Buckling Analysis Of Plastic Pipe Reinforced By Winding Steel Wires Under External Pressure

Plastic pipe reinforced by winding steel wires (PSP) is a new type of thermoplastic matrix steel composite pipe, which combines thermoplastic polythene (HDPE) on the inside and outside of the pipe wall with steel wire mesh skeleton sandwiched in the middle. The mesh skeleton is formed by crossly winding high strength steel wire and tightly integrated with HDPE by high performance cohesive resin. Owing to the unique structure, PSP integrates the advantages of high intensity, corrosion resistance and low production cost. With the excellent performance, there is a good foreground of using PSP in petroleum, chemistry engineer, construction project, pharmacy and so on.PSP deforms under external pressure, such as buried, subsea or vacuum condition, and is destroyed by buckling when loading is over critical pressure. Then it is necessary to research buckling of PSP after strength analysis completed. Supported by Wenzhou science and technology project, titled 'structure mechanical model research and optimization design for composite pipe reinforced by winding steel wires' (G2004034) , this paper researched on buckling of PSP under external pressure systematically in theory, FEA and experimentation. The main works were as follows:Firstly, calculation method of buckling critical pressure was established. PSP was simplified as orthotropic laminated cylinder shell, and elastic parameters of monolayer were estimated based on rectangle model. Short-term buckling critical pressure was deduced from composite shell theory. Influence factors of critical pressure were analyzed to get design method of PSP structure stability. Creep buckling was discussed and estimated method of long-term pressure was given at the same time. Theory calculation results show good agreement with experimental data and the calculation method can be sed for predicting short-term buckling critical pressure well.Secondly, shell model was built in FEA software, and short-term bucklingcritical pressure was calculated in eigenvalue buckling analysis and nonlinear buckling analysis, with boundary conditions and initial defect considered. Nonlinear buckling analysis result is closer to experimental data than eigenvalue buckling analysis result and predicts short-term buckling critical pressure well.Finally, measuring devices of external hydraulic pressure and vacuum were designed for short-term buckling and creep buckling character. Using these devices, short-term buckling critical pressure, pressure loading-deformation relation curves, creep deformation with time and creep buckling critical time in different pressure relation curves can be got.