Failure analysis of thermoplastic composite pipe (TCP) under combined pressure, tension and thermal gradient for an offshore riser application

Abstract

Useful characteristics of fibre-reinforced thermoplastics, including high specific strengths and moduli and excellent corrosion resistance, make them ideal candidates for offshore riser pipe applications. When in operation, risers are subjected to combined mechanical and thermal loading. In the present paper, a 3D finite element (FE) model is used to analyse stress state in a section of thermoplastic composite pipe (TCP), consisting of a fibre-reinforced thermoplastic laminate fully bonded between inner and outer thermoplastic liners, under conditions illustrative of a deepwater riser application. The effects of varying combinations of pressure and thermal differentials on the distribution of stress-based failure coefficient are examined. Failure responses under different axial tensions at low/high pressures and temperatures are assessed for configurations with different laminate ply stacking sequences. Temperature-dependent material properties are considered in the thermomechanical analysis.

Numerical modelling of spoolable thermoplastic composite pipe (TCP) under combined bending and thermal load

“…Thus, both spooling and operating stages must be carefully considered in conjunction during the design phase. For the same dimensions, the [(±55) 2 / (±30) 2 ] arrangement was previously shown to be effective when operating under combined pressures, thermal gradient and high tension illustrative of a deepwater riser application (Hastie et al 2019b). Based on results of the current paper, tailoring the laminate for deepwater operation by orientating a portion of layers at a low angle would have a detrimental effect on spooling capacity due to high utilisation of fibre compressive strength.…”

“…Properties at 23°C are assumed. We consider the dimensions in (Hastie et al 2019b). Under bending, the top (θ = 0 as per Figure 1 coordinates) and bottom (θ = π) of the pipe are under axial tension and compression, respectively.…”

“…Predicted burst pressure decreased by 2-3% based on coefficients obtained from 30-day submersions of specimens at 80°C. Hastie et al (2019aHastie et al ( , 2019bHastie et al ( , 2020 performed 3D FEA to investigate the influence of thermal gradient on the failure of carbon/PEEK TCP under combined pressures and tensions illustrative of deepwater riser operation. The effects of increasing operating temperature are less pronounced under high pressure where the laminate experiences greater utilisation.…”

Mechanical behavior of metallic strip flexible pipes during reeling operation

“…To investigate how composite flexible pipes fail exactly, scholars have made a lot of effort from a local point of view [25][26][27][28]. Xu et al [29] investigated the mechanical behavior of fiberglass reinforced bonded flexible pipe subjected to tension by experimental, theoretical and finite element method, proving that HDPE is the main component provides tension resistance during the loading process.…”

Coupled thermomechanical analysis of thermoplastic composite pipe by FEM simulations

“…Thermoplastic composite pipe (TCP), consisting of fibre-reinforced thermoplastic laminate with inner and outer thermoplastic liners, is a lightweight spoolable pipe solution on the cusp of deployment in deepwater riser applications. During operation the pipe is subjected to pressure and tension in combination with large through-wall thermal gradient arising from the mismatch between temperatures of the pipe contents and surrounding ocean [1]. In this work, a 3D finite element (FE) model is developed to analyse stress-based failure of TCP subjected to load combinations representative of deepwater operation.…”