Transfer functions for thermoplastic composite pipes subjected toaxisymmetric mechanical and thermal loading

Abstract

Thermoplastic composite pipes (TCPs) offer an ideal alternative to traditional nonbonded flexible and steel risers for deepwater applications, as their high specific strength, stiffness, and corrosion resistance provide significant advantages. In this paper, linear transfer functions are developed to present the response of TCPs exposed to axisymmetric loads (tension, internal and external pressures, and torque) and thermal loading. This approach allows, for any load combination, quick evaluation of strains, stresses and assumed failure criteria. Considering heat convection conditions, the stationary temperature distribution within the pipe is determined by solving the heat conduction equation along the wall. Moreover, the temperature-dependent material properties are considered in the thermo-mechanical analysis. A case study is performed to illustrate the application of the methodology proposed in this work, and the stress transfer functions caused by unitary mechanical loads and thermal load are presented. These functions enable rapid calculations while providing results equivalent to those of the complete thermo-mechanical analysis. Besides, the maximum load envelopes are evaluated based on Hashin and von Mises failure criteria which are respectively employed for the laminate and homogeneous layers. The validation of the proposed model is also demonstrated in the end.