Design and failure analysis of composite bolted joints for aerospace composites

McCarthy, M.A. McCarthy University of Limerick, Limerick, Ireland 

This chapter presents both experimaital and finite element approaches that are commonly used to assist in the design and failure analysis of composite bolted joints. The work presented mostly stems from the authors work in the field over the past decade. Results from both local (i.e. detailed) finite element and global (Le. efficient) closed form and finite element approaches are presented, and expmmental results from the open literature are used to both calibrate and validate the modelling procedures. The primary variable under consideration is bolt-hole clearance, which is chosen as it induces significant three-dimensional stresses into the joint, and significandy alters the bolt-load distribution in multi-bolt joints, and so provides a rigorous test case for analysis. 

Polymer Composites in the Aerospace Industry. http //ds .doi.oi l0.1016/B978-0-85709-523-7.00011-6 

As mentioned, large commercial aircraft contain about three million fasteners, and so a multitude of bolted joint configurations exist. However, despite this diversity, there is a basic commonality in the stresses set up by the fastener or bolt load at a particular bolthole, and the effect of other loaded bolt-holes on this stress distribution [1], This allows simplified coupon tests to be used in establishing design criteria and data for these various joint configurations. The intent is to then combine a suitable number of test/ model results to represent the actual situation. 

In this work, all joints were fabricated using a carbon fibre/epoxy composite material manufactured by Hexcel composites, with designation HTA/6376. In the single-bolt and three-bolt, single-lap joints, both laminates had a quasi-isotropic layup with stacking sequence [45/0/-45/90]5s. Each ply had a thickness of 0.13 mm, yielding a total laminate thickness of 5.2 mm. In the double-lap three-bolt joints, the splice plates were manufactured from 16 plies, giving a nominal thickness of 2.08 mm, while the 

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Design and failure analysis of composite bolted joints for aerospace composites... 

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