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A previous study by the authors proposed a new type of damper, the pounding tuned mass damper (PTMD), which uses the impact of a tuned mass with viscoelastic materials to effectively dissipate vibration energy, for structural vibration control. However, the control performance is unknown if the PTMD is not tuned to the targeted frequency of the primary structure. This paper aims to study the robustness of the PTMD against the detuning effect both numerically and experimentally. The control object was chosen as a subsea jumper, which is a flexible M-shaped pipeline structure commonly used in offshore oil and gas production. In this paper, a 15.2 m (50 feet) long jumper incorporated with a PTMD was set up. To enable the numerical study, the equation of motion of the jumper along with the PTMD was derived. Three testing cases were numerically studied: free vibration, forced vibration and forced vibration with varied frequencies. In all cases, the PTMD can effectively suppress the structural vibration when the natural frequency was off-tuned. Furthermore, experimental studies were conducted. The experimental results also implied the robustness of the proposed PTMD.

One of the largest movers of the world economy is the oil and gas industry. The industry generates billions of barrels of oil to match more than half the world’s energy demands. Production of energy products at such a massive scale is supported by the equally massive oil and gas infrastructure sprawling around the globe. Especially characteristic of the industry are vast networks of pipelines that traverse tens of thousands of miles of land and sea to carry oil and gas from the deepest parts of the earth to faraway destinations. With such lengths come increased chances for damage, which can have disastrous consequences owing to the hazardous substances typically carried by pipelines. Subsea pipelines in particular face increased risk due to the typically harsher environments, the difficulty of accessing deepwater pipelines, and the possibility of sea currents spreading leaked oil across a wide area. The opportunity for research and engineering to overcome the challenge of subsea inspection and monitoring is tremendous and the progress in this area is continuously generating exciting new developments that may have far reaching benefits far outside of subsea pipeline inspection and monitoring. Thus, this review covers the most often used subsea inspection and monitoring technologies as well as their most recent developments and future trends.

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Pounding tuned mass damper (PTMD) is a novel type of passive damper. The PTMD utilizes collisions or impacts of a tuned mass with viscoelastic materials to efficiently dissipate the vibration energy of primary structures. The previous studies have verified its effective damping performance on a full-scale subsea jumper and other structures in air. This paper presents the first-ever experimental verification of a submerged PTMD system for vibration control of pipelike structures underwater. To facilitate the experimental studies, a vertical vibration system consisting of 4 springs and a cylindrical steel pipe was designed and set up in a water tank. Furthermore, a numerical method considering the effect of the added mass is described to estimate the natural frequencies of a submerged cylindrical pipe. Therefore, experimental results demonstrate that the PTMD system is effective and efficient to suppress the forced vibrations of the submerged cylindrical pipe at the tuned frequency and is also robust over a range of detuning frequencies.