Issue 29

M. Marino et alii, Frattura ed Integrità Strutturale, 29 (2014) 241-250; DOI: 10.3221/IGF-ESIS.29.21 245 steel plates with respect to the GFRP laminate allows to regard the testing system as statically equivalent to the central circular region undergoing perfectly fixed conditions on its boundary. At the center of that circular region of the laminated plate a circular hole with diameter D = 20 mm was considered, wherein a steel pin with diameter d D  was inserted and acted upon by a testing load parallel to the laminated plate. Different values of d were considered in [10]. In the present study, reference has been made to experimental results relevant only to the case d D  . The fiber volume fraction for the laminated plate was equal to about 60%, and the plate thickness was equal to 10 mm: 1 mm for each CSM layer and 1 mm for each mono-directional layer. This type of laminate is identified in the literature as “mono-directional”, despite the presence of two CSM layers, which can be treated as almost isotropic [11]. Bearing failure load, defined as the peak in the pin load-displacement curve, has been obtained in [10] for [0 ,90 ]     , observing that it is highly sensitive with  . N UMERICAL MODEL n order to simulate the failure mode and to evaluate the pin-bearing load of the laminated plate tested in [10], a 2D numerical model has been developed. A Matlab home-made code has been employed for the numerical analysis, with the use of the libraries encoded in the commercial solver Comsol Multyphysics for the finite-element computations and for managing the non-linear contact problem. The plate external boundary undergoes fully restrained conditions (see Fig. 2), in agreement with the experimental setting used in [10]. Due to the small thickness-to-side ratio of the plate and since the symmetric plying sequence of the laminate, the plane stress assumption has been enforced. Neglecting friction, the unilateral contact at the pin-plate interface has been treated through a surface-to-surface penalty method. Figure 1 : GFRP composite sample addressed in [10] (dimensions in mm). Figure 2 : Mesh details, loading conditions and laminate plying pattern employed for numerical simulations (on the left, pin is not shown). I