Adhesively bonded composite repair of metallic structures is one of the candidate technologies that has enormous potential in the ageing aircraft. A computational tool to analyse the repaired aerospace structure using an adhesively bonded composite patch is presented. This involves the three-layer technique based on the two-dimensional finite element method for adhesively bonded composite patch repair of cracked structures. This technique is capable of characterizing the crack growth and debond growth behaviour, as well as predicting the fatigue life extension of the repaired structure with a perfectly or imperfectly bonded patch. Also, the thermal effects which may develop during bonding or during service and the non-linear material behaviour of the adhesive are incorporated in this technique. The results from the three-layer technique show good agreement with experimental results as well as a previous investigator's published numerical results. Besides the accuracy of the technique, the advantage of the two-dimensional three-layer technique is cost-effectiveness when compared with the three-dimensional finite element or performing expensive experiments on various patch configurations for design purposes. An overview of the three-layer technique to investigate a cracked metallic plate repaired with bonded composite patch is presented in this paper.
RatwaniM. M.Characterization of fatigue crack growth in bonded structures-analysis of cracked bonded structures. Report AFFADL-TR-31, Vol. II, Air Force Flight Dynamics Laboratory, July 1977.
7.
RatwaniM. M.Characterization of fatigue crack growth in bonded structures-crack growth prediction in bonded structures. Report AFFADL-TR-77–31, Vol. 1, Air Force Flight Dynamics Laboratory, July 1977.
8.
TongP.PianT. H.H.LasryS. J.A hybrid element approach to crack problems in plane elasticity. Int. J. Numer. Meth. Engng, 1973, 7, 297–308.
9.
RoseL. R. F.An application of the inclusion analogy for bonded reinforcements. Int. J. Solids Structs, 1981, 17, 827–838.
10.
RoseL. R. F.A cracked plate repaired by bonded reinforcements. Int. J. Fracture, 1982, 18, 135–144.
11.
MukiR.SternbergE.On the stress analysis of overlapping bonded elastic sheets. Int. J. Solids Structs, 1968, 4, 75–94.
12.
SunC. T.ArendtC.Bending effects of unsymmetric adhesively bonded composite repairs on cracked aluminum panels. In Proceedings of the FAA-NASA International Symposium on Advanced Structural IntegrityMethods for Airframe Durability and Damage Tolerance, Hampton, Virginia, 4–6 May 1994, Vol. 1, pp. 309–315.
13.
SunC. T.KlugJ.ArendtC.Analysis of cracked aluminum plates repaired with bonded composite patches. Am. Inst. Aeronaut. Astronaut. J., 1996, 34 (2), 369–374.
14.
BakerA. A.Repair efficiency in fatigue-cracked aluminium components reinforced with boron/epoxy patches. Fatigue Fracture Engng Mater. Structs, 1993, 16, 753–765.
15.
ChueC. H.ChangL. C.TsaiJ. S.Bonded repair of a plate with inclined central crack under biaxial loading. Composite Structs, 1994, 28, 39–45.
16.
PooleP.LockD.YoungA.Composite patch repair of thick aluminum alloy sections. In Proceedings of the International Conference onAircraft Damage Assessment and Repair, Melbourne, Australia, August 1991, pp. 85–91.
17.
PooleP.StoneM. H.SuttonG. R.Effect of adhesive bonded variables on the performance of bonded CFRP patch repairs of metallic structures. In AGARD Conference Proceedings, 1986, Vol. 402, pp. 9.1–9.21.
18.
DenneyJ. J.MallS.Effect of disbond on fatigue behavior of cracked aluminum panel with bonded composite patch. In Proceedings of the 37th AIAA-ASME-ASCE-AHS-ASC Conference onStructures, Structural Dynamics, and Materials, Salt Lake City, Utah, 15–17 April 1996, Vol. I, pp. 14–21.
19.
DenneyJ. J.MallS.Characterization of disbond effects on fatigue crack growth behavior in aluminum plate with bonded composite patch. Engng Fracture Mechanics, 1997, 57 (5), 507–525.
20.
ConleyD. S.Fatigue response of repaired thick aluminum panels with bondline flaws. Master's thesis, Department of Aeronautics and Astronautics, Air Force Institute of Technology, Wright-Patterson Air Force Base, 1999.
21.
SchubbeJ. J.MallS.Investigation of cracked thick aluminum panel repaired with bonded composite patch. Engng Fracture Mechanics, 1999, 63 (3), 305–323.
22.
FredellR. S.Damage tolerant repair techniques for pressurized aircraft fuselages. PhD thesis, Delft University of Technology, Delft, The Netherlands, 1994; also in Report WL-TR-93–3134, 1993.
23.
FredellR. S.ConleyD. S.KnightonS.Design development of a bonded fuselage repair for C-5A. In Proceedings of the 1995 USAF Structural Integrity Program Conference, San Antonio, Texas, December 1995, pp. 887–902.
24.
FredellR.BarneveldW. V.VlotA.Analysis of composite patching of fuselage structures: High patch elastic modulus isn't the whole story. In Proceedings of the 39th International SAMPE Symposium, Anaheim, California, 11–14 April 1994, Vol. 1, pp. 610–623.
25.
NaboulsiS.MallS.Modeling of cracked metallic structure with bonded composite patch using three layer technique. Composite Structs, 1996, 35, 295–308.
26.
NaboulsiS.MallS.Thermal effects on adhesively bonded composite patch repair of cracked aluminum panels. Theor. Appl. Fracture Mechanics, 1996, 26, 1–12.
27.
NaboulsiS.MallS.Characterization of fatigue crack growth in aluminum panels with bonded composite patch. Composite Structs, 1997, 37, 321–334.
28.
NaboulsiS.MallS.Fatigue crack growth analysis of adhesively repaired panel using perfectly and imperfectly composite patches. Theor. Appl. Fracture Mechanics, 1997, 28, 13–28.
29.
NaboulsiS.MallS.Nonlinear analysis of bonded composite patch repair of cracked aluminum panels. Composite Structs, 1998, 41, 303–313.
30.
NaboulsiS.MallS.DenneyJ. J.Crack growth in imperfectly bonded composite patch repairs of crack aluminium panels. In Proceedings of the 19th International Committee onAeronautical Fatigue, 16–20 June 1997, pp. 639–655.
31.
RybickiE. F.KanninenE. F.A finite element calculation of stress intensity factors by a modified crack closure integral. Engng Fracture Mechanics, 1977, 9, 931–938.
32.
WhitcombJ. D.Three-dimensional analysis of a postbuckled embedded delamination. J. Composite Mater., 1989, 23, 862–889.
33.
WhitcombJ. D.Three-dimensional analysis of a postbuckled embedded delamination. Technical publication NASA TP 2823, National Aeronautics and Space Administration, July 1988.
34.
JonesR.CallinanR. J.Thermal considerations in the patching of metal sheets with composite overlays. Int. J. Solids Structs, 1980, 8 (2), 143–149.
35.
CherryM. C.Investigation of residual strength and fatigue life of unstiffened aluminum panels with multiple site damage. Master's thesis, Department of Aeronautics and Astronautics, Air Force Institute of Technology, Wright-Patterson Air Force Base, 1995.
36.
KlugJ.SunC. T.Large deflection effects of cracked aluminum plates repaired with bonded composite patches. Composite Structs, 2000 (in press).
37.
Finite Element Programs; ABAQUS/Standard 5.6, 1996 (Hibbitt, Karlsson and Sorensen, Pawtucket, Rhode Island).
38.
DenneyJ. J.Fatigue response of cracked aluminum panel with partially bonded composite patch. Master's thesis, Department of Aeronautics and Astronautics, Air Force Institute of Technology, Wright—Patterson Air Force Base, 1995.
39.
BakerA. A.Fatigue crack propagation studies on aluminum panels patched with boron/epoxy composites. In Proceedings of the International Conference onAircraft Damage Assessment and Repair, Melbourne, Australia, August 1991, pp. 209–215.
