Experimental study of failure and failure progression in T-stiffened skins

Co-curing/co-bonding techniques enabled significant reduction in part count and assembly time thus resulting in significant cost saving in the fabrication of stiffened composite structures. One of the major concerns in employing these structures has been the high susceptibility of the stiffeners debonding from the skin. Such failures have been more frequent under peel loads and necessitated the study of the behaviour of skin–stiffener joints in order to overcome these failures. Representative T-pull specimens made of carbon/epoxy material were tested at room temperature under peel load conditions to study the failure behaviour of skin/stiffener interface. Three design configurations compared in the present study are skin/stiffener configuration, configuration with capping strips/pads and configuration with capping strips/pads and overlay plies. This paper presents the failure initiation sites, path of failure propagation and final failure loads.