The aim of this study was to reduce the weight of the world’s tallest aluminum mast for a new series of single mast sailing yachts manufactured by Perini Navi under the brand name Salute. The planned mast had a length of 140 to 168 feet (50 to 60 meters) high and needed to account for all the requirements related to structural instability, in order to ensure the best performance under operational conditions. As a result of our virtual optimization, the weight of the mast was reduced by around 20% with respect to the original specifications.
The objective was to find the optimal mast weight under specific structural strength requirements to avoid global and local buckling. The mast weight reduction and the parametric modeling allowed the evaluation of a correlated reduction of keel weight needed for counter balance. The keel and rudder lines were modified to improve the yacht’s stability in keeping with the higher center of gravity resulting from the tall mast.
We first analyzed the global buckling factors on transverse and longitudinal planes. EnginSoft created three different parametric models starting from an initial model developed by Perini Navi in ANSYS:
It was now time to take an integrated approach to these three models. We used modeFRONTIER to integrate the procedures of these three models into an automated optimization loop. Within this new framework, the variables were automatically processed to improve the project configurations. The optimization problem consisted of: 35 geometric variables; 8 constraints; 3 objectives (two buckling factors and weight).
The optimization strategy used: an initial well-spread population created using a Sobol sampling; MOGA-II, a multi-objective genetic algorithm, to reach the best global results.
Creating a mathematical model of the mast brought clear advantages to this project. Savings included:
EnginSoft’s contribution to the development of this new simulation methodology at Perini Navi was made possible thanks to our extensive experience in three specific fields: parametric numerical modeling; multi-disciplinary optimization; expertise in the integration and automation of software simulation in the design process.
The FE model, including complex nonlinearities due to high deformations (for the initial preloading), and cable-shrouds (reacting only under tensile stress)
The mast buckling analysis: the preload due to cable tightening was modeled using an initial stress, followed by a linear buckling analysis
modeFRONTIER provides a seamless coupling with third party engineering tools, enables the automation of the design simulation process, and facilitates analytic decision making.
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