Failure Analysis of Bolted Aluminum Sandwich Composite Plates under Compressive Preload

Abstract

The aim of this study is to examine the failure load and failure mode in an aluminum— glass-epoxy sandwich composite plate fastened mechanically by a bolt and washers on a circular hole under a preload exerted by a moment. Parametric studies were performed by experiments to find out the effects of joint geometry and preload moment on the failure strength and failure mode. The preload moments chosen (M) were 0, 3 and 6 Nm while the end distance to hole diameter (E/D) and width to diameter (W/D) ratios were chosen as 1—5 and 2—5, respectively. It is concluded from these experiments that the failure load increases with the increase of M, E/D and W/D. When M, E/D and W/D ratios reach 3—6, 2—5 and 5 Nm, full bearing strengths occur, respectively. When E/D = 1 for all the widths and preload moments, the shear-out failure mode is observed. The mixed modes, especially bearing and net-tension, are observed for E/D and W/D equal to 2—5 and 3—4, respectively. The preload moments increase the failure strengths of the composite laminate.