PSI - Issue 24

Alessandro Castriota et al. / Procedia Structural Integrity 24 (2019) 279–288 A. Castriota et al. / Structural Integrity Procedia 00 (2019) 000 – 000

283

5

The panel was mounted on steel contrast structures and on structures that reproduce the necessary constraints, consistently with the indication shown in the numerical model. Load was applied through a 500 kN servohydraulic actuator in load control, up to failure (Fig 4).

(a)

(b)

Fig. 4. Experimental set-up: (a) side view; (b) top view

The test performed in three different steps. A first step, in which load was applied up to 30% of the load P followed by an unloading phase, allowed verifying the correctness of the experimental set-up. The second step, until reaching P, was achieved without obtaining the failure of the component; therefore, after an unloading phase, the final load step was carried out, in which the load was applied until the failure due to the local instability of the panel. The test was monitored with camera and all data were recorded at a frequency of 10 Hz. A Moiré projection technique was also used to enhance out-of-plane displacements around the cut.

5. Discussion of results

5.1. Experimental results

From the reading of the strain gauge data, it can be seen how the load is distributed fairly evenly on the load section, with modest variations indicating the presence of a slight bending distribution. From the observation of the component, it noticed how this difference in the strain gauge readings was due to a slight curvature in the longitudinal direction proper to the panel. Fig. 5a shows some comparisons between the deformations of the two sides of the panel at the end of second step, when the reference load P is applied. All data are normalized to the maximum measured strain, due to privacy reasons. The comparison showed that the applied load is well centered and do not introduce relevant eccentricities, with the exception of the differences introduced by the imperfection of the panel geometry. Due to the clearance existing in the load train, as showed in Fig. 5b, the initial slope of the unloading phase was used to determine the panel stiffness.