The study is related to adhesive-bonded long overlap double lap shear joints with thick adherends. The outer adherend is based on crossply carbon fibre/epoxy composite laminate and the inner adherend is mild steel. The paper aims to predict and assess the structural failure of the joint, including delamination of the composite and to determine the effects of the design parameters of adherend thickness, overlap length and fabric orientation on the joint’s failure. Both experimental and numerical methods were used for the analysis. The experimental programme includes fabrication, mechanical testing and failure examinations of various joints. The numerical methods are based on 2-D models using strength-limit and cohesive zone modelling methods, taking into consideration the composite properties of the plies and the resin layers separating them. The study showed a good agreement between the numerical and experimental results. Key conclusions in relation to the failure and design parameters of the joints are made.
CampilhoRDSGde MouraMFSFDominguesJJMS. Modelling single and double lap repairs on composite materials. Compos Sci Technol2005; 65: 1948–1958.
2.
McGeorgeD. Inelastic fracture of adhesively bonded overlap joints. Eng Fract Mech2010; 77: 1–21.
3.
WooleyGRCarverDR. Stress concentration factors for bonded lap joint. J Aircraft1971; 8: 817–820.
4.
AdamsRDAtkinsRWHarrisJA. Stress analysis and failure properties of carbon fibre in forced-plastic/steel double lap joints. J Adhesion1986; 20: 29–53.
5.
AdamsRDMallickV. A method for the stress analysis of lap joints. J Adhes1992; 38: 199–217.
6.
HarrisJAAdamsRD. Strength prediction of bonded single lap joints by nonlinear finite element methods. Int J Adhes Adhes1984; 4: 65–78.
7.
da SilvaLFMCarbasRJCCritchlowGW. Effect of material, geometry, surface treatment and environment on the shear strength of single lap joints. Int J Adhes Adhes2009; 29: 621–632.
8.
FeihSShercliffHR. Adhesive and composite failure prediction of single-L joint structures under tensile loading. Int J Adhes Adhes2005; 25: 47–59.
9.
RybickiEFKanninenMF. A finite element calculation of stress intensity factors by a modified crack closure integral. Eng Fract Mech1977; 9: 931–938.
10.
RajuIS. Calculation of strain energy release rates with higher order and singular elements. Eng Fract Mech1987; 28: 251–274.
11.
WimmerGSchueckerCPettermannHE. Numerical simulation of delamination in laminated composite components – A combination of a strength criterion and fracture mechanics. Compos Part B: Eng2009; 40: 158–165.
12.
BarenblattGI. The formation of equilibrium cracks during brittle fracture. General ideas and hypothesis, axially symmetric cracks. Prikl Mat Mekh1959; 23: 434–444.
13.
CuiWWisnomMR. A combined stress based and fracture mechanics based model for predicting delamination in composites. Composites1993; 24: 467–474.
14.
PetrossianZWisnomMR. Prediction of delamination initiation and growth from discontinuous plies using interface elements. Compos Part A: Appl Sci Manuf1998; 29: 503–515.
15.
CampilhoRDSGde MouraMFSFDominguesJJMS. Using a cohesive damage model to predict the tensile behaviour of CFRP single-strap repairs. Int J Solids Struct2008; 45: 1497–1512.
16.
KafkalidisMSThoulessMD. The effects of geometry and material properties on the fracture of single lap shear joints. Int J Solids Struct2002; 39: 4367–4383.
17.
JoussetPRachikM. Evaluation of elasto-plastic constitutive models for finite element analysis simulation of structural adhesives, Oxford: EURADH, 2008.
18.
HashimSA. Fabrication, testing and analysis of steel/composite DLS adhesive joints. J Ships Offshore Struct2011; 6: 115–126.
19.
NisarJAHashimSA. Meso-scale laminates adhesive joints for pultrusions. Int J Adhes Adhes2010; 30: 763–773.
20.
de MouraMFSF. Numerical simulation of the ENF test for the mode II fracture characterization of bonded joints. J Adhes Sci Technol2006; 20: 37–52.
21.
BS 7991:2001. Determination of the mode I adhesive fracture energy GIC of structure adhesives using the double cantilever beam (DCB) and tapered double cantilever beam (TDCB) specimens (2001).
22.
LefflerKAlfredssonKSStighU. Shear behaviour of adhesive layers. Int J Solids Struct2007; 44: 530–545.
23.
de MouraMFSFGoncalvesJPMChousalJAG. Cohesive and continuum mixed-mode damage models applied to the simulation of the mechanical behaviour of bonded joints. Int J Adhes Adhes2008; 28: 419–426.
24.
Pocius AV. Adhesion and adhesive technology: an introduction. Munich, New York: Hanser Publications, 1997.
25.
Kaw AK. Mechanics of composite materials. 2nd edition, New York: Taylor & Francis, 2006.
26.
da SilvaLFMde MagalhaesFACRGChavesFJP. ModeII fracture toughness of a brittle and a ductile adhesive as a function of the adhesive thickness. J Adhes2010; 86: 891–905.
27.
ClarkeJDMcGregorJ. Ultimate tensile stress over a zone: a new failure criterion for adhesive joints. J Adhes1993; 42: 227–245.
28.
GleichDMToorenVBeukersA. Analysis and evaluation of bond line thickness effects on failure load in adhesively bonded structures. J Adhes Sci Technol2001; 15: 1091–1101.
29.
Yahya NA and Hashim SA. Delamination of thick-adherend steel/CFRP laminate connections. The European Adhesion Conference (9th EURADH), Friedrichshafen/Germany, September 2012.
CampilhoRDSGBaneaMDPintoAMG. Strength prediction of single and double lap joints by standard and extended finite element modelling. Int J Adhes Adhes2011; 31: 363–372.
32.
CampilhoRDSGde MouraMFSFRamantaniDA. Tensile behaviour of three dimensional carbon epoxy adhesively bonded single and double-strap repairs. Int J Adhes Adhes2009; 29: 678–686.
33.
CamanhoPPDavilaCG. Mixed mode decohesion finite elements or the simulation of delamination in composite materials. NASA/TM2002; 211737: 1–37.
34.
KatnamKBCrocombeADKhoramishadH. The static failure of adhesively bonded metal laminate structures: A cohesive zone approach. J Adhes Sci Technol2011; 25: 1131–1157.
