EnginSoft as innovation partner in the optimization study of the highest aluminium sailboat main mast for Perini Group

Perini sailboats have been always acknowledged high performances in terms of balance, speed, reliability and safety, paying a special attention to aesthetic details and comfort.
Such distinguishing and well-consolidated features are combined with constant improvement in technical solutions and in a widening range so to meet the customers' growing requirements.

Considering such context, a pilot project has been developed, taking advantage of automatic optimization techniques based on virtual prototyping.
In order to carry out a really meaningful project from the company point of view, some important aspects have been taken into account, such as the choice of a sector with a considerable know-how able to provide at the same time positive and direct productive implications, though coming from a typical R&D activity.

Going into this project details, born of Perini and EnginSoft collaboration, it concerns the optimization of the main mast structural part of a new sailboat special series.
The study aims at the identification of the best solution able to guarantee the combination of the lower weight with certain buckling factor, both globally and locally.
The accurate FEM scaling implies not only a weight reduction in the mast structure but also more the 5-7 times saving in the keel one, thus increasing the sailing performance of the boat.

Further important implications are the considerable savings due to the high cost of high resistant aluminum and lead alloys used for the keel, an easier product construction thanks to a reduction in plate weight and thickness, a shorter time-to-market (reducing the time for plate welding and assembly), easier mastings, greater sail comfort, thanks to a reduction in heeling performance being equal.

The design methodology consists of the analysis of the first (global) buckling factors on the transverse and symmetry plane.
The model has been totally created in Workbench using DesignModeler and including link elements through command. The model consists of LINK10 for shrouds and stays, BEAM188 for mast panels and crosstrees, while the connection between the panels and the crosstrees through cp has been carried out via command.

The information concerning the mast section properties, for its six parts in terms of inertia and area, have been parametrically included in the model within the real constants.

The section model for the six parts has been worked out and parameterized in Workbench. The variation of the geometric parameters, which define the shape of the section, identifies a values range for the area and the inertia moments of the section. Such values are the input ones used for the above-mentioned global model.

To carry out the analysis of both global and local buckling, the prestress effects due to the falls have been taken into account.
On such regard, a first prestress static analysis has been set, followed by a linear buckling analysis.
The integration procedures of the three Workbench models and the associated optimization process have been developed within the modeFRONTIER platform (a multi-objective optimization software).

The variables, that modeFRONTIER has automatically processed in order to improve the project configurations, are the same geometric parameters the designer normally acts on, according to its experience.

In fig. 6 is presented the workflow created in modeFRONTIER, where the three Workbench models (the section one, the global buckling one and the local buckling one) are referred to and jointly managed.
An integration process as such obviously has a certain impact on the previous design methodology, imposing on one hand a parametric set effort under strict requirements, but guaranteeing on the other hand, the exploitation of the whole available potential of the ANSYS software in the Workbench interface.

Workbench has in fact allowed the robust regeneration of the numerical model, according to the variation of the input parameters, the automatic application of the boundary conditions, the automatic recognition of the contact areas, the possibility of carrying out advanced elaboration through pre- and post-processing commands.

Fig. 4 - sezione dell'albero realizzata in ANSYS Workbench	Fig. 5 - Modello per buckling locale dell'albero

Thanks to ANSYS versatility features, it has been possible to adjust an extensive optimization process. The results, achieved both in terms of effective structure lightening and material and time saving during machining, explain better than words the following choice by Perini to widen ANSYS Workbench application to other design protocols, such as the detailed check of some structural components.

Fig. 6 - Workflow di analisi

The advantage is really notable: the created model can be applied to similar structures and can be further detailed and adjusted to different requirements for the benefit of efficiency, reliability and after all of a real product and process development.

Fig. 6 - Campo tensionale a seguito del precarico

Fig. 7 - Forme di buckling globali e locali