TY - GEN
T1 - An experimental study of snap loads on a vertical hanging cable system
AU - Hsu, Wei Ting
AU - Chuang, Tzu Ching
AU - Hsu, Wen Yang
AU - Sharman, Krish
AU - Yang, Ray Yeng
PY - 2019/1/1
Y1 - 2019/1/1
N2 - Sudden snap events on mooring lines and hanging cables can cause spikes in tension, resulting in reduced safety factors during extreme events. For example, the mooring system of a floating offshore wind turbine (FOWT) can be exposed to wave-induced motions making the former vulnerable to snap type impact. Suitable criteria to define snap events are still largely unclear, making current design practices overly conservative. To understand the underlying physics of snap loads on a mooring line system, this paper presents a theoretical development and an experimental parametric study of snap events. The effects of the nonlinearity of bilinear line stiffness and hydrodynamic drag force, as well as the weight of payload on snap events are investigated using the vertical hanging cable model. This cable model includes two springs in series and a payload. The bilinear spring model is designed to create nonlinear dynamic tension. A total of 108 tests were conducted in the wave tank of Tainan Hydraulic Laboratory. The excitation amplitude ranges from 0.01 to 0.04m; excitation time period ranges from 0.5 to 2s; the weight of payload ranges from 6.13 to 18.95N. The tests carried out in water are compared to those conducted in air. It is seen that the hydrodynamic drag force together with the small pretension could result in larger normalized tension ranges.
AB - Sudden snap events on mooring lines and hanging cables can cause spikes in tension, resulting in reduced safety factors during extreme events. For example, the mooring system of a floating offshore wind turbine (FOWT) can be exposed to wave-induced motions making the former vulnerable to snap type impact. Suitable criteria to define snap events are still largely unclear, making current design practices overly conservative. To understand the underlying physics of snap loads on a mooring line system, this paper presents a theoretical development and an experimental parametric study of snap events. The effects of the nonlinearity of bilinear line stiffness and hydrodynamic drag force, as well as the weight of payload on snap events are investigated using the vertical hanging cable model. This cable model includes two springs in series and a payload. The bilinear spring model is designed to create nonlinear dynamic tension. A total of 108 tests were conducted in the wave tank of Tainan Hydraulic Laboratory. The excitation amplitude ranges from 0.01 to 0.04m; excitation time period ranges from 0.5 to 2s; the weight of payload ranges from 6.13 to 18.95N. The tests carried out in water are compared to those conducted in air. It is seen that the hydrodynamic drag force together with the small pretension could result in larger normalized tension ranges.
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U2 - 10.1115/OMAE2019-96424
DO - 10.1115/OMAE2019-96424
M3 - Conference contribution
AN - SCOPUS:85075842789
T3 - Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE
BT - Rodney Eatock Taylor Honoring Symposium on Marine and Offshore Hydrodynamics; Takeshi Kinoshita Honoring Symposium on Offshore Technology
PB - American Society of Mechanical Engineers (ASME)
T2 - ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering, OMAE 2019
Y2 - 9 June 2019 through 14 June 2019
ER -