City Research Online

Abstract

This chapter describes the application of adhesively bonded fibre composites to repair or reinforce highly loaded structures. Although the focus is mainly on patch repair of primary metallic or composite airframe structures suffering, respectively, from fatigue cracking or mechanical damage, it is equally applicable to demanding nonaircraft repairs and to other types of damage. While the use of adhesive bonding to attach repair patches is highly advantageous when compared with mechanical fastening, it is challenging for several reasons. Due to the current inability of nondestructive inspection procedures to detect weak bonds in practical situations, the greatest concern is in obtaining airworthiness certification, since for repairs to primary structure confidence must be provided that the risk of patch disbonding is extremely low. To meet this requirement, alternative approaches for assessing the initial and ongoing structural integrity of the adhesive bond are outlined, based on proof testing and/or structural health monitoring. The use of composite reinforcement to extend the fatigue life of primary metallic components by reducing strain in areas of local strain concentration is generally less critical than repairs so potentially easier to certify. Adhesively bonded reinforcements can be applied, for example, to rectify fatigue-prone design features (‘hot spots’), reduce stress on welded repairs, and restore strength or stiffness that is lost by corrosion damage.

Publication Type:	Book Section
Publisher Keywords:	Repairs; Airframes; Metals; Composites; fatigue; disbonding; SHM; certification
Subjects:	T Technology > TJ Mechanical engineering and machinery
Departments:	School of Science & Technology > Engineering

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