Composites repair techniques

Table 4.35 Summary of Available Composite Repair Techniques ...

Alexander (2007) and Alexander and Ochoa (2010) performed experiments in conjunction with FEA and based on the obtained results presented an innovative design to extend the existing composite repair techniques to offshore pipes. Their research led to an easily deployable CFRP repair system based on the limit analysis method and strain-based design techniques. 

This repair technique was further illustrated using a damaged F/A-18 horizontal stabilator (Jones et al. [2]). The work was performed as part of the Composite Repair Engineering Development Program (CREDP) which is a joint program between the Canadian Forces, the Royal Australian Air Force and the United States Navy. The stabilator described in the report was initially classed as unserviceable and irreparable due to two fragment strikes from a tracer rocket. 

A relatively new repair technique for concrete structures, including prestressed structures, consists of externally bonding flexible sheets of FRP composites to the concrete surface. Depending on the type of application, the function of the externally bonded reinforcement... 

To prevent ALWC, the use of coatings such as coal tar epoxy or glass flake composite along with application of CP has been recommended [16]. Although replacing piles which are beyond economic repair can always be an option, the repair techniques that can normally be applied are one or a combination of the following [18] ... 

Selecting the appropriate repair technique is an important decision which requires an understanding of the risks and rewards associated with each composite repair alternative and material architecture. Safety, permanency, and effectiveness are the primary drivers of this decision, but cost can also become an important issue. 

Composites, like Clock Spring , compete with older, more widely accepted welded repair techniques. These new repair options offer advantages over the more traditional repairs and are both more cost-effective and also the safest repair alternative. 

Lee, W.-Y., Lee, J.-J., 2004. Successive 3D FE analysis technique for characterization of fatigue crack growth behavior in composite-repaired aluminum plate. Composite Structures 66, 513-520. 

This chapter will first outline the conventional offshore riser repair techniques and their limitations which, in turn, provide the motivation for adoption of composite repair. A brief discussion about the application of FRPC in pipeline repair, its limitations, current practices, and material types will be given. A subsequent section provides information on the industrial design and safety standards used in designing and assessing the performance of offshore risers, corroded pipelines, and pipelines repaired with FRPC. The typical loading conditions of an offshore riser are also discussed so that the requirements of CRS can be understood. 

Alexander, C., April—May 2012. Design of an optimized composite repair system for offshore risers using integrated analysis and testing techniques. In Offshore Technology Conference. http //dx.doi.org/10.4043/23164-MS. 

Freire, J.L.F., Vieira, R.D., Diniz, J.L.C., Meniconi, L.C., 2007. Part 7 effectiveness of composite repairs applied to damaged pipeline. Experimental Techniques 31, 59—66. 

While the benefits of composite repairs are well known, eurrent recommended quality control procedures and inspection techniques stdl leave mueh to be desired. Most composite repair contractors propose hardness measurement as well as visual inspection however, more rehable and less skill-dependent techniques are required. Enhanced efforts to develop field quahty control and inspection techniques wiU, among other factors, determine the level of growth in the use of composite repairs in the industry. 

There are various reasons to study the composition of ancients cements. The actual composition of a cement, for example, provides information on its nature, the technology used for making it, and the provenance of its components (Middendorf et al. 2005). It may also elicit differences between the nature of an original cement used for building and that used for later repairs (Streicher 1991 Jedrzejewska 1990). Most analytical work concerning ancient cement in the recent past has been based mainly on the use of optical microscopy and classical analysis techniques. Sometimes, such studies are complemented with information derived by instrumental techniques (Blauer-Bohm and Jagers 1997). 

Early research on high temperature polymers concentrated primarily on thermal stability and paid little attention to their processability and cost. However, for a polymer to be successful as a c< miercially viable structural matrix, it must exhibit a favorable combination of processability, performance characteristics, and price. In particular, a desirable high temperature polymeric system for coatings, composites, and adhesives applications must exhibit adaptability to conventional processing techniques at low temperature and pressure, should exhibit good mechanical properties, acceptable repairability, weatherability, and cost effectiveness. 

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