Failure maps to assess bearing performances of glass composite laminates

Aim of this article is the assessment of the bearing mechanical performances of pin-loaded glass laminates as function of their geometrical configuration. To this concern, 32 specimens having different hole diameter (D), laminate width (W), and hole center to laminate free edge distance (E) have been tested under bearing conditions. The maximum bearing stress and the stress-displacement curves were analyzed as function both of hole to laminate free edge distance E and hole diameter D. Moreover, an experimental 2D failure map was created by placing the experimental results (i.e., the kind of failure mechanism occurred for each geometrical configuration) in the plane E/D versus W/D ratios. In order to identify a simplified methodology able to design mechanically fastened joints in an easy and effective way, a simplified theoretical failure map on E/D and W/D axes was proposed. The theoretical model showed a good matching with the experimental results validating the proposed approach. In particular, the proposed simplified failure map highlighted that woven glass fiber composite laminates fastened joints should have E/D and W/D ratios higher than 1.6 and 2.1, respectively, in order to stimulate a progressive bearing failure mechanism and achieve the full laminate strength. Finally, another goal of this article was to assess failure mechanisms evolution by drawing a 3D plot (i.e., at varying E/D and W/D geometrical ratios) of the failure index evaluated for each failure mechanism according to the maximum stress criterion.