Structure Response Analysis Of Non-bonded Flexible Composite Pipe

Non-bonded flexible composite pipe combines the strength of a steel pipe with the flexibility and corrosion-resistant of a polymer pipe,and also the non-bonded layer structure design make it more flexible and adaptive in severe service condition. Therefore, it can be used as the oil and gas transmission component such as air refueling flexible pipe in aerospace engineering. But at the same time, the complicated structure design has also brought great difficulty to the structural response analysis, including the effects of the nonlinear characteristics introduced by contact and friction between layers. Studying the structural response characteristics of the composite pipe and grasping its structural characteristics and mechanical properties,has a great meaning for ensuring the safety of the oil and gas transmission process.Based on this background and the existing theoretical research results, this thesis studies the structural response of a typical non-bonded flexible composite pipe. An analytical model of this pipe is established. We firstly establish the mechanical model and obtain the corresponding stiffness equation of each layer separately, and then the overall stiffness of the whole model is found by summing the stiffness contributions of each layer. For the complex structure layers such as internal carcass layer and pressure armor layer, for computational convenience, are simplified as anisotropic cylindrical shells. Based on this analytical model,the finite element numerical model of non-bonded flexible composite pipe is also established by using ABAQUS, and the interaction between layers and the friction factor are taken into account to capture the nonlinear effects. The proposed analytical model and the finite element model are validated by comparing the results with the existing experimental results. Finally,for the tensile armor layer, a local model of the non-bonded flexible composite pipe is established. This model is composed of an internal cylindrical shell and a single tendon helically wounded on it. By observing the response of the model under external load, the effects of lay angle and friction coefficient to the slip behavior of the tendon are studied. This helps to study the response characteristic of the whole model.The theoretical research of this thesis provides a feasible analysis process and analysis method for the structural response analysis of non-bonded flexible composite pipes in different application fields, and provides guidance for engineering practice.