Failure strength of e-glass/epoxy composite pinned joints: Effect of geometry, clamping torque and laminate orientation

The experimental investigations described in this paper were conducted in order to study the strength and failure behavior of composite plate with pin-loaded conditions. The main objective of the present paper was to investigate the influence of certain factors on the strength of the pin-loaded in E-GLASS/EPOXY composite plate with different orientations such as [0/90/+/-30]s and [0/90/+/-60]s. These factors included the preload moment (M=0, 2 Nm), the ratio of the edge distance to the pin diameter (E/D), and the ratio of the specimen width to the pin diameter (W/D). The mechanical properties and failure strengths of E-GLASS/EPOXY composite were obtained with experimental measurements. Based on experiments, the effects of laminate orientation, and preload moment on joint strengths were systematically investigated. In addition, geometrical configurations of specimens were suitably varied in order to observe all possible failure modes. A total of 150 different pin-loaded composite plate specimens were tested under static loading conditions. The specimen tested exhibited different failure modes, consisting of bearing, net-tension and shear-out, depending on the geometry adopted. Guidelines for effective laminate orientations, geometrical configurations and preload moment for mechanically pin connected E-GLASS/EPOXY composite plate were specified based on ultimate bearing strength. From the experiments, it was also found that glass-epoxy with. [0/90/+/-30]s yielded the highest bearing strengths. Bearing strengths reached when E/D and W/D ratios were equal or greater than 4 both [0/90/+/-30]s and [0/90/+/-60]s orientations. Besides, the experimental results showed that the load-displacement curve of specimen with M=0, had the lowest the failure strength. M=2Nm preload moment, had the maximum failure load.