Designing for damage-tolerant composite repairs

Chiu, Wing Kong; Rees, D.; Chalkley, Peter; Jones, Rhys

doi:10.1016/0263-8223(94)90003-5

Cited by 28 publications

(8 citation statements)

References 14 publications

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“…thirty eight wings with a total of seventy six doublers, there are two doublers per wing) were successfully proof loaded in the US and a further two wings passed a proof load test in Australia [14]. This led to an enunciation of the failure mechanisms for bonded composite joints and repairs to both civil infra-structure and military [15,16,17] and civil transport aircraft [19] and to the development of validated design criteria for composite repairs [17,18,19]. Figure 4 presents a typical failure surface associated with boron epoxy repairs to aluminium structures, from [15].…”

Section: First Ply Failurementioning

confidence: 99%

Composite repairs to bridge steels demystified

Ali

Raman

Zhao

et al. 2017

Composite Structures

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Section: First Ply Failurementioning

confidence: 99%

Composite repairs to bridge steels demystified

Ali

Raman

Zhao

et al. 2017

Composite Structures

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“…The peak adhesive shear stress was less than 25 MPa and was below the endurance level of the thin film adhesive FM73, see 130], indicating that the repair should not debond and should be inherently damage tolerant, see [30]. The stress concentration around the damage was also found to be very localised and was consistent with the experimentally measured thermal emission profile [29], as well as with the experimentally measured values of strain and compliance.…”

Section: Reduction In Strain Due To An External Doublermentioning

confidence: 53%

Residual strength of composites with multiple impact damage

Jones

1994

Composite Structures

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“…This indicates that there was little deterioration in the bond strength over this time. Normal repair methodologies that utilize doubler stiffness ratios of 0.8 to 1.0, would produce load transfer ratios in the 40-60% range [6,19,20]. However, since this repair has a lower stiffness ratio of 0.3, the resulting stresses in the doubler are higher as shown in the graphs.…”

Section: The Curves Indicate That the Load Transfer Into The Doubler mentioning

confidence: 99%

“…Thus, an increased emphasis is placed on quantifying the probability that a flaw of a particular size and location will be detected by a piece of NDT equipment. In addition to this report, detailed discussions on general damage tolerance assessments for structural repairs are presented in references [15][16][17][18][19][20].…”

Section: Doubler Design Guidelinesmentioning

confidence: 99%

Development of bonded composite doublers for the repair of oil recovery equipment.

Roach¹,

Rackow²

2005

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An unavoidable by-product of a metallic structure's use is the appearance of crack and corrosion flaws. Economic barriers to the replacement of these structures have created an aging infrastructure and placed even greater demands on efficient and safe repair methods. In the past decade, an advanced composite repair technology has made great strides in commercial aviation use. Extensive testing and analysis, through joint programs between the Sandia Labs FAA Airworthiness Assurance Center and the aviation industry, have proven that composite materials can be used to repair damaged aluminum structure. Successful pilot programs have produced flight performance history to establish the durability of bonded composite patches as a permanent repair on commercial aircraft structures. With this foundation in place, this effort is adapting bonded composite repair technology to civil structures. The use of bonded composite doublers has the potential to correct the difficulties associated with current repair techniques and the ability to be applied where there are no rehabilitation options. It promises to be cost-effective with minimal disruption to the users of the structure. This report concludes a study into the application of composite patches on thick steel structures typically used in mining operations. Extreme fatigue, temperature, erosive, and corrosive environments induce an array of equipment damage. The current weld repair techniques for these structures provide a fatigue life that is inferior to that of the original plate. Subsequent cracking must be revisited on a regular basis. The use of composite doublers, which do not have brittle fracture problems such as those inherent in welds, can help extend the structure's fatigue life and reduce the equipment downtime. Two of the main issues for adapting aircraft composite repairs to civil applications are developing an installation technique for carbon steel and accommodating large repairs on extremely thick structures. This study developed and proved an optimum field installation process using specific mechanical and chemical surface preparation techniques coupled with unique, in-situ heating methods. In addition, a comprehensive performance assessment of composite doubler repairs was completed to establish the viability of this technology for large, steel structures. The factors influencing the durability of composite patches in severe field environments were evaluated along with related laminate design issues.

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Designing for damage-tolerant composite repairs

Cited by 28 publications

References 14 publications

Composite repairs to bridge steels demystified

Composite repairs to bridge steels demystified

Residual strength of composites with multiple impact damage

Development of bonded composite doublers for the repair of oil recovery equipment.

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