Structure Analysis of the Yacht under Wave Loads
Date Issued
2010
Date
2010
Author(s)
Lee, Chi-Fang
Abstract
When designing the structure of a yacht, we have to select the appropriate and reasonable design external loads to evaluate the structure of a yacht. Consequently, based on the speed of the target yacht when sailing, the researcher divides the external loads, a yacht may be suffered, into two types: (1) displacement wave pressure under low speed (2) planing wave pressure under high speed; afterwards, two appropriate software would be used to obtain these two external loads. In this paper, WASIM, which is developed by DNV Company, is used to obtain the displacement wave pressure, while nonlinear strip theory program, established by the ship motion lab in NTU ESOE, is employed to get the planing wave pressure. Two types of pressure mentioned are then applied to a finite element model of the target yacht to perform the dynamic structure analysis. Besides, the design pressure of the target yacht is also calculated according to ISO 12215-5 and DNV HSLC code. The results would be compared to the software ones and then be imposed to the finite element model to perform static structure analysis. The results of structure analysis demonstrate that all of the strains of the target yacht are all less than the allowable strain, which indicates the practicability of further weight deduction.
Regarding the finite element model of the target yacht, a generalized beam model is used to replace the actual establishment of the beam shape; however, when it comes to the beam strength evaluation, the beam is not the only element to be concerned, since the plate below plays a comparably important role as well, the width of the plate should be considered in generalized beam settings. As for the equivalent width of the plate, a formula is induced based on the survey of the 25 sample beams of the target yacht, in hope of providing future references to other researchers.
Subjects
structure of the yacht
displacement type wave pressure
planing type wave pressure
generalized beam
equivalent width of plate
ISO 12215-5
Type
thesis
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