This paper presented the results of an experimental investigation into the resistance performance of a wave-piercing trimaran with three alternative side hull forms, including asymmetric inboard, asymmetric outboard, and symmetric at various stagger/ separation positions. Model tests were carried out at the National Iranian Marine Laboratory (NIMALA) towing tank using a scale model of a trimaran at the Froude numbers from 0.225 to 0.60. Results showed that by moving the side hulls to the forward of the main hull transom, the total resistance coefficient of trimaran decreased. Findings, furthermore, demonstrated that the symmetry shape of the side hull had the best performance on total resistance among three side hull forms. Results of this study are useful for selecting the side hull configuration from the resistance viewpoint.
Bottom slamming loads cause considerable local damage to a ship’s body and reduce the ship’s structural performance against harsh sea waves. Although extensive studies have worked on stiffening elements to compensate for local damage due to slamming loads, few studies have concentrated on the ship’s body itself while using new generations of composite plates. Accordingly, a numerical study is conducted to determine the effect of using ultra-lightweight high-ductility cementitious composite in steel–concrete–steel (SCS) composite plate to mitigate bottom slamming loads. A large-scale model of the ship using SCS composite plates is modelled in Abaqus software, and fluid–solid (FSI) interaction is precisely modelled using the Coupled Eulerian–Lagrangian (CEL) method. The results show that using the CEL method with a large-scale 3D model precisely simulates FSI by providing a 6.5% deviation from the experimental result. Moreover, using an SCS plate when considering ultra-lightweight high-ductility cementitious composite results in a considerable reduction (around 95%) in the maximum strain of the ship body and, accordingly, reduces local damage so that, although about 22% of the strain of the outer layer is transferred to the inner part of the ship body containing only steel plate, almost 0% stress transfer is observed for the SCS-based ship’s structure.
The outrigger symmetry of a trimaran is believed to significantly affect its hydrodynamic functioning. The present study was conducted to investigate the added resistance responses and experimental vertical motion of a wave-piercing trimaran in regular head waves. A series of experiments have been carried out in the National Iranian Marine Laboratory (NIMALA) towing tank to determine the effect of side hulls symmetry on the heave and pitch motions and added resistance. The models were tested over a range of wave frequencies and Froude numbers using both symmetric and asymmetric outriggers. According to the results, the symmetric side hull form based on heave motion, the outboard form in terms of pitch motion and added resistance have better performances among these three kinds of side hull forms. Furthermore, there are local maximum and minimum points on the ship motion response curves due to heave and pitch coupling in their respective frequencies.
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