Investigation of parametric behaviour of reinforced thermoplastic pipes under dynamic loading

Glass-fibre reinforced pipes (GFRP) are increasingly being used in the oil and gas industry for their chemical resistance, corrosion resistance, flexibility in design, high strength-to-weight ratio, and high stiffness-to-weight ratio. They are slowly replacing steel pipes, both onshore and offshore, to transport oil and gas over large distances. Such pipes can be susceptible to accidental dynamic loads from low velocity impacts with high magnitudes of force. To ensure these pipes can safely operate after being subjected to such impact loading conditions, it is vital to investigate their resilience to impact. The nature of these impacts can potentially lead to catastrophic damage, resulting in huge losses. In this work, a numerical study has been conducted in LS-Dyna to investigate the behaviour of glass-fibre reinforced pipes under different impact loading conditions. Two parameters for the reinforcement layer were examined to understand their effect on the overall behaviour of the pipe under dynamic impact to achieve a multi-optimisation strategy capable of enhancing the impact absorption capacity. Different angle (+45/-45, +15/-85, +60/-30, +60/-60, +75/-25, +85/-15) and thickness (combos) combinations were implemented for the GFRP to observe the optimal combination for maximum dynamic impact absorption with a deformable boundary constraint. The existing design of the GFRP was numerically analysed and validated based on ASTM D2444-21 to establish the viability of the simulation as well as its utilisation for further investigation. An iterative method of thickness and angle combinations was implemented through simulations and a composite pipe based on the optimal combination was manufactured as well as experimentally validated. The comparison between the existing design of the GFRP simulation and experimental results show a difference of 7% whereas the optimised pipe results (thickness of 2.5-2.5 mm and angle of +60/-60) show a difference of 15%. The increase in the difference percentage can be attributed to the introduction of modified reinforcement on the proposed composite, constructed with aluminium infused nanocomposites in the resin. The impact resilience of the newly designed pipes is 11% higher than that of the existing pipe design. This work provides a comprehensive numerical study on different design parameters that can be manipulated to enhance the impact resilience of the GFRP