A design study in crack patching

Jones, Rhys; Callinan, R. J.

doi:10.1016/0015-0568(81)90035-x

Cited by 54 publications

(22 citation statements)

References 6 publications

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“…Another important finding of the ref. [15] study was that in thin patches, the stresses over the flaw (in both the patch and the adhesive) are critical. However, as the patch thickness is increased, the shear stresses in the adhesive at the edges of the patch footprint become critical and may exceed allowable limits.…”

Section: Doubler Design Guidelinesmentioning

confidence: 99%

“…The important, fundamental results produced by Jones and Callinan in ref. [15][16] are worth reviewing in some detail in order to prepare for the damage tolerance discussions later in this report.…”

Section: Doubler Design Guidelinesmentioning

confidence: 99%

“…Ref. [15] showed that the adhesive stresses at the edge of the doubler can be reduced to admissible levels by stepping the thickness of the doubler from one or two plies at the outer perimeter to full thickness over a taper region. The length of the taper region is normally chosen to produce an edge taper ratio (taper depth-to-thickness increase ratio) of 10 to 30.…”

Section: Doubler Design Guidelinesmentioning

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%

“…[15] crack repair study used a unidirectional Boron-Epoxy laminate (fiber perpendicular to crack) as a baseline design. The study found that for patches that cover the entire length of the crack, a one ply (0.0057" thick) patch reduces the stress intensity factor to 33.5% of its value for the unpatched crack.…”

Section: Doubler Design Guidelinesmentioning

confidence: 99%

See 4 more Smart Citations

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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Section: Doubler Design Guidelinesmentioning

confidence: 99%

Section: Doubler Design Guidelinesmentioning

confidence: 99%

Section: Doubler Design Guidelinesmentioning

confidence: 99%

Section: Doubler Design Guidelinesmentioning

confidence: 99%

Section: Doubler Design Guidelinesmentioning

confidence: 99%

See 3 more Smart Citations

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

Roach¹,

Rackow²

2005

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The boundary element analysis of cracked stiffened sheets, reinforced by adhesively bonded patches

Salgado

Aliabadi

1998

Int. J. Numer. Meth. Engng.

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This paper presents a formulation based on the Dual Boundary Element Method and on the Dual Reciprocity Method for the analysis of thin cracked metal sheets to which thin metal patches and stiffeners are adhesively bonded.The stiffened cracked sheet is modelled with the Dual Boundary Element Method. Adhesive shear stresses are modelled as action-reaction body forces exchanged by the sheet and patches. The Dual Reciprocity Method is used to avoid the discretization of the patches attachment domain into internal cells.Several examples are presented to demonstrate the efficiency and robustness of the method developed. The examples include sheets with embedded or edge cracks, stiffened or not, to which single or double patches are adhesively bonded.1998 John Wiley & Sons, Ltd.

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Crack patching: design aspects

Jones¹

1988

Bonded Repair of Aircraft Structures

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A design study in crack patching

Cited by 54 publications

References 6 publications

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

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

The boundary element analysis of cracked stiffened sheets, reinforced by adhesively bonded patches

Crack patching: design aspects

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