An Experimental and Numerical Investigation of the Mixed-mode Fracture Toughness and Lap Shear Strength of Aerospace Grade Composite Joints

摘要

The increasing use of composite materials in variousindustries, such as aerospace, automotive and renewableenergy generation, has driven a need for a greater understandingof the fracture behaviour of bonded compositejoints.An important prerequisite for the adhesive bonding ofcomposites is the existence of a uniform surface free fromcontaminants and mould release agents. While there areseveral ways in which this may be achieved, the use ofpeel plies has emerged as the preferred choice for manyindustries due to the repeatable nature of the resulting surface,particularly in the highly regulated aerospace industry.However, the use of peel plies can present some problems.It is possible that contamination from the peel plycan be transferred to the composite substrate and adverselyaffects the adhesive joint [1].Composite joints are typically evaluated using lapshear type tests. While these tests are relatively simple toperform and post-process compared to their fracture mechanicsbased counterparts, the results can often be misleadingand are greatly dependent on the overlap length,the thickness of the substrate and the type of fillet employed[2, 3].The aim of this work is to show that composite jointsystems can be modelled using material properties determinedfrom fracture mechanics based tests. The fractureparameters will be used to develop numerical models of the fracture tests that accurately predict the wide-area lapsheartest.