The current study focuses on the application of the nonlinear negative stiffness mechanism to a Salter's duck, which is a well-known wave energy conversion (WEC) device known for its efficiency of 90% in 2D regular waves. Despite the proven efficiency of WEC devices, they face the challenge of producing a stable system that can effectively extract energy from constantly changing wave conditions. Recent studies have shown that the use of negative stiffness can address this issue, and this approach has been adopted in the present study for the pitch-type WEC-rotor (Salter's duck). The study employed a time domain analysis based on linear potential theory to examine the impact of factors such as spring length and stiffness on wave energy extraction in both regular and irregular wave conditions. The results of the study showed that the incorporation of negative stiffness improves the extraction of wave energy.


Ocean energy is one among the option that has received a lot of attention. The emphasis on ocean energy is due to its ability to provide a reliable source of energy while causing no environmental harm. Ocean energy is likely to play an important role in meeting the growing demand for clean energy (Mei, 1976; McCormick, 2013; Cruz 2007; Pecher and Kofoed, 2017). Wave energy converters, or devices that capture energy from ocean waves, have been extensively researched and developed in recent years (Clément et al., 2002; Falnes, 2007; Drew, 2009; Pecher and Kofoed, 2017). The first wave energy device that was successfully deployed in large numbers in Japan was implemented by Yoshio Masuda in the sea. This achievement was followed by the Japan Marine Science and Technology Centre's development of large-scale wave energy converters in the late 1970s and 1980s. (Setoguchi and Takao, 2006). Despite the fact that there are numerous designs and concepts available in the literature, the challenge has been to translate these concepts into commercially viable products. Converting wave energy into usable electricity is a complex process, and achieving the necessary levels of efficiency and cost-effectiveness to make these devices commercially viable can be difficult (Clément et al., 2002). Despite these obstacles, progress has been made, and some wave energy converters are now commercially available. However, more research is needed to fully realize wave energy's potential as a reliable source of clean energy (Sheng, 2019).

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