 carbon fiber fully wound composite pressure vessels with different diameters were obtained by the dry winding process, which laid a theoretical and experimental foundation for the industrial application of high performance T800 carbon fiber. In the existing literature, the FEA methods used in the design of filament wound pressure vessels mainly include special analysis and standard analysis. (a) Special analysis methods mainly include special one-dimensional, two-dimensional, and three-dimensional finite elements, the Ritz method, finite differences, and other linear and nonlinear analyses.