Effect of Adhesive Bonding Variables on the Performance of Bonded CFRP Patch Repairs of Metallic Structures,
ROYAL AIRCRAFT ESTABLISHMENT FARNBOROUGH (ENGLAND)
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The literature is briefly reviewed and limitations of the existing experimental data on the performance of bonded CFRP patches are indicated. Earlier work form the Royal Aircraft Establishment is summarized., showing the importance of patch size and crack growth conditions prior to patching. Fatigue data for centre-cracked, pathed aluminum alloy thin sheets 7075-T76 are then presented. These show that adhesive layer stiffness had only a moderate effect differential contraction stresses had much less effect than predicted and neither variations in surface treatment of the aluminum alloy before bonding nor exposure of the patched sheet to warmmoist conditions had anyh substantial effect on crack rates. Bond durability wedge and peel tests did however hsow marked effects of alloy pretreatments. Explanations are advanced for the lack of effect of moisture and alloy pretreatment on the alloy-adhesive bonds of the patched sheets.