A study on whipping related double bottom response as well as its statistical characteristics based on full-scale measur
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ORIGINAL ARTICLE
A study on whipping related double bottom response as well as its statistical characteristics based on full‑scale measurements Jie Chen1 · Tetsuo Okada2 · Yasumi Kawamura2 · Xi Chen2 · Taiga Mitsuyuki2 Received: 2 May 2020 / Accepted: 28 September 2020 © The Japan Society of Naval Architects and Ocean Engineers (JASNAOE) 2020
Abstract Recently, the great enlargement of container ships has brought broad concern on the effect of whipping response. Meanwhile, the accompanying wider width of double bottom may cause more flexible responses of the double bottom structures. The numerical simulation studies have shown that the longitudinal stresses of the hold central bottom of a container ship due to the double bottom bending superimpose on the longitudinal stresses due to hull girder bending in both wave response component and vibrational response component. In this research, the authors firstly extract the full scale measurements data whose sea states are closest to that of numerical simulation among existing time series, with the purpose of analyzing correlation between double bottom bending and hull girder bending in wave response and vibrational response. As a result, studies from full scale measurements well verified the phenomenon that double bottom of larger container ship responds to forced vibration due to whipping excitation as observed in theoretical studies. Then, the statistical characteristics of correlation factor between hull girder bending stress and double bottom bending stress were investigated, based on relatively large number of data with regard to wave height and relative wave direction, as well as the classification between low- and high-frequencydominant response cases. All these studies may contribute to future optimized operation, maintenance and design of ship. Keywords Full-scale measurements · Whipping · Double bottom response · Statistical characteristics · Large container ship
1 Introduction The rule based methods used for the estimation of waveinduced loading in ship design has been proven to be adequate enough by relying on empirical rules supported by actual operation experience. However, due to the sharp increase in the size of ocean vessels, such as ultra-large * Jie Chen chen‑jie‑[email protected] Tetsuo Okada okada‑[email protected] Yasumi Kawamura kawamura‑yasumi‑[email protected] Xi Chen chin‑xi‑[email protected] Taiga Mitsuyuki mitsuyuki‑taiga‑[email protected] 1
Graduate School of Engineering Science, Yokohama National University, Yokohama, Kanagawa 240‑8501, Japan
Faculty of Engineering, Yokohama National University, Yokohama, Kanagawa 240‑8501, Japan
2
container ships, hydro-elasticity has become an innegligible consideration. It refers to vertical resonant hull girder vibration due to oscillating wave loads along the hull of the ship, called springing and transient vibrational response due to excessive impulsive loading in the bow or stern of the vessel, called whipping. Particularly, whipping plays a significant role in evaluating hull girder ultimate strength and safety
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