Implementation of Smart-Elastomer Tensioner in TLP-TAD Hawser Connection System to Mitigate Hawser Snapping Tension

A smart tensioning system with a controllable elastomer was implemented in TLP-TAD hawser lines to mitigate an excessive increase in hawser tension. The applied elastomer material can be softened by applying an electrical current. Simulations with traditional hawsers showed that snap loadings existed, and they were caused by out-of-sync motions between TLP and TAD. Frequency-domain two-body hydrodynamic analysis was first carried out to obtain hydrodynamic data. Then, fully coupled time-domain simulations were carried out using the in-house program CHARM3D. A rigidity-tuning conductive elastomer (RCE) tensioner was sized considering available data and manufacturability. A control scheme that imitates an ABS (anti-lock braking system) using repeated grab and release was developed. The control scheme repeatedly alternates high and low elastomer stiffnesses with variable electric currents to keep the hawser-snap loading below the target. The control scheme was incorporated into time-domain simulations. The base case with fairlead hawser connections showed a strong correlation in hawser tension and TLP-TAD relative surge. The implementation of the RCE tensioner almost halved the hawser maximum tension while maintaining the allowable maximum tensioner stroke. The present research shows that the use of a smart material with proper control can significantly lower maximum hawser tensions between adjacent floating platforms. Two major innovations include the use of a smart elastomer and an ABS-like control method to reduce the maximum tension of the hawser/cable.