PSI - Issue 24

Pierluigi Fanelli et al. / Procedia Structural Integrity 24 (2019) 949–960 Pierluigi Fanelli et al. / Structural Integrity Procedia 00 (2019) 000–000

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This allow the global loads to be calculated considering the loads applied in the di ff erent FE analyses ( L FE ) multi plied by the corresponding factors in v -vector. This leads to the calculation of the five global loads for each timestep obtained by the FBG network:

L i

Real = L i

FE · v i

(3)

The computation time is very low; this is related to the fact that the elements of χ -matrix are known and constant for each calculation timestep, which gives the possibility of inverting the matrix in advance. On the other hand, the FE simulation, which could be considered as the most time-expensive phase of the method, is required once. Consequently, it can be said that this method could become the base of a fast-algorithm for real-time loads calculation; this could lead to the idea of online systems, designed to give real-time information about the acting loads and the trim of the ship.

3. Numerical model of the ship hull

The main goal of this paper is to demonstrate the suitability of the global loads reconstruction method for high sti ff ness ship hulls, such as the one typical of powerboats; this leads to the choice, for the experimental tests, of a CUV 40 (Fig.1) powerboat, which can run at 125 km / h during a race, continuously impacting on the free surface of water. For this reason, the aluminum hull is designed to ensure an high sti ff ness.

Fig. 1. The analyzed CUV 40 powerboat

The boat is made in aluminum with E = 70 GPa, ν = 0.33 and ρ = 2700 kg / m 3 . The external geometry of the boat has been initially acquired from a laser scan and then edited to obtain regular surfaces. The superior part of the boat and the stern have been modeled with image recognition techniques and direct measuring on the boat. The internal geometry is very complex and represents the frame of the boat. The aluminum components give sti ff ness to the boat and are welded together one each other and to the hull. In the model are present 4 di ff erent types of components: the longitudinal beams, that run from the stern to the bow directly welded on the hull surface; the transversal ribs,