Bonded patch repair

Figure 1.8 A composite fuselage panel with bonded patch repairs. Courtesy of AMRC with Boeing, Sheffield, UK.

Soutis and Hu (1997) studied numerically and experimentally bonded composite patch repairs to repair cracked aircraft aluminum panels. The authors concluded that the bonded patch repair provides a considerable increase in the residual strength. 

Bonded patch Flat or curved surface field repair Not suitable for high temperature or critical parts Fast but depends on cure cycle of adhesive Low to medium... 

Local repair of bonded structure damage from mechanical sources (bird-strike, equipment impact, etc.) can either be bonded or mechanically fastened patches. In general it is more likely that sandwich structure is repaired using bonded patches because of the limited compression capability of sandwich structure and the risk of introducing water into the honeycomb from penetrating fasteners. 

Koh YL, Chiu WK, Rajic N, Galea SC. Detection of disbond growth in a cyclically loaded bonded composite repair patch using surface-mounted piezoceramic elements. Struct Healih Monit Int J 2003 2(4) 327-39. 

The choice of patch repair material is discussed later. Wetting or bonding agents are used to promote adhesion between the repair and the original... 

Some proprietary patch repair materials include bonding agents. These should be avoided in electrochemical rehabilitation work. They may help where a high standard of workmanship is difficult to achieve, but they often require that the patch is applied at the right time when the bonding agent is ready. This can be difficult to do on site and adequate supervision is necessary to ensure that correct application is achieved. 

The second part of this book is devoted to current and potential applications of adhesive materials in construction. Chapter 6 deals with both the repair and the strengthening of concrete structures, covering applications ranging from non-structural patch repairs and resin overlays to externally bonded steel plate reinforcement. The theme of repair and strengthening is extended to applications involving steel, timber and masonry structures. A number of case histories are reviewed and discussed with reference to the successes and failures, and the results of allied research work are presented. In Chapter 7 a number of applications of adhesives in new construction are described, and specific examples are given. The final chapter. Chapter 8, examines the potential for future developments in adhesive usage. 

Although not strictly used as prime structural adhesives, polymer latices or dispersions have been included here because of their increasing use as aids to bonding in the patch repair of spalled concrete. They usually take the form of a polymer-cement slurry which is applied to the moistened and prepared concrete surface. In general, the repair mortar must then be applied before a film... 

Aggelopoulos, E. S., Righiniotis.T. D. andChryssanthopoulos, M. K. (2011), Debonding of adhesively bonded composite patch repairs of cracked steel members . Composites Part B Engineering, Vol. 42, Issue 5, July 2011, pp. 1262-1270. 

Epoxy adhesives are widely used in most industries for the structural bonding of most types of materials (metals, wood, plastics, composites, ceramics, glass, concrete, masonry, etc). Primers may be recommended for some materials. They are also used to repair structures bonding patches and crack-filling. Some adhesives are specifically designed for aerospace applications or specialised mechanical and electrical assembly. 

Speth DR, Yang YP, Ritter GW (2010) Qualification of adhesives for marine composite-to-steel applications. Int J Adhes Adhes 30(2) 55-62 Tamblin JS, Yang C, Harter P (2001) Investigation of thick bond line adhesive joints. DOT/FAA/AR-01/33 Turton TJ, Dalzel-Job J, Livingstone F (2005) Oil platforms, destroyers and frigates — case studies of QinetiQ s marine composite patch repairs. Compos A 36 1066-1072... 

Additional information such as material and bonding properties between steel and composite can be obtained by reviewing literature related to composite patch repair on a steel structure. A comprehensive amount of studies have been conducted and can be used as a basis to model the bonding between the composite repair material and steel riser. 

Internal repair systems using earbon and glass fibre (GF) composites were reviewed and evaluated by Bmee et al. (2006). Carbon fibre (CF) liner repair was seen as the more promising proeess, having better strength and stiffness characteristics than GF liners. However, the developed and investigated CF liner systems were patch repair only (sectional liners) and bonded to the steel pipelines. The details of these tests are discussed in the following sections. 

One issue with the GBS treatment (and silane-coupling treatments, in general) is that the performance can be highly dependent on processing conditions, especially hydrolysis and drying conditions. Nonetheless, process controls suitable for field application of bonded repair patches are possible. 

The processes used to prepare and bond repair patches are more difficult... 

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