Finite Element Analysis And Optimization Design Of Carbon Filament Fully-Wrapped Composite Cylinder With Aluminum Alloy Liner

The composite cylinder with the characteristics of light weight, corrosion resistance, airproof property, high reliability and so on has been widely used in military use and civilian applications. With the wide application of composite cylinders, it is very important to scientifically research and accurately analyze the cylinders. With the development of computer technology and the maturity of finite element method, numerical calculation method has become an important method of researching on composite cylinders. The finite element analysis and optimization design of fully-wrapped composite cylinder with aluminum liner are carried out by software ANSYS. The main researches on the fully-wrapped composite cylinder are as follows:(1) Mechanics analysis of liner and filament winding layers. This paper simplified the cylinder model and derives the stress and strain formula of liner. Based on the net theory, gives the fiber thickness and fiber stress formulas of cylinder body; derives the filament winding angle, filament thickness and filament stress formulas of equilibrium equal stress head.(2) Finite element analysis of fully-wrapped composite cylinder. Parametric finite element model, which had maximum consistency with the mechanical characteristic of the fully-wrapped composite cylinder, was established by parametric programming language (APDL). In the model,the totals of filament wound layers were handled as composite laminate, In addition the influence of winding tension was considered. The model achieves thickening and variable Angle of spiral fiber layers on head. Compare the result of the experiment and the predictive value of burst pressure to assure the model is accurate. This paper analyses finite element calculation on composite cylinder under the six operating conditions (filament wound residual prestress,auto-frettage pressure,zero pressure,working pressure,hydrostatic testing pressure,minimum burst pressure). The result shows that this cylinder accords with the provisions of DOT-CFFC.(3) Optimization design. According to the provisions of DOT-CFFC and the requirements of stress under operating conditions, mathematical model was established and the objective function was maximum stress of liner under working pressure. This paper optimizes the auto-frettage pressure and filament wound residual prestress of fully-wrapped composite cylinder using the design optimization method provided by ANSYS, and gets the optimal value of the two parameters, which makes the stress of liner under working pressure lower and improves the reliability of the cylinder. This optimization method is effective to shorten product design cycles and costs. The influence of the two optimization variables on cylinder is studied. The results provide certain reference value for design and production.(4) The research about auto-frettage pressure and filament wound residual prestress. According to the above finite element model, the necessity of auto-frettage on composite cylinder was researched. The result shows that the auto-frettage operation can reduce the stress level of liner and improve the load distribution between the fiber layers under working pressure. As a result, the high strength characteristic of composite material can be fully exhibited. The filament wound residual prestress was researched. The result shows that the larger filament wound residual prestress can reduce the stress level of liner at working pressure, but the influence on the stress level of filament is less.