Projekt leder: Jelena Vidic-Perunovic
Samarbejdspartnere: Det Norske Veritas, UC Berkeley
Støttet af Forsknings- og Innovationsstyrelsen, FTP
Springing is a high frequency resonant vibration of the ship hull induced by waves. According to recent references, springing can dramatically reduce fatigue life of a ship and can be the cause for catastrophic structural failures.
Hull's natural vibration frequency decreases with increasing ship size and use of high tensile steel in shipbuilding. Thus, springing is more easily excited by waves. Springing relates to containerships (low hull stiffness, increasing length), tankers (large length, low draft in ballast), fast passenger ships (large speed).
Paradoxically, springing still doesn't get much attention of the technical society. The flexible vibration of the hull is totally disregarded by the current ship design rules. The negligence of springing in design, classification and operation of ships is present because of insufficient knowledge about this complex phenomenon.
It has been theoretically proven that non-linear wave excitation and especially opposing waves interaction represent a very important source of excitation. Other forces in the excitation mechanism must be also included in order to predict springing accurately. E.g. the incident wave will be reflected from the bow and the wave amplitude amplified in front of the ship. This may be especially important for large ships with blunt stem (i.e. tankers, bulkcarriers).
Therefore, the purpose of this project is to advance the knowledge about springing and to communicate it in an applicable form to industry.