Comparison of measured and calculated interfacial strains at CFRP plate end

ABSTRACT

Small-scale steel beams reinforced with adhesively bonded carbon fiber reinforced polymer (CFRP) plates were subjected to four-point bending. Phase-stepping 3Ddigital speckle pattern interferometry (DSPI) was employed to measure the strain concentrations near the end of the CFRP plate, with a special focus on shear and normal strains. Furthermore, a refined finite element analyses (FEA) of the strengthened beam was carried out to predict these strains. Comparisons between measured and calculated strains have confirmed the strong variation of shear strain across the adhesive layer. The FEA has also shown the much higher normal strains present at the adhesive-steel (AS) interface than at the plate-adhesive (PA) interface. This difference has been suggested as the reason why debonding failure more commonly occurs at the AS interface rather than the PA interface.